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Chapter Review:

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• Full Form of DNA is Deoxyribo Nucleic Acid.
• In fission, many bacteria and protozoa simply divide into two or more daughter cells.
• Roots, stems and leaves of some plants develop into new plants through vegetative propagation.
• Simple animals like Hydra and Planaria can be cut into any number of pieces and each piece grows into a complete organism. This is known as regeneration.
• New plants are grown by removing tissue or separating cells from
  the growing tip of a plant is called Tissue culture.
• Unisexual flowers may be papaya and watermelon.
• The transfer of pollen grains from the stamen to the stigma in the same flower is called self pollination.
• The transfer of pollen grains from the stamen to the stigma from one flower to another flower is called cross pollination.
• The seed contains the future plant or embryo which develops into a seedling under appropriate conditions. This process is known as germination.
• Sperm formation requires a lower temperature than the normal body
  temperature.
• The two oviducts unite into an elastic bag-like structure known as the
  uterus.
• Male sex hormone is testosterone.
• Female sex hormone is estrogen.
• The developing embryo will also generate waste substances which can be removed by transferring them into the mother’s blood
  through the placenta.
• The lining slowly breaks and comes out through the vagina as blood and mucous. This cycle takes place roughly every month and is known as menstruation.
• The bacterial infections such as gonorrhoea and syphilis, and viral infections such as warts and HIV-AIDS.
• Contraceptive devices such as the loop or the copper-T are placed in the uterus to prevent pregnancy.
• The male reproductive system in human beings consists of testes which produce sperms, vas deferens, seminal vesicles, prostate gland, urethra and penis.
• The female reproductive system in human beings consists of ovaries, fallopian tubes, uterus and vagina.

Text-book Questions

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Page no. 128 

Q1. What is the importance of DNA copying in reproduction?

Answer: The basic event of reproduction is DNA. to replicate. DNA Cells use various chemical reactions to replicate. In this way DNA in the germ cell Two replicas of DNA during reproduction Replication is very important for an organism's physical structure and design, which enables organisms to live in a specific location.

Q2. Why is variation beneficial to the species but not necessarily for the individual? 

Answer: Variation in organisms is beneficial for the species but it is not necessary for the individual, because the diversity in the organisms provides stability to the population of their species. Any one population is adapted to its niche, but in extreme circumstances, when a niche is no longer favorable to them, then these variations save them from the complete destruction of their population. There are some such organisms in their population which are able to resist those odd changes and they survive, but some individuals die from their population. Therefore, variations are beneficial for maintaining the survival of the population.

Page no. 133 

Q1. How does binary fission differ from multiple fission? 

Answer: binary fission
  1. In this the cells of the organism are divided into two parts.

  2. Cells in bifidation In some organisms such as Amoeba, cell division can take place from any plane whereas in organisms like Lesmania, cell division takes place from a fixed plane.

multiple fission

  1. In this the cells of the organism are divided into many parts.

  2. In multiple fission the organism divides into many daughter cells. For example - Plasmodium.

Q2. How will an organism be benefited if it reproduces through spores?

Answer: Spore is a special type of reproductive structure. Which are very light and due to many reasons these spores get separated from their bunch and spread here and there. These are the reproductive parts of the organism which are protected in adverse conditions due to their thick wall and start growing as soon as they come in contact with the moist surface. Hence, they grow only under favorable conditions.

Q3. Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?

Q4. Why is vegetative propagation practised for growing some types of plants?

Answer: Vegetative propagation is used to grow some plants.

(i) Plants which do not have the ability to produce seeds are propagated only by vegetative propagation.

(ii) Plants grown by this method start producing fruits and flowers in less time than those grown by seed.

(iii) Plants grown by this method have the same fruits and flowers as the parent plants.

Q5. Why is DNA copying an essential part of the process of reproduction?

Answer: Because-

(i) DNA The formation of a replica is the basic event of reproduction which is responsible for the biological development in the progeny organism.

(ii) DN ​​of the nucleus of the cell. a. Contains information for protein synthesis. DNA At the time of replication, the type of information involved in replication, the protein produced is also made of the same type.

(iii) Due to different proteins, there is diversity in the physical design of the organisms. The daughter cells, though similar, differ from each other in some way or the other.

(iv) DNA There is some change in the replication of the original DNA, which are not basically identical, so after reproduction these generations have the ability to tolerate.

Page no. 140

Q1. How is the process of pollination different from fertilisation?

Answer: Pollination process -

(i) The transport of pollen grains from pollination to the stigma is called pollination process.

(ii) Cells are not attached to it.

(iii) Often has to wait for the carriers to complete this action.

fertilization -

(i) The combination of male and female gametes is called fertilization.

