PS

Heredity and Evolution

Important points :-
1) Heredity is the transfer of biological characters from one generation to another via genes.
2) The proteins are synthesized by DNA through RNA. This IS called as Central Dogma.
3) mRNA Is produced from one of the two strands of DNA. The sequence of nucleotides In mRNA Is complementary to the‘DNA strand used for synthesis. The only change is there is uracil in. RNA instead of thymine. in DNA. This process of RNA synthesis is called transcription.
4) mRNA formed In the nucleus comes in the cytoplasm and brings the coded message from DNA. The message contains the code for amino acids the code for each amino acid consists of three nucleotides. It Is called as triplet codon.
5) As per the message on mRNA the amino acids are supplied by tRNA which has anticodons having complementary sequence to the codons on mRNA. This called translation.
6) During the process of protein synthesis, the ribosome keeps on moving from one end of mRNA to other end by the distance of one triplet codon. This is called translocation.
7) Sometimes, any nucleotide of the gene changes its position that causes a minor change which is called as mutation.
8) Formation of new species due to changes in specific characters of several generations of living organisms as a response to natural selection, is called evolution. Evolution is the gradual change occurring in living organisms over a long duration.
9) Theory of evolution: First living material has been formed in ocean. In due course of time unicellular organism was formed. Gradually, changes occurred in them and from them larger and more complex organisms were formed. The whole process is very slow and gradual.
10) The evidences for the theory of evolution are: (i) Morphological evidences.(ii) Anatomical evidences (iii) Vestigial organs (iv) Paleontological evidences. (v) Connecting links (vi) Embryological evidences.
11 ) Carbon dating: Carbon consumption of animals and plants stops after death. C-14 being radioactive continues to decay but the amount of C-12 remains the same. Thus, the ratio. of C-14 to C-12 goes on reducing. From this ratio the age of fossils of plants and animals can be determined.
12) Darwin’s theory of natural selection: All the organisms reproduce prolifically. They compete with each other in a life-threatening manner. in this competition, those who are fit to survive, survive and others perish.
13) Some of the organisms, acquire some characters during their lifetime by the principle of use or disuse of organs. These characters are transferred from one generation to another generation. This is called as Lamarckism.
14) Formation of new species is the effect of evolution genetic variation, geographical and reproductive changes as well as geographical and reproductive isolation also contributes to the formation of new species. The formation of new species is called as speciation.
15) Humans have been evolved from the ape-like animals Today’s human being (Homo sapiens) is the result of evolution process which continued for the last about 7 crores of years.

Q.1(A)Complete the statements by choosing correct Options from bracket.
(Gene. Mutation, Translocation, Transcription Gradual development, Appendix)
*a.The causality behind the sudden changes was understood clue to –principle of Hugo de Vries.
*b.The proof for the fact that protein synthesis occurs through was given by George Beadle and Edward Tatum.
*c.Transfer of information from molecule of DNA to mRNA is called’es process.
*d.Evolution means —.
*e. Vestigial organ present in human body Is a proof of evolution.

Ans: (a)mutation (b)gene (c)transcription (d)gradual development (9) appendix

Q.1.(B) Answer the following questions.
*(i) Which component of the cellular nucleus of living organisms carries hereditary characters?

Ans: Genes.

*(ii) What do we call the process of transfer of physical and mental characters from parents to progeny?;

Ans: Heredity

*(iii) What is the function of appendix in our digestive system?
Ans: The appendix in human digestive system is a vestigial organ and it has no function.

*(iv) Are our Wisdom teeth really useful for chewing the food?
Ans: No, our wisdom teeth are not useful for Chewing the food. They are vestigial organs.

Q.2. Answer the following questions.

*i) Complete the following diagram
*(ii)Define heredity. Explain the mechanism of hereditary changes.
Ans: (1)The transfer of biological characters from one generation to another via genes is called heredity.
(2)The reason for sudden changes is ‘the mutations of genes.
(3) When male gametes and female gametes and female gametes combines, some combinations are same as parents where as parents where as some combinations are recombinations which are different from the parents. Due to these recombination, hereditary changes occur.

*(iii) How are the hereditary changes responsible for evolution?
Ans: If the hereditary changes are useful for survival of an organism, such organisms survive. Those which do not have such changes perish. The organisms survived reproduce and pass on these changes to next generation. Thus, an evolved organism comes into existence. This is how the hereditary changes are responsible for evolution.

*(iv) Which are the components of DNA molecule?
Ans: The DNA are made up of nucleotides. Each nucleotide consists of a phosphate, deoxyribose sugar and a nitrogen base. Nitrogen bases are of four types. They are (i) Adenine (ii) Guanine (iii) Cytosine and (iv)Thymine.

*(v) Why are many species of animals and birds _ getting extinct?
Ans: (1) Destruction of their habitats because of  urbanisation and industrialization.
(2) Pollution
(3) lmbaiances in the food chain
(4) Inability to survive in adverse conditions
(5) Deforestation
(6) Illegal hunting of wild animals.

Q. 3 (A) Read the following statements and justify in your own words with the help of examples.
*a. Human evolution began approximately 7 crore years ago.
Ans: (1 ) When dinosaurs got extinct about 7 crore years ago, at that time monkey like animals similar to modern. lemurs were evolved from some ancestors.
(2) These animals lost their tails about 4 crore years ago and Egyptopitheous were evolve.
(3) From these ape-Iike animals Dryopithecus Were evolved about 2.5 crore years ago.
(4) From these, animals of erect posture and using their hands for some work were evolved about 2 Crore years ago.
(5) The first human-Iike animals Ramapithecus were evolved about 1 crore years back.
(6) More intelligent and grown up in size’animals Austrelopithecus were evolved about 40 lakh years ago.
(7) The first skilled human walking with erect posture was evolved about 20 lakh years ago.
(8) Further about 50,000 years ago humans with their brain sufficiently developed, were evolved. Thus, it is clear that the human evolution began approximately 7 crore years ago.

*b. Geographical and reproductive isolation bf organisms gradually leads to speciation.
Ans: (1) Speciation means the formation of new and distinct species in the course of evolution.
(2) Geographical isolation may be due to rivers, mountains etc. They divide the population into more than one parts which are isolated from each other. These parts may evolve into different species due to evolution.
(3) If due to geographical isolation, a population is divided into two parts they are likely to become genetically different. If due to some reasons, these two parts together reproduce, a new species is likely to be created.

*c. Study of fossils’ Is an important aspect of study  of evolution.
Ans:(1) To know which organism is evolved from which organism, it is essential to know the order in which these two organisms existed.
(2) The study of fossils helps in .deciding the order in which various organisms existed. The layers in which the fossils are found indicate the period in which the different organisms were evolved.
(3) The carbon dating process helps In deciding the age of different fossils of different organisms.

*d. There are evidences of fetal (foetal) science among chordates.
Ans: (1) Fetal science Is the study of embryos.
(2) If we study the embryos of various chordates like fish, Salamander, tortoise, Chicken, pig, cow, rabbit and man in their earlier stages, we find that there is remarkable similarity among them.
(3) This is an evidence for them) be having a common ancestry.

0.3.(B) Answer the following questions.
*(i) Explain the meaning of genetic disorders and give names of some genetic disorders.
A: (1) Diseases or disorders occuring due to abnormalities in chromosomes and mutations in genes are called genetic disorders.
(2) Following are the names of some of the genetic disorders: (i) Down syndrome (ii) Turner syndrome (iii) Klinefelter syndrome (iv)Albinism (v) Sickle cell anaemia.

*(ii) Why did the huge animals like dinosaur become extinct?
A: Following are the possible reasons for the extinction of dinosaurs:(i) Crashing of a huge meteorite on earth (ii) They could not withstand’the eitreme changes in weather (iii) Eruptions of volcanoes (iv) Out of starvation (v) Certain fatal diseases.

*(iii) Explain with suitable examples importance of anatomical evidences in evolution.
Ans: (1) Though some animals are different In external appearance, some of their internal structures show resemblance. These are the anatomical evidences supporting the theory of evolution.
(2) Human hand, cat’s fore leg, patagium of bat and flipper of whale are different organs of different animals. They look different and have different functions. But if we study their bone structures and bony joints, we find similarity in them. They suggest that all these animals must have some common ancestry. The gradual change supports the evolution process.

*(iv) Define fossil Explain importance of fossils as proof of evolution.
Ans: (1) Large number of organisms got buried due to disasters like flood, earthquake, volcano eruption etc. Remnants and impressions of such organisms remain preserved underground. These are called as fossils.
(2) To know which organism is evolved from which organism, it is essential to know the ‘order in which these two organisms existed.
(3) The study of fossils helps In deciding the order in which various Organisms existed. The layers In which the fossils are found indicate the period in which the different organisms were evolved.
(4) The carbon dating process helps in deciding the age of different fossils of different organisms. Thus, fossils are important proofs of evolution.

*Q.4(A) Write short notes based upon information known to you.
(a) Lamarckism (b) Darwin 3 theory of natural selection (c) Embryology (d) Evolution (e) Connnecting link.
Ans: *(a) Lamarckism:- (1) Jean-Baptist. Lamarck. proposed that morphological changes occurring in living organisms are responsible for evolution.
(2) The reason behind those morphological changes is either activities done frequently by that organism or the [laziness showed by that organism in using a particular organ.
(3) For example, the frequent use of neck fer stretching and eating leaves of tall trees by giraffe has resulted into its neck becoming long in several generations.
(4) Ostrich and-emu do net use their wings very. often, so their wings have become weak.
(5) These are all acquired characters and Lamarck claimed that these acquired characters are transferred from one generation, to other This is called as theory of inheritance of acquired characters or Lamarckism
(6) Development or degeneration of organ according to its use was widely accepted but transfer of such characters to the next generation was rejected and Lamarck’s theory was disproved.