(ii) Male and female cells are involved in this.

(ii) This verb is conjunct.

Q2. What is the role of the seminal vesicles and the prostate gland?

Answer: Sperm and prostate gland are present in male and their secretion nourishes the sperms. The prostate gland also secretes a fluid. Through this secretion, sperms are transferred to the female reproductive system, so they are important male glands for reproduction.

Q3. What are the changes seen in girls at the time of puberty?

Answer: Changes seen in girls at the time of puberty -

(i) Hair growth around the genitals.

(ii) Increase in the size of the thorax.

(iii) the onset of menstruation.

Q4: How does the fetus get nourishment in the mother's body?

Answer: The fetus is nourished in the mother's womb. Receives nourishment from mother's blood. It is attached to the mother by a tissue called placenta and through this it receives water, glucose, oxygen and other nutrients.

Q5: If a woman is using Copper-T, will it protect her from sexually transmitted diseases?

Answer: No, Copper-T does not prevent the transfer of sexually transmitted diseases. Copper-T only prevents pregnancy.

Exercises:

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Q1. Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.

Answer: (b) yeast

Q2. Which of the following is not a part of the female reproductive system in human beings?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube

Answer: (c) Vas deferens 

Q3. The anther contains
(a) sepals.
(b) ovules.
(c) carpel.
(d) pollen grains.

Answer: (d) pollen grains. 

Q4. What are the advantages of sexual reproduction over asexual reproduction?

Answer: The advantages of sexual reproduction over asexual reproduction are as follows: 

(i) There are much variations in the organisms reproduced by sexual reproduction than of the asexual reproduction. 

(ii) It plays an important role in speciation. 

(iii) There are much options to combine of new variations of DNA. 

(iv) The new indivisual is differ to parent in physically but similar at DNA level. 

(v) The sexual reproduction encourrages much new features in offspring as it occurs by fission of two difference gamates while there is no so happens in asexual reproduction.   

Q5. What are the functions performed by the testis in human beings?

Answer: Function of testis in human beings:

(i) It produces male gamate sperms. 

(ii) It releases male sex hormone testosterone. 

Q6. Why does menstruation occur?

Answer: A girl with puberty performs menstruation when an egg does not fertilise. After releasing ovum(egg) comes in fallopian tube and if here it comes in the contact of male gamate sperm the fertilisation takes place but if fertilisation does not take place it comes down in the uterus and after 3 to 4 days it gets degenerated and mixed with blood and mucus comes out of uterus. This is called menstruation and it occurs after every 28 days.    

Q7. Draw a labelled diagram of the longitudinal section of a flower.

Answer: 

Q8. What are the different methods of contraception?

Answer: There are following contraception methods: 

(i) Barrier methods - These methods are used outside the body ie on the upper skin eg - condom for male, diaphragm for female. This does not allow the sperm to meet the female's ovum.

(ii) Chemical methods: These methods are used by the female. Females can prevent pregnancy with oral pills. Oral pills especially cause changes in the hormones of the body, but sometimes they also have bad effects.

(iii) Loop or Copper-T: Pregnancy can also be stopped by installing in the uterus.

Q9. How are the modes for reproduction different in unicellular and
multicellular organisms?

Answer: Single-celled organisms have simple structure, so asexual reproduction takes place in them and they do not have special organs for reproduction. There are two types of reproduction in these - double fission and multiple fission. Multicellular organisms have reproductive systems due to complex structures, so sexual reproduction occurs in them as well as asexual.
Q10. How does reproduction help in providing stability to populations of species?

Answer: The basic structure of reproduction makes DNA replication. Cells Different chemical reactions Two copies of DNA are formed, it is responsible for the structure and pattern of the organism, these copies of DNA are separated and 'divided'. and forms two cells. In this way some variation comes which is beneficial for the existence of the species
Q11. What could be the reasons for adopting contraceptive methods?

Answer: Pregnancy devices are adopted to prevent pregnancy. Organisms perform reproductive activity and increase the growth of living beings, thus if this process continues continuously, then the population on the earth explodes, apart from this, there is an adverse effect on the woman's body at the time of conception. So more often this action can be harmful for him. Thus contraceptive devices are absolutely necessary.

Chapter - 8.  How do Organisms Reproduce?

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Q1.What are the significances of reproduction?

Answer: 

.(i) continuation of life

(ii) perpetuation of species

(iii) replacement of individual

(iv) variation and transfer of variation.

Q2.Why do we find variations in the offspring of parents although they have taken birth from the same parents?

Answer: Variations are differences found in morphological, physiological and other traits of individuals belonging to the same organism, race or family. They develop due to

(i) faulty DNA replication

(ii) Crossing over

(iii) Chance separation of chromosome during separation

(iv) Chance combination during fertilisation

(v) Mutation.

Q3.Why variations are considered extremely important?

Answer: 

.(A) Pre adaptation -Variation function as pre adaptation to environmental changes like increase or decrease in temperature, drought, antibiotic resistance, pesticide resistance etc.

( B) Individuality- As variation provides individuality we recognise each other.

(C) Evolution-Provides raw material for evolution or formation of new species.

Q4.Differentiate between regeneration and fragmentation?

Answer: 

Regeneration	Fragmentation
1. This type of reproduction is seen in fully differentiated organisms.  2. It is carried out by specialised cells, which proliferate and form mass of cells. From mass of cells, different cells undergo changes to become various cell types and tissues. These changes take place in an organise sequence. E.g.-Hydra, Planaria.	1. The type of reproduction is seen in multicellular organisms with relatively simple body organisation.  2. No specialised cells involves in this process. E.g. Algae, Fungi, Bryophytes.

Q5.Why is regeneration not same as reproduction?

Answer: Because organisms would not normally depend on being cut up to be able to reproduce.

Q6.How will an organism be benefited if it reproduces through spores?

Answer: The spores are covered by thick resistant walls due to which they pass through unfavorable conditions of drought, high or low temperature. Being small they can disperse long distances by air.

Q7.Which part of plant is considered as the reproductive part? Draw the L.S of labeled diagram of reproductive part showing the male and female reproductive organ.

Flower. see text book diagram figure 8.7

Q8.Distinguish between self and cross pollination.

Answer:

Self pollination-It is the transfer of pollen grains from anther to stigma of same flower.

Cross pollination- It is the transfer of pollen grains from anther of one flower to stigma of another flower. The transfer is accomplished by an external agency like wind, water, insect or birds.

Q9.Differentiate pollination and fertilization.

Answer: 

Pollination-It is the transfer of pollen grains from anther to stigma and this process precedes fertilisation.

Fertilisation-It is the fusion of male and female gametes that occur after fertilisation.

Q10.Explain the post fertilization changes in flower.

Answer: 

The changes are as follows: 

(i) Zygote divides several times to form an embryo within ovule.

(ii) Ovule changes into seed having tough seed coat

(iii) Ovary changes into fruit.(iv)Sepal, petal, stamen, style and stigma shrivel and fall off.

Q11.What are the advantages of seed formation?

Answer: 

(i) Dormant embryo and tough seed coat best suited to pass through unfavorable seasons.

(ii) Easily dispersed to long distances as they are small and light.

(iii) As seeds remain dormant, so edible seeds can be stored for later use.

Q12.Give the labeled diagram of
a. Germination of pollen on stigma.
b. Seed Germination.
c. Structure of seed.

Answer: See text book diagram.

Q13.What are the similar changes observed in boys and girls at puberty?

Answers: The following similar changes observed in boys and girls at puberty. 

(i) Hair-Growth of hair in arm pits and genital area between the thighs.

(ii)Genital area- Becomes darker.

(iii) Body hair-Thinner hair on legs, arms and face.

(iv)Skin-Becomes oily, appearance of pimples mainly on face.

(v)Awareness of body- Children become conscious and aware of their own bodies as well as those of others.

Q14.What are the different changes that occur in boys and girls during puberty?

Answer: 

Girls- The changes occur in response to hormone estrogen.

(i) increase of breast size

(ii) darkening of skin nipples

(iii)beginning of menstruation

(iv)broadening of pelvis

(v) fat deposition on face, buttocks and thigh.

Boys- The changes occur in response to hormone testosterone.

(i) slow growth of thick hair on face(moustaches, beard)

(ii) cracking of voice

(iii) enlargement of testes, scrotum, penis.

(iv) Erect of penis either in day dreams or at night.

Q15.Define Puberty?

Answer: The period when reproductive maturity begins to appear is called puberty.

Q16.Distinguish between primary and secondary sex organs?

Answer: 

(I) Primary sex organ-Sex organ which produce germ cells or gametes and sex hormones. Male-testes, females-ovaries.

(ii) Secondary sex organs-The sex organs which conduct and nourish the gametes.

Male-vasa differentia, penis, seminal vesicles, prostrate gland.

Female- fallopian tube, uterus, vagina

Q17.What are two important functions of testes and ovary?

Answer:

Testes-

(i) produce sperms

(ii) secrete hormone testosterone.

Ovaries-

(i) produce ovum

(ii) secrete hormone estrogen.

Q18.Why are human testes extra abdominal?

Answer: Testes are extra abdominal because it acts as thermo regulator keeping a temperature 1-3 degree Celsius below that of body, essential for development of sperm.