*(b)Darwin’s theory of natural selection -(1) The theory of natural selection is based on the principle survival of the fittest.
(2) All organisms reproduce in large numbers.
(3) They have to compete with each other for survival.
(4) In this competition, those who show the modifications which are essential for winning the competition, survive and others die.
(5) The selection of the organisms which are tit to live is done by nature.
(6) Such surviving organisms reproduce and the modifications useful for survival are passed on.
(7) Though this theory Was accepted by many, there are some objections raised also. They are (i) Natural selection is not the only factor responsible for evolution. (ii) There is no mention about the useful and useless modifications In the theory. (iii) There’ Is no explanation about the slow changes and abrupt changes.

*(c) Embryology :-(1) Embryology Is a branch of biology that studies the prenatal (before birth) development of gametes, fertilization and development of embryos and foetuses.
(2) Embryological evidences support evolution theory. The. study of embryos of various chordates like fish, Salamander, tortoise, chicken, pig, cow, rabbit and man in their earlier stages, reveals that there is remarkable similarity among them. It suggests the common ancestry for these animals.
(3) Embryology also deals with the congenital disorders that occur before the actual birth.
(4) Study of embryology is helpful in evolutionary developmental biology, mutations and stem cell research.

*(d) Evolution:- (1) Charles Darwin put forth the theory of evolution.
(2) Evolution is the gradual change occurring in living organisms over a long period.
(3) It is a very slow going continuous process.
(4) Evolution can else be explained as the formation of new species due to changes in specific characters of several generations of living organisms as a response to natural selection.
(5) The first living material (protoplasm) is assumed to be formed in the ocean.
(6) Gradually, unicellular organisms and then multicellular complex organisms were evolved from the. protoplasm.
(7) The changes took place due to mutations in genes. if the changes occurred due to mutations were helpful for the survival of the organism, these organisms survived. They transmitted these genes to the next generation.
(8) the organisms which did not have such changes essential for the survival, perished.
(9) Evolution is the progressive development of plants and animals from the ancestors having different Structural and functional organization.
(10) Due to evolution only, we find the tremendous variety in plants and animals today.
(11) Morphological, anatomical, paleontological, embryological evidences, connecting links and vestigial organs support the theory of evolution.

*(e) Connecting links:– (1) Some plants and animals show some morphological characters by which they can. be related to two different groups, hence they are said to be connecting links.
(2) They support the theory of evolution and suggest which-group must have been evolved from which group.
(3) For example, in Peripatus, some characters of Annelida like segmented body, thin cuticle, parapodia-like organs are seen. At the same time, it has some characters of Arthropoda. like tracheal: respiration, open circulatory system etc. i.e. Peripatus is a connecting I link between Annelida and Arthropoda and It suggests that Arthropods must have been evolved from Annelids.
(4) Another example is Duckbill platypus. It lays eggs like reptiles but have mammary glands and hair like mammals. Thus it is a Connecting link between reptiles and mammals and suggests that Mammals are evolved from Reptiles.
(5) Lung fish has many characters of fish but its respiration is with the lungs. So, it IS a connecting. link between Amphibians and Pisces.

Q.4.(B) Answer the following questions.
*(i) Define vestigial organs. Write names of some vestigial organs in human body and’write the name of those animals in whom same organs are functional.
Ans: (1) Degenerated or underdeveloped useless organs of organisms are called as vestigial organs.
(2) Following table shows the list of vestigial organs in human body and the names of animals In which these organs are functional. Also the functions In other animals are given in the table

(ii) Explain the process of formation of complex proteins.
Ans: (1) Information about protein synthesis is stored in the DNA. Accordingly, proteins are synthesis by DNA through RNA. This is called as central dogma.
(2) Only one of the two strands of DNA is used to produce mRNA. The sequence of nucleotides in mRNA is complementary to the DNA strand used. In place of thymine of DNA there is uracil in mRNA. This process of producing mRNA from DNA is called as transcription.
(3) The mRNA formed in nucleus comes id cytoplasm along with the coded message from the DNA.
(4) This message contains the code for each amino acid. The code consists of three nucleotides and is called as triplet codon. Each mRNA consists of thousands of triplet codons.
(5) As per the message on mRNA, amino acids are supplied by tRNA. For this purpose, tRNA has anticodon having complementary sequence to the codon mRNA. This is called as translation.
(6) The amino acids brought in by tRNA are bonded together by peptide bonds with the help of rRNA. During this process, the ribosome keeps on moving from one end of mRNA to the other end by the distance of one triplet codon. This is called as translocation.
(7) Such many chains come together to form complex proteins.

*(iii) Explain the theory of evolution and mention the proofs supporting it.
Ans: (1 ) Charles Darwin put forth the theory of evolution.
(2) Evolution is the gradual change occurring in living organisms ever a long period.
(3) It is a very slow going continuous process.
(4) Evolution can also be explained as the formation of new species due. to changes in specific characters of several generations of living} organisms as a response to natural selection.
(5) The first living material (protoplasm) is assumed to be formed in the Ocean.
(6) Gradually, unicellular organisms and then multicellular com plex organisms were evolved from the protoplasm.
(7) The changes took place, due to mutations In genes. If the changes occurred due to mutations were helpful for the survival of the organism, these organisms survived. They transmitted these genes to the next generation.
(8) The organisms which did not have such changes essential for the survival, perished.
(9) Evolution is the progressive development of plants and animals from the ancestors having different structural and functional organization.
(10) Due to evolution only, we find the tremendous variety in plants and animals today.
(11) Morphological, anatomical, paleontological, embryological evidences, connecting links and vestigial organs are the proofs supporting the theory of evolution.

*(iv) Write evolutionary history of modern man.
Ans: (1) When dinosaurs got extinct about 7 more years ago, at that time monkey like animals similar to modern lemurs were evolved from some ancestors.
(2)These animals of Africa lost their tails about 4 crore years ago, and Egyptopithecus were evolved.
(3) From these ape-like animals Dryopithecus were evolved about 2. 5 crore years ago.
(4) Later, their Lumbar bones got developed and from these, animals’of erect posture and using their ‘ hands for some work Were evolved about 2 Crore years ago.
(5) The first human like animal Ramapithecus was evolved about 1 crore years back.
(6) More intelligent and grown up in size animals Austrelopithecus were evolved about 401 lakh years ago.
(7) The first skilled human walking With erect posture was evolved about 20 lakh years ago.
(8) Further, about 50,000 years ago humans with their brain sufficiently developed, «were evolved. They could be considered as member of the class wise man (Homo sapiens).
(9) Neanderthal and Cro-Magnon can bet considered as wise men.
(10) About 10, 000 years ago} man started practicing agriculture, rearing cattle herds and establishing cities.
(11) Subsequently, cultural development took place. Art of writing was developed about 5000 years? ago and the history started.
(12) Modern sciences emerged about 400 years ago and industrial society was established about 200 years ago.

*(v) Sketch and explain the structure of DNA and various types of RNA.
Ans: DNA :-

(1) DNA is made up of two parallel strands.
(2) Each Strand is made up of many nucleotides.
(3) Each nucleotide Is made up of a deoxyribose sugar, phosphate and a nitrogen base.
(4)’The two strands are joined to each other by nitrogen bases of nucleotides.
(5) This structure is somewhat like a twisted ladder.
(6) There are four types of nitrogen bases: (i) Adenine (ii) Guanine ‘ (iii) Cytosine and (iv) Thymine.
(7) Adenines and guanines are called purines whereas cytosine and thymine are called pyrimidines.
(8)Adenine and Thymine are always joined to each other while Guanine and Cytosine are joined to each other.

RNA:-

(1)RNA Is made up of one strand.
(2)The strand is made up of many nucleotides.
(3)Each-nucleotide consists of ribose sugar, phosphate and a nitrogen base.
(4)The four types of nitrogen bases are (i) Guanine (ii) Cytosine (iii) Adenine (iv) Uracil.
(5)There are three types of RNA: (i) Ribosomal RNA (rRNA) They do proteins synthesis. (ii) Messenger RNA (mRNA) They carry the information of Protein synthesis from genes to ribosomes. (iii) Transfer RNA (tRNA)-They carry the amino acids to ribosomes as per the message received from mRNA.

*(Vi)Which are the different organs in body of organisms? Is each of the organs useful to organism?
Ans: (1) Following are some important organs in different organ systems of-humans:
Respiratory system (i) Lungs (ii) Trachea (iii)
Bronchi Digestive system (i) Mouth (ii) Oesophagus (iii) Abdomen (iv) Intestines (v) Liver (vi) Pancreas
Circulatory system (i) Heart (ii) Arteries (iii) Veins
Nervous system (i) Brain (ii) Spinal cord (iii) Nerves
Excretory system (i) Kidneys (ii) Ureters (iii) Urinary bladder
Reproductive system(In males)(i)Prostate glands (ii) Testes (iii) Penis
                                      (In females) (i) Ovary (ii) Uterus (Iii) Vagina
(2)All these organs are useful to humans. Only vestigial organs are not useful for the organisms

Life Processes in living organisms Part -1

Important points:
1) In living organisms, the respiration occurs at two levels: (i) at body level and (ii) at cellular level.
2) In cellular respiration, glucose is oxidised step by step in the mitochondria of cells.
3) If oxygen is involved In the respiration, it Is called as aerobic respiration and, if oxygen is not involved In the respiration, it is called anaerobic respiration.
4) In aerobic respiration, glucose is oxidised in three steps :
(i) Glycolysis Glucose molecule is oxidised and two molecules each of pyruvic acid, ATP, NADH₂ and water are formed. Molecules of pyruvic acid are converted into molecules of acetyI-coenzyme-A. Two molecules of NADH₂ and two molecules of CO₂  are released.

(ii) Tricarboxylic acid cycle  Acetyl part of AcetyI-coenzyme-A is completely oxidised in mitochondria and molecules of CO2 and NADH2, FADH₂ are derived.

(iii) Electron transfer chain reaction 3 molecules of ATP are obtained from each ‘molecule of NADH2 and 2 molecules of ATP are obtained from each molecule of FADH2 molecule. Beside ATP, water molecules are also formed. Electron transfer , chain reaction is operated in mitochondria.
5) In anaerobic respiration, glycolysis and fermentation are the two steps.
6) Digestion of proteins gives amino acids while digestion of lipids gives fatty acids.
7) There are two types of Cell division: (i) Mitpsis (ii) Meiosis.
8) Mitosis is carried out In four phases (i) Prophase (ii) Metaphase (iii)Anaphase (iv) Telophase.
9) Meiosis is carried out In two parts.
10) Mitosis occurs in somatic cells and stem cells while meiosis occurs in germ cells

*Q.1.(A) Fill In the blanks.
a.After complete oxidation of a glucose molecule, _______ number of ATP molecules are formed.

b.At the end of glycolysis,_________molecules are I obtained.

c.Genetic recombinatlon occurs in________phase Of prophase of meiosis-1

d. All chromosomes are arranged parallel to equatorial plane of pell in_____phase of mitosis. 

e.For formation of plasma membrane,_____ molecules are necessary.

f.Our muscle cells perform_____type of respiration during exercise.
Ans:(a)38 (b) pyruvic acid, ATP, NADH 2and water   (c)third          (d) Metaphase       (e) phospholipid      (f) anaerobic

Q.1(B) Fill In the blanks with suitable options.
(I)is called as our energy currency
(a)NADHZ          (b)FADH2          (c)ATP        (d)NADP

(ii)Krebs cycle takes place in_______ .
(a)lungs         (b)mitochondria         (c)nucleus of cell        (d)alveoli

(iii)During the anaerobic respiration in muscle cells______is produced.
(a)lactic acid         (b)alcohol           (c)citric acid        (4)butyric acid

(iv)We get______ Kcal of energy per gram of lipids.
(a)1 (b)3 (c)4 (d)9

(v)Meiosis occurs in _____ cells
(a)germ (b) somatic (c) stem (4) blood

Ans: (i) ATP (ii) mitochondria (iii) lactic acid (iv) 9  (v)germ

*Q.1. (C) Write definitions
(a)Nutrition
(b)Nutrients
(c)Proteins
(d)Cellular respiration
(e)Aerobic respiration
(f)Glycolysis
Ans: (a) Nutrition:- The process of providing or obtaining the food necessary for health and’growth is called nutrition.
(b) Nutrients:- substance that provides nourishment essential for the maintenance of life and for growth Is called nutrient.
(c) Proteins:- Nitrogenous organic compounds composed of one or more large. chains of amino acids which are an essential part of all living-organisms are Called proteins.
(d) Cellular respiration:- The process of obtaining energy by step by step oxidation of glucose In a Cell,is called cellular respiration.
(e)Aerobic respiration:- The process of respiration in which oxygen is involved Is called aerobic respiration.
(f)Glycolysis:- A process occurring in cytoplasm, in which a molecule of glucose is oxidised step by step and two molecules each of pyruvic acid, ATP, NADH₂ and water. are formed, is called glycolysis.

Q. 1. (D) Answer the following questions.
*(i) Which system Is in action for removal of waste materials produced In human body?
Ans: The excretory system is in action for removal of waste materials produced In human body.

*(ii) Why do the players consume some food stuff during the breaks of game?
Ans: While playing, players consume energy. To get new energy, they consume some food stuff which gives them instant energy.

*(iii) How many atoms of C, H and O are respectively present in a molecule of glucose?
Ans: In a molecule of glucose (C6 H12O6) there are 6 atoms of C 12 atoms of H and 6 atoms of O.

*(iv) Which types of chemical bends are present between all the atoms in a glucose molecule?
Ans: Covalent bonds are present between the atoms of glucose molecule.

*(v) Which type of cellular respiration performs Complete oxidation of glucose?
Ans: Aerobic respiration performs complete oxidation of glucose.

*(vi) Which cell organelle Is necessary for complete oxidation of glucose?
Ans: The organelle mitochondrion is necessary of complete oxidation of glucose.

*(vii) Why is inflammation / ulceration caused in mouth?
Ans: Deficiency of vitamins B₁ (Thiamine) and B₂ (Riboflavin) Is one of the causes of inflammation / ulceration in mouth.

(viii)Why do some persons experience difficulty in night vision since their childhood or adolescence?
Ans: The disorder is called as night blindness and it i Caused due to the deficiency of vitamin A.

*(ix) What happens to the cells of injured tissue?
Ans: The injured cells die and the other,cells of the tissue divide and the injured tissue is cured.

*(x)Whether new cells are formed during healing of wound?
Ans:The new cells are formed by the cell division.

*(xi) Do the plants get Injured when we pluck the flowers? How are those wounds healed? 

Ans: Yes,the plants get injured when we pluck the flowers. The wounds are healed by generation of new cells by cell division.

*(xii) What do you mean by coenzymes?
Ans: Coenzymes are non-proteins which are necessary for the functioning of enzymes.

*(xiii) What do you mean by diploid (2n) cell?
Ans: A diploid cell is a cell having two sets of chromosomes.

*(xiv) What do you mean by haploid (n) cell?
Ans: A haploid cell is a cell having one Set of chrombsomes.

*(xv) What do you mean by homologous chromosomes?
Ans: Homologous Chromosomes are a pair of chromosomes made up of one from father and one from mother haying same genes at same places.

*(xvi) Whether the gametes are diploid or haploid? Why?
Ans: (1) Gametes are haploid.
(2) They are haploid because they are formed by the meiotic division. Two haploid gametes fuse and give diploid zygote.

*(xvii) How are the haploid cells formed?
Ans: Haploid cells are formed from diploid .ceIIs by the process of meiotic division.

*(xviii) What is the importance of haploid cells?
Ans: They are capable of reproduction.On fusion, the give diploid zygote which grows into new individual.

*Q.2. (A)-Explain the following statements.
a. After complete oxidation of a glucose molecule, 38 number of ATP molecules are formed.
Ans: Oxidation of glucose molecule takes place In three stages: (i) Glycolysis (ii) Krebs cycIe and (iii) EIectron transfer chain reaction. After all the three stages are completed, the Oxidation of glucose is complete. The final products of all these three processes are CO_2, H₂O and energy in the form of ATP moIecuIes. The complete oxidation of one molecule of glucose gives 38 molecules of ATP.

b. At the end of glycolysis, pyruvic acid, ATP, NADH₂ and Water molecules are obtained.
Ans: Glycolysis IS the first stage of cellular respiration. It takes place in cytoplasm. A molecule of glucose is partially oxidised in this stage. The products are pyruvic acid, ATP(Adenosine triphosphate), NADH₂(Nicotinamide adenine) and water.

c. Genetic recombination occurs in the third phase of prophase of meiosis-1.
Ans: In meiosis-1,recombination/crossing over occurs . between homologous chromosomes and thereafter those homologous chromosomes are divided into two groups and thus two haploid cells are formed. All these processes take place In 5 stages. Out of these five stages genetic recombination occurs in the third stage called Pachytene. Here, the genetic information Is exchanged between two homologous chromosomes.

d. All chromosomes are arranged parallel to equatorial plane of cell in metaphase phase of mitosis.
Ans: In the metaphase, nuclear membrane disappears. The condensation of chromosomes is complete and they are clearly visible with their sister chromatids. All the chromosomes are arranged parallel to the equatorial plane i.e. the central plane Flexible protein fibres are formed between the centromere of each chromosome and the centrioles which are on the either side of the equatorial plane. The sister chromatids are ready for splitting into two halves at the centromere.

e. For formation of plasma membrane phospholipid molecules are necessary.
Ans: The plasma membrane is a bilayer of phospholipids and proteins embedded in it. So, phospholipids are the  major part of the structure of plasma membrane (cell membrane). So, for formation of plasma membrane, phospholipids are necessary.

f. Our muscle cells perform anaerobic type of respiration during exercise.
Ans: During exercise, certain muscles need more energy than the other muscles. In such muscles, anaerobic. respiration takes piece The energy is generated without the involvement of oxygen and muscles get extra energy needed In this process, glucose is partly oxidised and lactic acid is produced.