Q19.What are the functions of testosterone and estrogen?

Answer: 

Testosterone-Regulate sperm formation. Development of secondary sexual characteristics in males i.e., changes appear in boys at puberty.

Estrogen- Regulates ovum formation. Development of secondary sexual characteristics in females.

Q20.Distinguish between male and female germ cell.

Answer:

Male germ cell-

(i) smaller size

(ii) active and motile

(iii) contains genetic material in a tiny body and a long tail.

Female germ cell-

(i) bigger size

(ii) passive and nonmotile

(iii) contains nucleus and cytoplasm .Nucleus contains genetic material.

Q21.Where fertilization does takes place in case of human oviduct or fallopian tube?

Answer: Oviduct or fallopian tube

Q22.What is placenta? What is its function?

Answer: Placenta is a disc shaped structure which is the vital connection between fetus and mother. It provides glucose and oxygen from to embryo. It transfers waste of embryo to mother’s blood.

Q23.What happens when egg is not fertilized?

Answer: 

(i) Ovary releases one egg every month and the uterus prepares itself to receive the fertilised egg.

(ii) To receive the zygote its lining become thick, spongy for nourishing embryo.

(iii)If the egg is not fertilised, this lining is not needed any longer.

(iv) So the lining slowly breaks and comes out through vagina as blood and mucus, this is called menstruation.

(v) This cycle takes place every month and menstruation starts for 2-8 days.

Q24.The marriageable are of male and female is 21 years and 18 years respectively, the rule is made by government, although the sexual maturation take place in them earlier. Why?

Answer: Sexual maturation is a gradual process. It occurs while the general body growth is still going on. So sexual maturation does not mean that body and mind is ready for sexual acts and bringing up children.

Q25.What are the adverse effects of early marriage?

Answer: (i) Teen age couples cannot bring up their children.

(ii) Reproduction may affect the health of mother as well as child.

(iii) May bring deformity in children.

(iv)Young couple cannot peruse studies, nor can they have a carrier.

Q26.What is reproductive health?

Answer: It is the state of physical, mental and social fitness to lead a responsible, safe and satisfying reproductive life.

(i) It provides awareness regarding fertility regulating method.

(ii) Family planning.

(iii) Prevention of STD.

(iv) Manage disorders related to reproductive system by getting them treated at the earliest.

Q27.What are the various types of contraception?

Answer: Prevention of pregnancy is called contraception. The technique used in preventing the occurrence of pregnancy is called contraceptive devices.

(i) Mechanical Barrier method-It prevents the entry of sperm to uterus or reach to egg. E.g. condom (males), cervical cap (females), diaphragm.

(ii) Hormonal method-It changes hormonal balances, so that eggs are not released and fertilisation does not occur. These are oral pills.

(iii)Surgical method-It prevents passage of sperms in males and ova in females. It is of two types. (i) Tubectomy-In this oviduct is blocked by which ova cannot be released. (ii)Vasectomy- In this vasadeferntia of males is blocked. This prevents passage of sperms from testes to semen. Loop or copper T-It is placed in uterus of female which prevents fertilisation.

 

Additional Questions With Solutions

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Q1. A couple wants to space the birth of their second child. Suggest one preventive method which could be observed 
(a) By the husband (b) By the wife for the same.
Ans: (a) Use of condoms by the husband
(b) Use of oral pills or loop or Copper-T by the wife.
Q2. A girl attains her puberty at the age of 11 years and a boy at 13 years but, still they are asked to refrain from sex, why? 
Ans: They are asked to refrain from sex because:-
(i) They are not physically, emotionally mature enough to be able to bear the responsibility of the child.

(ii) They may suffer from reproductive tract infections.
Q3. A pregnant woman visits a doctor to determine the sex of her child. The doctor refused to perform the test. Why is she being denied? 
Ans: The doctor refused to perform the test in order to prevent female foeticide which leads to an alarming decline in child sex ratio.
Q4. Blue prints of body design are stored in the DNA. Why? 
Ans: The chromosomes present in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA molecule. The DNA is the information source for making proteins. Thus, blueprints of the body design are stored in the DNA.
Q5. Producing individuals by parents consume a lot of energy. So, why should an individual organism waste energy in the process, it does not need to stay alive?
Ans: Reproduction, unlike other life processes is not essential to maintain the life of an individual organism. But it is essential for providing stability to the population of species.
Maintaining the species is essential for maintaining balance in nature.
Q6. Protozoan reproduce by binary fission as well as by multiple fission. In your opinion which process is better and why? 
Ans: Multiple fission is better than binary fission because:-
1. More number of individuals is produced.
2. It helps to tide over unfavourable conditions.