Q.2.(B) Distinguish between:
a. Glycolysis and TCA cycle.
Ans:

b.Mitosis and meiosis
Ans:

c. Aerobic rapiration and anaerobic.
Ans:

*Q.2(C) Give scientific reasons:
a.Oxygen is necessary for Complete oxidation of glucose.
Ans: (1) Cellular respiration in humans is an aerobic respiration.
(2) Aerobic respiration takes place in the presence of oxygen. Therefore, oxygen is necessary for complete oxidation of glucose.

b. Fibres are one of the important nutrients.
Ans: (1) Most of the fibres are not digested by Us. So,the food containing fibres gives us limited calories.
(2) Fibres help in the digestion Of other nutrients.
(3) As the fibres are not digested, they form a roughage for the faeces and help In egestion. Therefore, fibres are one of the important nutrients.

C.Cell division is one of the important properties of cells and organisms.
Ans: (1) For the growth of organisms, number of cells, need to be increased.
(2) Dead or injured cells need to be replaced for the maintenance of the body.
(3) For healing wounds, new cells are required.
(4) For reproduction of organisms also, generation pf new cells is essential.
(5) The only way to produce new cells is the cell division. Therefore, cell division Is one of the important properties of cells and organisms.

d.Sometimes,higher plants and animals too perform anaerobic respiration.
Ans: (1)When energy is required but availability of oxygen is not there then, anaerobic respiration needs to be done.
(2) During seed germination under the surface of the ground the availability of oxygen is Very low. So, in such case plants do anaerobic respiration
(3) During exercise or vigorous activities, some specific muscles need extra energy. In such case no extra oxygen is available, so the muscles perform anaerobic respiration. Therefore, sometimes, higher plants and animals too perform anaerobic respiration.

e.Krebs cycle Is also known as citric acid cycle.
Ans: When AcetyI-Coenzyme-A enters the Krebs cycle, it combines with four-carbon acid,(oxaloacetio acid) and forms a six-carbon acid called citric acid as the intermediate products. Therefore, Krebs cycle is also known as citric acid cycle.

Q. 2(D)Answer the following questions.
*i) How are the food stuffs and their nutrient contents useful for our body?
Ans:(1)Food stuffs contain the nutrients like carbohydrates, proteins, fats, vitamins, minerals and water.
(2)Carbohydrates and fats provide us the required energy.
(3)Proteins are necessary for the growth and maintenance of the body.
(4)Vitamins and minerals are required for immunity system and metabolism.
(5) Water Is a very important and major constituent of our body.

*(ii)What is the importance of balanced diet for body?
Ans: (1) Various nutrients are required by the body for growth, maintenance, energy production, fighting the diseases and performing metabolic activities.
(2)A balanced diet contains all these nutrients namely carbohydrates, proteins, fats, vitamins and minerals In proper proportion Therefore, the balanced diet is important fer the growth and Well being of the body.

*(iii) What is the importance of digestive juices in digestive system?
Ans: (1) The dietary nutrients like carbohydrates, Proteins and fats cannot be absorbed directly into our blood.
(2) The digestive juices convert them into soluble substances having smaller molecules.
(3) Carbohydrates are converted into glucose, proteins are converted into amino acids and fats are converted into fatty acids. These can be absorbed into our blood. Thus, the digestive juices are important In digestive system.

*(iv) What Is the role of circulatory system in energy production?
Ans:(1)The production of energy takes place in every cell (except RBCs).
(2)For energy production, glucose fatty acids and oxygen are necessary.
(3)The circulatory, system distributes them to each and every cell and enables the cells to do energy production.

*(v)In terms of chemistry what happens actually when a molecule is oxidised?
Ans: When a molecule is oxidised, either oxygen is added to the molecule, or hydrogen is given by, the molecule or electron/s are lost by the molecule.

*(vi)Why do we experience dryness in mouth sometimes?
Ans:(1)Mouth is kept wet by the secretion of saliva.
(2) If the intake of water is less than the required amount, then the secretion of saliva is less and we experience the dryness in mouth.

*(vii)Why is oral rehydration solution (Salt-Sugar-water) frequently given to persons experiencing loose motions.
Ans:(1)Lot of water and electrolytes are lost through loose motions.
(2) It IS necessary to maintain the proper level of water and electrolytes in our body for proper functioning.
(3) Also, the instant energy is required by the 3 patient which he Can get from sugar. So, oral rehydration solution is given to persons experiencing loose motions.

*(viii) Why do we sweat during summer and heavy exercise?
Ans:(1)The rate of sweating is directIy related to the body temperature.
(2)In summer or during heavy exercise, our body temperature increases and we sweat more. It maintains the normal temperature of our body.

*(viii) Why do we sweat during summer and heavy exercise?
Ans:(1)The rate of sweating is directIy related to the body temperature.
(2)In summer or during heavy exercise, our body temperature increases and we sweat more. It maintains the normal temperature of our body.

*(ix)How does the growth of any living organism occur? Does the number of cells in their body increase? If yes, how?
Ans:(1)The growth of any living organism occurs by the increase in the number of cells In its body.
(2) The number of cells Increases by the cell division.

*(x)How Is the new individual of a species formed from existing one of same species?
Ans:(1)The new individual IS formed either by asexual reproduction or by asexual reproduction.
(2)In both the cases the cells multiply by the process of cell division and new individual IS formed.

Q.3(A)Answer the following questions.
*(i)how energy is formed from oxidation of carbohydrates, fats and proteins? Correct the diagram given below.

*(ii)Which different functions are performed by muscles in body?
Ans:(1)To bring about movement of organs and involuntary movements.
(2)To maintain posture and body position.
(3)Movement of food and waste through gastrointestinal track.
(4) Constriction and dilation of pupils.
(5) Movement of diaphragm which enables the breathing.
(6) Pumping of blood by heart.
(7) Regulation of body temperature.

*(iii) What is respiration? How does it occur?
Ans:(1)Respiration Is a process by Which we obtain energy from the food we eat and oxygen we breath in.
(2)It Occurs at two levels. (a) At body level and (b) At cellular level.
(3) The respiration at body level Includes breathing In air,exchange of oxygen in breathed air and Carbon dioxide from the deoxygenated blood.
(4)This exchange takes place in alveoli in the lungs and carbon dioxide is breathed out along with water vapour.
(5)At cellular level, the respiration takes place in mitochondria.
(6)Glucose obtained by the digestion of dietary carbohydrates is step by Step oxidised and energy is released. In the process carbon dioxide and water are also produced.

*(iv) Read the following passage and answer the questions that follow.
Somatic cells and stem cells divide by mitosis. Mitosis is completed through two main steps. Those two steps are karyokinesis (nuclear division) and cytokinesia (cytoplasmic division). Karyokinesis is completed through four steps.

a. Name the four steps of karyokinesis in Proper order.
Ans: Prophase, Metaphase, Anaphase and Telophase.

b.What are somatic cells?
Ans:Any cell of a living organism except the reproductive cells (germ cells) are called the somatic cells.

c)In which step do the centromeres of chromosomes split and sister chromatids 3 separate.
Ans:The centromeres of chromosomes split and sister chromatids separate in anaphase.

0.4. Answer in detail.
*a. Explain the glycolysis in detail.
Ans:(1) Glycoiysis is the first stage of aerobic respiration taking place in the cell.
(2)It takes pIace in the cytoplasm.
(3) In this process, a molecule of glucose is oxidised step by step and two molecules of each pyruvic acid, NADH_2, ATP,  and water are formed.
(4) Molecules of pyruvic acid formed are converted into molecules of Acetyl-coenzyme-A In this process, two molecules of NADH₂ and two molecules of CO₂ are released.

*b. With the help of suitable diagrams, explain the mitosis In detail.
Ans: 1) Cell division of somatic cells and Stem cells occurs by mitosis.
(2)Mitosisc occursih two steps(i) karyokihesis and ii)Cytokinesis (3) Karyokinesis is complated in four stages :-

(ii) Metaphase:- In this phase, nuclear membrane completely disappears. Chromosomes complete their condensation and become clearly visible along with their Sister chromatids. All chromosomes are arranged parallel to equatorial plane (central plane) of the cell. Special type of flexible protein fibres (spindle fibres) are formed between centromere of each chromosome and both centrioies. 

(iii) Anaphase:- In this phase, centromeres split and thereby sister chromatids of each chromosome separate and they are pulled apart in opposite direction with the help of spindle fibres. Separated sister chromatids are called as daughter chromosomes. In this way, each set of chromosomes reach at two opposite poles of the cell.

(iv) Telophase:- The chromosomes which have reached ,at opposite poles of the cell now start to decondense due to which they again become thread like thin and invisible. Nuclear membrane is formed around each set of chromosomes reached at poles. Thus, two daughter nuclei are formed in a Cell. Nucleous also appears in each dauthter nucleus spindle fibres disappear.
(4) After karyokinesis Is complete, cytokinesis begins. A notch Is formed at the equatorial plane of the cell which deepens gradually and thereby two new cells are formed. In case of plants, instead of a notch a cell plate Is formed in the middle of the cell.

*.c With the help of suitable diagrams, explain the five stages of prophase-i of meiosis.
Ans:Following are the five stages of prophase-l of meiosis:-
(1) Leptotene:- in this stage, each chromosome becomes visible with two sister chromatids.
(2) Zygotene:- in this stage, homologous chromosomes begin to pair.
(3) Pachytene:- in this stage, the paired chromosomes shorten and thicken, the two chromatids of each separate and exchange of segments between chromatids occur.
(4)Diplotene:- In this stage, the paired chromosomes begin to separate into two pairs of chromatids.
(5) Diakinesis:- In this stage, separation of homologous chromosomes and crossing over is completed.

*d. How all the life processes contribute to the growth and development Of the body?
Ans:(1)Nutrition provides us all the nutrients required for energy generation and growth. After digestion, these nutrients are converted into soluble substances Which can be absorbed by the blood.
(2)Respiration generates the energy from glucose and fatty acids. This energy is required by us for all the activities we do.
(3) Blood circulation ensures that all the glucose, fatty acids, amino acids, Oxygen, various hormones etc. are distributed to each cell of the body.
(4)Proteins are synthesised from amino acids by the cells. These proteins are required for the growth.
(5)The coordination end control function is done by the nervous system central nervous system controls all the Voluntary and involuntary actidns in a coordinated manner. Various endocrine glands secrete various. hormones which have a chemical control on many activities. Thus, all the processes contribute to the growth and development of the body.

*.e Explain the Krebs cycle with reaction.
Ans:(1)It is also called as tricarboxylic acid cycle (TCA Cycle) or citric acid cycle.
(2) Both molecules of acetyl-coenzyme-A produced in glycolysis, enter the mitochondria. Cyclic chain of reactions called as tricarboxylicl acid cycle is operated on it in the mitochondria Acetyl part Of acetyl-CoA is completely oxidized through this cyclical process and molecules of CO₂,  H₂O, NADH₂ and FADH₂ are derived.

*f.How are the various processes occurring in human body controlled? In how many ways?
Ans:(1)There are two systems which control various processes in human body They are
(A)Nervous control and
(B)Chemical control.
(A)Nervous control:-(1)Neurons are the functional and structural units of nervous system.
(2) Nervous system comprises of Central nervous system peripheral nervous system and autonomous nervous system.
(3)Central nervous system consists of brain and spinal cords central nervous system controls voluntary movements, involuntary movements, body balance, thinking, concentration, reflex actions etc.
(4)Peripheral nervous system does the function of carrying impulses.
(5) Autonomous nervous system consists of the nerves of involuntary organs like heart, lungs, stomach etc.

(B)Chemical control:- (1)The chemical control and coordination in humans is brought about by various hormones. Hormones are secreted by endocrine glands. These glands are ductless glands. As soon as hormones are produced in these glands, they are directly released into the blood Thus, though-the endocrine glands are present at specific locations,their secretions reach all. the parts of the body via blood.
(2)The action of hormones is very, slow but it is long lasting.
(3)It is Very important that hormones are secreted in the required quantities only. There is a special mechanism which controls the quantity and timing of hormone secretion. e.g. Whenever the level of glucose in blood increases, certain cells in pancreas get stimulated and secrete more insulin. Insulin then controls the blood-glucose level.
(4) Following are some hormones and their functions.

Life Processes in Living Organisms Part – 2

Important points:
1)There are two methods of reproduction(i)Asexual reproduction and (ii)Sexual reproduction
2)In Asexual reproduction, there is no involvement of gametes and only one parent is involved. Generic recombination is absent in this method but the process is comparatively fast.
3)In sexual reproduction, male gametes and female gametes are involved. They fuse together to form a zygote which further develops into an embryo In this method, two parents are involved, one male and one female.
4)Binary fission, multiple fission, budding are some of the types of asexual reproduction In unicellular organisms.
5)Fragmentation regeneration, budding, vegetative propagation, spore formation are some of the types of asexual reproduction in multicellular organisms.
6)In sexual reproduction, two main processes occur
(i) Gamete formation and (ii) Fertilization
7)Haploid gametes are formed by the process of meiosis Such male gamete and female gamete fuse together to give a diploid zygote. This is celled as fertilization. The zygote divides mitotically te form embryo which finally develops into a new young one.
8)In sexual reproduction of plants, flower is the main part. It has male organs (Androecium) and female organs(Gynoecium).
9)Androecium consists of anther and filament while gynoecium consists of stigma, style and ovary.
10)Pollen grains are produced in anther.
11)The process of transfer of pollen grains to the stigma is called pollination. When pollen grains from the another of a flower are transferred to the stigma of same flower or the other flower of the same plant, it is called as self pollination. When pollen grains from the anther of a flower are transferred to the stigma of a flower a other plant of same species, it is called as cross-pollination.
12)Prostateglands, Cowper’s glands, seminal vesicles, vas deferens, epididymis, testes, penis are important reproductive organs of human males.
13)Ovary, oviduct, uterus and vagina are important reproductive organs of human females.
14)During copulation, human male releases sperms through his penis into the vagina of female. Sperms travel to the oviduct and fertilize the ovum present in the oviduct.
15) After fertilization, a zygote is formed which undergoes repeated mitotic divisions and embryo is formed. It is implanted into uterus. The embryonic development is completed in approximate 9 months and the baby is born.
16)Female has both X type sex chromosomes while male has one X type and one Y type sex chromosome. During fertilization, if X chromosome of female combines with x chromosome of male, girl child is born. X chromosome of female combines with Y chromosome of male, a boy child is born.
17)If oocyte is not fertilized, then endometrium starts degenerating. Tissues of degenerated endometrium, unfertilized ovum along with blood are thrown out of vagina. This bleeding continues for about 5 days. This is called menstruation.
18)Some couples cannot have child due to various problems. The couples who have problems like less sperm count, obstacles In oviduct can use In Vitro Fertilization (IVF) technology In this technology, the fertilization is brought about In a test-tube and the embryo Is implanted In the uterus of the Woman.
19)Some women have problems in implantation of embryo in uterus. In this case, oocyte is collected from Ovary and it is fertilized in a test-tube using the sperms collected from his husband and the embryo thus formed is implanted in the uterus of some other woman (surrogate mother). This technique is called as surrogacy.
20)if there is a problem inthe sperm production in male, then the oocyte of the woman can be fertilized using semen of some other person from the semen bank by IVF technology and the embryo Is implanted in the uterus of the same woman.
21)Monozygotic twins are formed from single embryo they are identical and of same gender.
22)Dizygotic twins are formed when two oocytes are released from the ovary of a woman and both of them get fertilized by separate sperms. These are genetically different and their genders may be same or different.
23)One must take care of one’s reproductive health and keep away from sexually transmitted diseases.
24)Family planning is the only way to solve the problems arising out of population explosion.

Exercise

Q.1.(A)Fill In the blanks.
*a. In humans, sperm production occurs in the organ_____.
*b.In humans,_______ehromosorne Is responsible for maleness.
*c.In male and female reproductive system of human,______gland Is same.
*d.Implantation of embryo occurs in________.
*e.______type of reproduction occurs Without fusion of gametes.
*f.Body breaks up into several fragments and each fragment starts to live as a new individual. This is _________type of reproduction.

*g.Pollen grains are formed by_______ division in locules of anthers.
Ans (a)testes (b)Y-chromosome (c)bulbo-urethral gland (Called Bartholin’s gland In females) (d)uterus (e)asexual (f)fragmentation (g) meiotic

Q 1.(B)Select the proper options and rewrite the statements
(i)In adverse conditions, amoeba reproduces by the method of_____.
(a)Simple binary fission (b)transverse binary fission
(C)longitudinal binary fission (d)multiple fission.

(ii)_______reproduces by the method of budding.
(a)Paramecium (b)Yeast (c)Euglena (d)Bryophyllum

(iii)The minimum ages of boys and girls for marriage as fixed by the law are______and_____ years respectively.
(a)18 and 21 (b)20 and 18 (c)21 and 18 (d)18 and 15

(iv) Which of the following is not an organ related to the reproductive system of humans?
(a)Prostate gland (b)Salivary gland (c)Oviduct (d)Epididymis

(V)In______technique, the fertilization is brought about inthetest tube.
(a)lVF (b)Surrogacy (c)In (a) and (b) both (d)None of the above

Ans:(i)multiple fission     (ii)Yeast     (iii)21 and 18     (iv)Salivary gland      (v)In (a) and (b) both

*Q.1.(C)Give the names.
a.Hormones related with male reproductive system.
Ans:(1)Testosterone (2)Follicle-stimulating hormone(FSH) (3)Luteinizing hormone

b.Hormones secreted by ovary of female reproductive system.
Ans: (1)Oestrogen (2)Progesterone

c.Types of twins.
Ans:(1)Monozygotic twins (2)Dizygotic twins

d.Any two sexual diseases
Ans:(1)Syphiiis (2) Gonorrhea

e.Methods of family planning.
Ans:(1)Taking contraceptive pills (for women)
(2)Tubal ligation (for women)
(3)Using condoms (for men)
(4)Vasectomy (for men)

Q.1.(D)Answer the following questions.
*(I)Which life processes are essential for production of energy required by body?
Ans:(1)Respiration (2)Nutrition

*(ii)What is the role of chromosomes in cell division?
Ans: The role of chromosomes Is to distribute the genetic material (DNA) equally between the daughter cells.

*(iii)What do we mean by maintenance of species?
Ans:The coexistence of all the species, conserving the species diversity and preventing them from being extinct is the maintenance of species.

*(iv)Who determines Whether the two organisms of a species will be exactly similar or not?
Ans: Genes determine whether the two organisms of a species will be exactly similar or hot. Also, the type of reproduction determines whether the next generation will be exactly similar or not. In asexual reproduction, the new individuals are exactly similar where as in sexuaI reproduction, variation Is observed.

*(v)What would have been happened if the male and female gametes had been diploid?
Ans:if the male and female gametes were diploid, after their fusion a zygote would be formed containing double the number of chromosomes than the normal one Thus, the new organism would be abnormal.

*(vi)What would have happened if any of the cells in nature had not been divided by meiosis?
Ans: if there were no division by meiosis then the haploid gamete formation would not be there and there would be no sexual reproduction.

*(vii)Which hormones are responsible for changes in human body occurring during onset of sexual maturity?
Ans: Oestrogen In females and testosterone In males are responsible for changes In human body occurring during onset of sexual maturity.

*(viii)Which hormone is released from pituitary gland of mother once the fetal development is completed ?
Ans:The hormone oxytocin is released from pituitary gland which helps in contraction of uterus during

Q.2.(A)Answer the following questions.
*(i)Which are the main types of cell division? What are the differences?
Ans:(1)Two main types of ceII-division are (i)ceII-division by mitosis and (ii) cell -division by meiosis.
(2)Mitosis takes place in somatic cells and stem cells where as meiosis takes place in germ cells.
(3)Mitotic division gives two diploid daughter cells where as meiotic division gives four haploid daughter cells.

*(ii)Is the new organism genetically exactly similar to earlier one that has produced it?
Ans:(1)In case of asexual reproduction, the new organism is genetically exactly similar unless there is any mutation in genes.
(2)In case of sexual reproduction, the new organism is genetically different due to the recombination.

*(iii)What is the relationship between the cell division and formation of new Organism of same species by earlier existing organism?
Ans:In any type of reproduction, the genetic material has to be transferred to the cells Of next generation. Due reproduction zygote undergoes repeated cell divisions and develops into an embryo which produces new organism.

*(iv)Why has the Government of India enacted the law to fix the minimum age of marriage as 18 in girls and 21 in boys?
Ans:(1)At the age of 21 years in boys and 18 years in girls, they become sexually matured.
(2)Their sexual organs become capable of reproducing.
(3)They become mentally and physically capable for giving birth to the children and grow them properly Therefore, the Government of India has enacted the law to fix the minimum age of marriage as 18 in girls and 21 in boys.

*(v)Complete the following chart.

*(vi)Explain the concept of IVF.
Ans:(1)NF means In Vitro Fertilization.
(2)This technique is used on childless couples who have problems like less sperm count, obstacles in oviduct etc.
(3)In this technique, fertilization is brought about in the test-tube and the embryo formed iS implanted in uterus of woman at appropriate time.

*(vii)Which precautions will you follow to maintain the reproductive health?
Ans: Following precautions need to be taken to maintain reproductive health.
(1)In females, specially during the menstruation, the cleanliness of private organs(genitals) must be maintained.
(2)Males also are required to maintain the cleanliness of their genitals.
(3)Unprotected sex must be avoided by using condoms.
(4)One must keep away from the sexual diseases and in case of occurrence immediate treatment must be taken from expert doctors.

*Q.3.(A)Complete the paragraph With the help of Words given in the bracket.
(Luteinizing hormone, endometrium of uterus, follicle stimulating hormone, estrogen, progesterone, corpus luteum)
Growth of follicles present In the ovary occurs under the effect of______. This follicle secretes estrogen_____grows/ regenerates under the effect of estrogen. Under the died of______, fully grown up follicle bursts, ovulation occurs and_____is formed from remaining part Of follicle. It secretes_____ Under the effect of this hormone glands of________are activated and it becomes ready for implantation.
Ans:Growth of follicles present in the ovary occurs under the effect of follicle stimulating hormone. This follicle secretes estrogen. Endometrium of uterus grows regenerates under the effect of estrogen Under the effect of luteinizing hormone fully grown up follicle bursts, Ovulation occurs and coreus luteum is formed from remaining part of follicle. It secretes progesterone under the effect of this hormone, glands of endometrium are activated and it becomes ready for implantation.

Q.3.(B)Sketch the labelled diagrams
a.Human male raproductive system.

b.Human female reproductive system.

c.Flower with its sexual reproductive organs.

d.Menstrual cycle.

Q.3.(C) Answer the following questions.
*a.Explain with examples types of asexual reproduction In unicellular organisms.
Ans:The types of asexual reproduction in unicellular organisms are (i) Binary fission (ii) Multiple fission and (iii) Budding.
(i) Binary fission:(1)in this method, the living cell divides into two equal or nearly equal parts which have potential to grow to the size of the original one.
(2)If the plane of cytoplasmic division is any plane then it IS called as simple binary fission. e.g. Amoeba.
(3)If the plane of division is perpendicular to the long axis then it is called as transverse binary fission. e. g. Paramecium.
(4)If the plane of division is parallel to the long axis then it is called as longitudinal binary fission. e. g. Euglena.
(ii) Multiple fission: (1)During unfavourable conditions, the amoeba withdraws its pseudopodia and becomes almost round.
(2)It secrets a hard covering called cyst,
(3)Inside the cyst, its nucleus divides into many nuclei by repeated division followed by cytoplasmic division. As a result many daughter cells are formed.
(4)In favourable conditions, the cyst bursts open and amoeba are released.
(iii)Budding: (1)In this mode a small growth Is formed on the parental cell.
(2)The nucleus of the parental cell divides and one daughter nucleus migrates into the bud.
(3)The bud Increases in size separates and grows further e.g. Reproduction in yeast is by budding.

*b.What is menstrual cycle? Describe it in brief.
Ans:(1)The repetitive changes occurring in female reproductive system are called menstrual cycle.
(2)This cycle is of about 28-30 days.
(3)One of the several follicles in ovary starts to develop along with the oocyte present in it, under the effect of follicle stimulating hormone.
(4) This follicle secretes estrogen.
(5)Endomentrium of the uterus starts to develop (during the first cycle)or regenerate (during subsequent cycle) under the effect of estrogen.
(6)Developing follicle completes its development and bursts under the effect of luteinizing hormones and releases an oocyte. This is called ovulation.
(7)Remaining tissue of the burst follicle forms the corpus luteum.
(8)Corpus luteum starts to secrete progensterone. Endomentrial glands secrete their sectrtion under the effect of progensterone. Such endometrium is ready for implantation of enbryo.
(9)If oocyte is not fertilized within 24 hours, corpus luteum becomes inactive and transforms into corpus albicans. Due to this secretion of estrogen and progesterone stops and endometrium starts degenerating.
(10)Tissues of degenerating endometrium and unfertilized ovum are descarded out through vagina along wit bleeding. This is called mestruation. It lasts for about 5 days.

*c.In case of sexual reproduction, new born shows similarities about characters. Explain this statement with suitable examples.
Ans.(1)The genetic material is contributed by both parents to the young one.
(2)The combination of genes decides a particular character.
(3)If the combination of genes of a particular character in the young one is similar to that in one of the parents, then that character of young one is Similar to that parent.
(4)For example, consider a character of height. Let T be the dominant gene for height and t be recessive gene for the same. Let the genotype of male parent be Tt and that of female parent be it.
(5)in such situation, the male parent would be tall and the female parent would be short.
(6)If the combination of genes contributed by parents is T t in case of the young one, he will be tall like his father and if the combination is tt he will be short like his mother. T his is how the similarities in characters are shown by the you ng ones.

*d.Gender of child is determined by the male partner of couple. Explain with reasons whether this statement is true or false.
Ans:(1)The given statement Is true.
(2)In male partner two dissimilar sex chromosomes ere present ‘X’ and ‘Y’.
(3)In female partner, two ‘X’ sex chromosomes are present.
(4)Both the partners contribute one sex chromosome each during fertilization.
(5)As female partner has both ‘X’ chromosomes, she will contribute ‘X’ chromosome only.
(6)if male partner contributes ‘X’ chromosome, the combination will be ‘XX’ which pertains to a daughter. If male partner contributes ‘Y’ chromosome, the combination Will be ‘XY’ which pertains to a son. Thus, the gender of the child is determined by the male partner.

*e. Modern techniques like surrogate mother, sperm bank and IVF technique will help the human beings Justify this statement?
Ans:(1)Human beings are desirous of giving birth to children for various reasons.
(2)sometimes, due to following reasons, the conceiving is not possible (i)Men having less sperm count or having problem in sperm production. (ii)Obstacles in women’s oviduct. (iii)Inability of women for implantation of embryo on uterus.
(3)In such cases, surrogate mother, sperms bank and IVF technique can be solutions to the problem.
(4)If sperm count in men is less or there is some obstacle in women’s oviduct, IVF technique is used. Here, the fertilization is carried out in a test tube.
(5)If there is problem in the production of sperms, sperms from sperm bank can be used for fertilization.
(6)If a woman is unable to impact embryo in her uterus, the help of surrogate mother can be taken. Due to this, it has been possible to have child in spite of various problems. Thus, all these techniques help the human being.

*f. Complete the following chart

*Q.3(D)Complete the following chart

Q.4(A)Answer the following quations.
*(i)Explain asexual reproduction in plants.
Ans:Following are the different methods of asexual reproduction in plants:
(a)Fragmentation:-(1)This type of reproduction is seen in algae.(Algae is included in plant kingdom in two-kingdom classification)
(2)Whenever there is planty of water and nutrients available to spirogyara, its filaments grow fast and break up into many small fragments. Each fragment starts to live independently and grows as a new individual.
(b)Vegetative propagation:-(1)When new plants are produced from the vegetative parts (roots, stems, leaves and buds), it IS said to be vegetative propagation.
(2)For example, new plants of potato develop from eyes on potato which itself is a stem.
(3)Bryophyllum reproduces from the buds on the leaf margin.
(4)The roots of sweet potato give rise to new plants.
(c)Spore formation:-(1)The plants like ferns, reproduce by spores.
(2)They produce spares in sporangia which are at the back side of their leaves.
(3)As these are non-flowering plants, they do not have seeds and spores are their reproductive units.

*(ii)Explain sexual reproduction In plants.
Ans:(1)The flower is the functional unit In a plant’s sexual reproduction.
(2)Carpel consisting of stigma, style and ovary is the female reproductive part of a flower.
(3)Stamen consisting of anther and filament is the male reproductive part of a flower.
(4)In the process of pollination, the pollen grains from anther are transferred to the stigma.
(5)In self-pollination, pollen grains of a flower are transferred to the stigma of same flower or to the stigma of a flower of the same plant.
(6)In cross pollination, pollen grains are transferred to the stigma of a flower of another plant of the same species.
(7)After pollination, pollen grain germinates. The pollen tube grows out from it and travels through the Style to the each ovary.
(8)Each pollen tube contain two male gametes and releases them neat the egg. One male gemetes fuses with the egg cell to form zygote and the second male gamete fuses with two polar nuclei in the embryo sac to form endosperm. This is called as double fertilization.
(9)The zygote develops into embryo and the endosperm serves as nutritive tissue for the growing embryo. This embryo grows into a new Plant.
(10)The zygote divides several times to form embryo within the ovule. The ovule develops into a seed and ovary develops into the fruit.

(iii) Observe thefollowingfigure and answer the questions that follow.
Ans: a.Identify and name the numbered parts.
Ans:(1)seminal vesicle
(2)Prostate 3 gland
(3)Testes
(4)Penis.

b.Write functions of any three of them.
Ans:(1)Seminal vesicle:- To provide a secretion that is a part of semen and that nourishes the sperms.
(2)Prostate gland:- To secrete prostate fluid which is one of the components of semen.
(3)Testes:-To produce sperm and hormone testosterone.
(4)Penis:-To ejaculate semen into vagina.

(iv)Draw a neat labelled diagram of human female reproductive system and write functions of any two of them.
Ans:

Functions: (1)ovary:-To produce oocyte and hormonee estrogen and progesterone.
(2)Uterus:-(i)Nurturing the fertilized ovum till it develops into foetus and till the baby is ready for birth.
(ii)To push the baby at the time of the birth.
(3)Vagina:-(i)It provides the path way to the baby during the birth.
(ii)It is also the pathway for the menstrual flow.
(iii)It receives the sperms ejaculated by the penis of man.

Environmental management

Important points:
1)Ecosystem is formed by biotic and abiotic factors and their interaction with each other.
2)Biotic factors are animals, plants and-microorganisms where as abiotic factors are air, atmosphere, water, land etc.
3)The science that deals with the study of interactions between biotic and abiotic factors of the environment is called ecology. Basic functional unit used to study the ecology is called as ecosystem.
4)Air pollution, water pollution and soil pollution are the three types of the pollution of environment.
5)Environmental conservation is our social responsibility, so that the coming generations can live comfortably.
6)Different laws like Forest Conservation Act, 1980 and Environmental Conservation Act, 1986 are made to conserve the environment.
7)To protect the wild life wildlife Protection Act, 1972 has been enacted.
8)Biodiversity occurs at three different levels:
(i)Genetic diversity
(ii)Species diversity and
(iii)Ecosystem diversity
9)Biodiversity can be conserved by (i)Protecting rare species. (ii)Establishing national parks and sanctuaries.
(iii)Declaring some regions as bioreserves.
(iv)Projects for conservation of special species.
(v)Conserving all plants and animals.
(vi)Observing the rules.
(xii)Maintaining the record of traditional knowledge.
10)Our role In environment conservation is
(i)Conservation of resources
(ii)Controlling the activities which harm the environment
(iii)Revival of harmed factors of environment
(iv)Preserving the remaining resources and remedies to prevent further loss
(v)Prevention of further harms
(vi)Creating awareness.
11)Following is the classification of threatened species:
(i)Endangered species
(ii)Rare species
(iii)Vulnerable species
(iv)Indeterminate Species.

Exercise
Q.1.(A)Use the correct option and fill In the blanks.
(i) ______is a producer.
(a) Grasshopper (b)Frog (c)Snake (d)Grass

(ii)Which organism would fit in the following food Chain? Insects -> chicken -> snake -) ______.
(a) mouse (b)eagle (c)deer (4)frog

(iii) Air, water, soil and _____ are some of the abiotic factors of the ecosystem.
(a)minerals (b)animals (c)decomposers (d)green plants

(iv)_______ is observed as world Biodiversity Day.
(a) 5th June (b) 11th July (c) 22th December (d) 22th May

(v)The forests conserved in the name of god are Called as ________.
(a)sanctuaries (b)sacred groves (c)botanical garden (d)national park

Ans: (i) Grass (ii) eagle (iii) minerals (iv) 22th May (v) sacred groves.

Q.1.(B)Answer the following questions.
*(i)A bird building nest on a tree feed upon the fishes in nearby pond. Whether this bird is part of both i.e. tree as well as pond ecosystem?
Ans:As the bird has interactions with both the ecosystems namely tree and pond, it is a part. of both of them.

*(ii)If frog population declines all of a sudden, what will be the effect on paddy crop?
Ans: Frogs feed upon grasshoppers and grasshoppers feed upon paddy crop. So, if frog population declines, number of grasshoppers will increase indefinitely and the paddy crop will be destroyed.

*(iii)If frog population declines, number of which consumers will decline and which will increase?
Ans:The number of tertiary consumers (snakes) will decline and number of primary consumers(grasshoppers) will increase.

*(iv)If frog population declines all of a sudden, what will be overall effect on that ecosystem?
Ans:There will be imbalance in the ecosystem. The grasshoppers will increase and after some time may fall short of paddy crop. Also, the consumers feeding on paddy crop will starve. The consumers feeding on frogs will also starve.

*(v)What is an environment?
Ans:Physical, chemical and biological factors affecting the living organisms in any possible way is collectively called as environment. It is the condition in surrounding.

*(vi)What is included in-environment?
Ans:Environment includes many biotic(e.g. animals, plants), abiotic (e.g.air water, soil), natural (e.g.forests, mountains) and artificial factors (e.g.dams,industries).

*(vii)How do butterflies contribute to environmental balance?
Ans:(1)They help In the pollination of various plants. This helps In maintaining many species.
(2)They control the population of many weeds and insects which they feed upon.

*(viii)Write the names of biodiversity hot spots.
Ans:(1)Jungles of eastern region
(2)Western ghat.

Q.2.(A)Answer the following questions.
(i)Reorganize the following food chain. Describe the ecosystem to which it belongs. Grasshopper–Snake–Paddy field–Eagle–Frog.
Ans:(1)Reorganized food chain: Paddy field Grasshopper–Frog–Snake–Eagle.
(2)it belongs to the ecosystem which includes the paddy field and the surrounding trees and sky where the eagles live.

*(ii)Write the factors affecting environment.
Ans:Following are the factors affecting the environment:(1)Physical factors e.g. Air, water, vapour, minerals, soil, sunlight etc.
(2)Chemical factors e.g. inorganic substances like hydrogen, oxygen, calcium, iron etc. and organic substances like carbohydrates, proteins, fats etc.

*(iii)Why do the human beings have important place in environment?
Ans:(1)With the help of intelligence, memory and imagining ability etc. humans always try to dominate the nature.
(2)They utilize all the natural resources possible to live a comfortable life and snatch from the nature as much as possible.
(3)This is resulting into the imbalance in the environment and harm to the environment.
(4)At the same time, it is humans who can control this and conserve the environment with conscious efforts. So, the human beings have important place in environment.

*(iv)How can the biodiversity be conserved?
Ans:(1)By protecting the rare species of organisms.
(2)By establishing national parks and sanctuaries.
(3)By declaring some regions as bioreserves.
(4)By Undertaking projects for conservation of special species.
(5)By conserving all plants and animals.
(6)Observing the rules enacted by the Government time to time.
(7)Maintaining record of traditional knowledge regarding various species.

*(v)What do we learn from the story of Jadav Molai Peyang?
Ans:(1)If we show determination, we can do miracles.
(2)A single man can totally change the situation if he takes initiative and does hard work and shows perseverance.
(3)if you really do the great work, the government authorities also take cognizance of it and help you in all ways.

*(vi)What is ecosystem? Which are its different components?
Ans:(1)Biotic and abiotic factors occupying a definite geographical area and their interactions collectively are called an ecosystem. e.g. a small pond, a forest etc.
(2)Its components are (a)Biotic components e.g. animals, plants, microbes and (b)abiotic components like air, soil, water, mountains etc.

*(vii)What may be the relationship between lake and birds on tree?
Ans:(1)The birds on the tree are fed on the fish which are there In the lake.
(2)Birds drink water form the lake.
(3)The trees which are the habitats of birds are also getting water from the lake.

*(viii)What is the difference between food chain and a food web.
Ans:Food chain is a simple chain of the organisms showing who is fed on whom. Where as a food web is a complex network consisting of many food chains clubbed together. In a food web, we can observe that a single organism is a food of more than one organisms and at the same time an organism is fed on more than one organisms.

*(ix)Which are different trophic levels?
Ans:(1)Producers (2)Herbivores (Primary consumers)(3)Carnivores (secondary consumers)(4)Apex carnivores (Tertiary consumers).

*(x)What is energy pyramid?
Ans:(1)Energy pyramid shows the energy flow from one trophic level to the next trophic levels.
(2)Only 10% energy is passed on to the next trophic level.
(3)The number off organisms also decreases form the lowest level to the highest level.
(4)If this is represented pictorially, it 10°ks like a pyramid This Is called as energy Pyramid.

*(xi)What will happen if number of consumers in environment goes on increasing gradually?
Ans:If number of consumers in environment goes on increasing gradually and the number of producers remains the same then the consumers will start experiencing the shortage of food and they will have to face starvation.

*(xii)Which are the types of pollution?
Ans:The types of pollution are:
(1)Air pollution
(2)Water pollution
(3)Soil pollution
(4)Sound pollution
(5)Radioactive pollution.

*(xiii)What do we mean by natural and artificial pollution?
Ans:(1)The pollution caused by the natural events is called natural pollution. e.g. Pollution due to the eruption of volcano, forest fires and ozone.
(2)The pollution caused due to the man-made activities is called artificial pollution. e.g. pollution due to the burning of fuels, plastic articles, chemical industries etc.

*(xiv)Complete the following chart:

*(xvi)Which cycles are operated In environment? What is their importance?
Ans:(1)Following cycles are operated in environment:(i)Carbon cycle (ii)Oxygen cycle (iii)Nitrogen cycle etc.
(2)The nutrients required for various organisms are taken from the environment.
(3)When these organisms die, the nutrients are given back to the environment. Thus, these nutrients are available for the new organisms and they do not remain blocked in the dead organisms. Therefore, these cycles are important.

Q.2.(B)Write Short notes.
Ans:*(i) Environmental conservation:-(1)Environmental pollution has harmful effects on human beings and other organisms.
(2)It affects the plants and crops
(3)So, it is necessary to conserve environment.
(4)Environment can be conserved by (i)conserving biodiversity (ii)pollution control (iii)Avoiding deforestation (iv)plantation of trees (v)use of green energy etc.
(5)Every citizen has to contribute towards the conservation of environment.

*(ii)Chipko Movement of Bishnoi:-(1)It was a forest conservation movement.
(2)In this movement, people embraced the trees to prevent them from being cut.
(3)This movement took place in Khejarii village of Rajasthan.
(4)About 363 bishnois sacrificed their lives to save khejri trees.
(5)Later, this type of movement tookplace at various places to save trees.

*(iii) Biodiversity:-(1)Biodiversity is the richness of living organisms in nature due to the presence of varieties of organisms, ecosystems and genetic variations within a species.
(2)Occurs at three different levels: (i) Genetic diversity (ii)Species diversity (iii)Ecosystem diversity.
(3)Biodiversity can be conserved by (i)protecting the rare species (ii)by establishing national parks and sanctuaries (iii)by declaring some regions as bioreserves (iv)by undertaking projects for conservation of special species (v)conserving all plants and animals (vi)by observing the rules enacted for biodiversity conservation (vii) by maintaining record of traditional knowledge.

*(iv)Sacred groves:-(1)The forest conserved in the name of the god and considered to be sacred is called as sacred grove.
(2)These are the sanctuaries conserved by the society and not by the government forest department.
(3)As it has been conserved in the name of god, it has special protection. No body cuts the trees due the religious belief.
(4)These forests are present in Western Ghats and other regions of india.
(5)There are about 13000 sacred groves in India.

*(v)Disaster and its management:-(1)Disaster management is action implemented through proper planning, organized activity and co-ordination.
(2)It includes: (i)Prevention of losses and danger (ii)Imroving tolerance (iii)Providing relief from disaster, minimising the intensity and extent of harm(iv)Preparation to face the disaster.(v)Immediate action in the disaster situation.(vi)Assessment of damages and intensity of the disaster.(vii)Arranging rescue work and help.(viii)Rehabilitation and rebuilding(ix)Warning system to forecast the occurrence of disaster.

Q.3.(A)Answer the following questions.
*(i)Explain the following statement ‘we have got this earth planet on lease from our future generations and not as an ancestral property from our ancestors’.
Ans:(1)The way we have right to use natural resources, our future generations also have the same right. So, it is our responsibility to use natural resources. Judiciously and ensure that the coming generations also can avail them.
(2)When we handover the earth to the next generation, it should at least be in the state in which we got it from previous generation. So, it is essential that we conserve the environment and keep it free from pollution so that future generations also can live comfortably.
(3)It is our responsibility that the developments we make are sustainable and eco-friendly. As we are taking care of our needs we should always keep in mind the future requirements of coming generations.

*(ii)How will you justify that overcoming the pollution is a powerful way of environmental management?
Ans: (1)For environmental management, the factors affecting the environment adversely must be controlled.
(2)Various types of pollution are affecting the habitats of different organisms e.g. water bodies, soil, forests, valleys etc.
(3)Due to pollution, the food on which organisms feed also gets affected. e.g. Cows, fish etc. swallow plastic material along with their food which is harmful for them
(4)Pollution of air also affects the organisms causing various respiratory problems.
(5)If pollution is overcome such problems will never arise and the environment will be conserved.

*(iii)Which projects will you run in relation to environmental conservation? How?
Ans: (1)Avoid using plastic as far .as possible. It will reduce the pollution of soil and water.
(2)Reuse the items which are reusable e.g. papers, envelopes etc. As these are made from plants, less plants will have to be consumed for this purpose.
(3)Avoid felling the trees.
(4)Plantation of trees.
(5)Proper disposal of garbage. It will avoid the pollution of the surroundings.
(6) Proper usage of various resources like petrol whose burning creates the pollution of air.
(7)Maximum use of green energy e.g. solar energy which will reduce the pollution.

*(iv)Write the types and examples of biodiversity.
Ans: There are three types of biodiversity: (1)Genetic diversity:-Occurrence of diversity among the organisms of same species is genetic diversity. e.g. Each human being is different from other. Possibility of wiping out the species arises if there is decrease in the diversity within the species whose members invoice in sexual reproduction.
(2)Species diversity:- In numerable species of organisms occur in the nature. This is called as species diversity. e.g. various species of plants, animals and microbes.
(3)Ecosystem diversity:- Many ecosystems are present in each region. Ecosystem is formed through the interaction between plants, animals, their habitat and changes in the environment. Each ecosystem has its own characteristic animals, plants, microbes and abiotic factors. Further, ecosystem can be natural or artificial.

*(v)Which are the reasons for endangering many species of plants and animals? How can we save those?
Ans: Reasons for endangering many species:-(1)Mining (2)Construction of dams (3)Indiscriminate use of water (4)Deforestation (5)Excessive fishing (6)Illegal hunting (7)Pollution (8)Industrialisation
How to save endangering species:- (1)By protecting the rare species of organisms.
(2)By establishing national parks and sanctuaries.
(3)By declaring some regions as bioreserves.
(4)By undertaking projects for conservation of special species.
(5)By conserving all plants and animals.
(6)Observing the rules enacted by the government time to time.

*(vi)Why is it said that pollution control is important?
Ans: (1)Following diseases can be caused due to air pollution: (i)Diseases like Bronchitis, Pneumonia and Asthma. (ii)Chronic pulmonary disease (iii)Cardio vascular disease (iv)Lung cancer (v)Premature death.
(2)Following diseases can be caused due to water pollution: (i)Cholera (ii)typhoid (iii)diarrhoea (in) dysentery (v)hepatitis (vi)polio (vii)jaundice. Also, aquatic life is harmed due to water pollution.
(3)Due to soil pollution, the agricultural produce is affected.
(4)To avoid all these harmful effects pollution must be controlled. Therefore it is said that pollution control is important.

*(vii)What are the meanings of following symbols? Write your role accordingly.

Ans: (1)The symbol stands for ‘Recycling’. We should not throw the articles here and there which can be recycled.
For example, plastic articles. They must be handed over to proper agencies Who initiate recycling.
(2)The symbol stands for ‘Turn off the tap and save water’. We should close the taps which are kept oben by other persons unknowingly. We also should close the taps properly ourselves when not required. The leaking taps must be repaired immediately.
(3) This symbol stands for ‘Solar energy’. We must make use of solar energy wherever possible e.g. solar cookers, solar water heaters.

*(viii)Which are the types of consumers? What are the criteria for their classification.
Ans: (1)The types of consumers are (i)Primary consumers (Herbivores) (ii)Secondary consumers (Carnivores) (iii)Tertiary consumers or apex consumers (Carnivore’s) (iv)omnivores (Mixed consumers).
(2)The criteria for the classification is the trophic level which the consumer feeds upon.

*(ix)Observe the following figure and answer the questions that follow:
(a)Write the name and category of each of the component shown in the picture.
Ans: (1)Grass/ Crops (Producers) (2)Grass hopper (Primary consumer) (3)Frog (secondary consumer) (4)Snake (Tertiary consumer) (5)Eagle (Apex consumer) (6)Decomposers / scavengers.

(b) What is necessary to convert this picture into food web? Why?
Ans: (1)Food web is a complex network depicting who feeds on whom and who is fed by whom. One organism can be eaten by more than one organisms and one organism can eat more than one organisms.
(2)To represent this complex network, more organisms which are fed on grass/crops must be added to the picture. Similarly, more organisms should be added which are 5 eaten by frog. This type of addition must be done at every level possible to convert the picture into a food web.

*(x)Complete the following chart:

Towards Green Energy

Animal Classification

Introduction to Microbiology

Cell Biology and Biotechnology

Social health

Disaster Management