Please refer to VBQs for Class 10 Science How do the Organisms Reproduce. All value based questions for English Class 10 have been provided with solutions. We have provided below important values questions and answers. Students should learn these solved VBQs for Class 10 Science as these will help them to gain more marks and help improve understanding of important topics.
How do the Organisms Reproduce VBQs Class 10 Science with Answers
Multiple Choice Questions
Question. Priya was writing some statements; help her to choose the correct one. m:
(a) The existing organisms are called parent and the new organisms produced by them are called offspring.
(b) The production of new organisms from a single parent without the involvement of sex cells or gametes is called sexual reproduction.
(c) The production of a new organism from two parents by making use of their sex cells or gametes is called asexual reproduction.
(d) All the above
Question. In the last year board examination Rahul was asked a question where he had to choose the statement which was /were incorrect. Will you be able to answer the questionnswer This Question?
(a) In vegetative propagation, new plants are obtained from the parts of old plants without the help of any reproductive organs.
(b) It is necessary to plant the whole potato tuber in the ground to produce the new potato plants.
(c) Bryophyllum plants can be reproduced by vegetative reproduction by using either a piece of its stem or its leaves.
(d) The green grass grows in the fields after range from the dry, old stems of grass plants present in the fields, by the method of vegetative propagation.
Question. Variations occur as a result of
(a) Asexual reproduction
(b) Vegetative propagation
(c) Sexual reproduction
Question. Along the path of the vas-deferens the secretions of which gland provide nutrition to the sperms?
(a) Prostate glands
(b) Seminal vesicles
(d) Urinary bladder
Question. The embryo in humans get nourishment from mother’s blood with the help of special tissue called
Question. The fertilization of human egg by sperm takes place in
Question. In case the ova does not fertilise which of the following events will take place?
Question. Fruits are formed from
Question. The number of chromosomes in parents and off springs of a particular species remains constant due to
(a) doubling of chromosomes after zygote formation
(b) halved of chromosomes during gamete formation
(c) doubling of chromosomes after gamete formation
(d) halving of chromosomes after gamete formation
Question. How do spores develop into Rhizopus?
(a) Spores divide and grow into new individual
(b) Spores combine with other spores and grow
(c) Spores enlarge in size for the growth of new individual
(d) Spores land on other organisms and increase with their growth in size
Question. In rhizopus tubular structure bearing sporangia at their tips are called __________.
Case Study Based Question :
Read the following and answer the questions:
Menstrual cycle is the cycle of events taking place in female reproductive organs, under the control of sex hormones, in every 28 days. At an interval of 28 days, a single egg is released from either of two ovaries. Regular menstrual cycle stopped abruptly in a married women. She got herself tested and was happy to discover that she is pregnant with her first baby.
Question. Why menstruation stops in a pregnant female?
(a) The egg gets fertilised so need not to be expelled out of body
(b) Ovulation stops during pregnancy and so do menstruation
(c) Thick uterine lining is needed for proper development of embryo, so that it is retained
(d) All of these
Question. Select the correct sequence of acts that leads to pregnancy in a female.
A. Fertilisation of egg
C. Formation of zygote
(a) D ⇒⇒C ⇒⇒B ⇒⇒A
(b) B⇒⇒ A⇒⇒C⇒⇒D
(c) A ⇒⇒ B⇒⇒ C⇒⇒ D
(d) D⇒⇒ C⇒⇒ A ⇒⇒B
Question. How is a zygote different from embryo?
(a) Zygote is formed by repeated division of embryo
(b) Zygote is formed by fusion of sperm and egg whereas embryo is formed by fusion of zygote with other zygote
(c) Zygote is single celled but embryo is multicellular
(d) Zygote is formed by fertilisation but embryo is formed without fertilisation
Question. What change takes place in the uterus of a pregnant female?
(a) Uterine lining becomes thick and vascular
(b) Placenta develops which links the embryo to mother through umbilical cord
(c) Uterus lining containing lots of blood capillaries breaks down
(d) Both (a) and (b)
Short Answer Type Question
Question. What is the importance of DNA copying in reproduction?
Answer. DNA contains information for the inheritance of features from parents to next generation. DNA presents in nucleus of cells are the information source for making protein. If information is different, different protein will be made that lead to altered body design.
Question. (a) Name the parts 1 to 5 of human female reproductive system.
(b) Name the part in which fertilization takes place in the system
(b) Fallopian tube.
Answer. (a) 1 – fallopian tube,2— ovary,3 — Uterus, 4 — cervix, 5 — vagina.
Question. Surgical methods can be used to create a block in the reproductive system for contraceptive purposes. Name such parts where blocks are created in
(a) Males and Females.
(b) State any two reasons for using contraceptive devices.
Answer. (a) Vasa deferentia and Fallopian tubes.
(b) -Contraceptive devices are used to prevent pregnancy for
-Limiting size of family by spacing birth of children
-Avoiding unwanted pregnancy.
Question. Prenatal sex determination has been prohibited by law. State two reasons.
Answer. The test has been banned since due to desire of male child, there has been large scale female foeticide. This has resulted in declining female-male sex ratio.
Question. List the advantages of vegetative propagation.
Answer. The advantages of vegetative propagation are as follows
• It helps in the easy propagation of non–flowering plants.
• It helps in producing hybrids of various plants, with improved qualities.
• It helps in the propagation of a large number of populations in a very short duration.
• It helps in the propagation of plants that do not produce seeds or produce them in very small quantities.
Question. Name the female reproductive part of a flower. Which part of a flower develops into a seed and a fruit? Where are the male germ cell and female gamete present in the flower?
Answer. Female reproductive part of a flower is pistil. Ovary develops into fruit and ovule into seed. Male germ cell is present in pollen grain and female germ cell in the ovary.
Question. What is reproduction? Explain two advantages of sexual reproduction over asexual reproduction.
Answer. Reproduction: It is a (biological) process by which new individuals of the same species are produced by the existing organisms.
Advantages of sexual reproduction:
(i) Leads to stability of population of species.
(ii) Results in variations useful for the survival of species over time.
Question. State the basic requirement for sexual reproduction? Write the importance of such reproductions in nature.
Answer. Basic requirements in sexual reproduction are:
(i) Formation of gametes through meiosis.
(ii) Transfer of male gametes into the female body.
(iii) Fusion of male and female gametes. Process is fertilization.
(iv) Formation of offspring from a single celled zygote- Post fertilization changes.
The basic requirements for sexual reproduction to take place are involvement of two parents and fusion of haploid gametes. Importance of sexual reproduction:
Fusion of gametes results in genetic variations in the offspring. This promotes diversity of characters in offspring. These genetic variations, thus, lead to evolution of species as well as allow the organisms to become better adapted in the changing environment.
Question. What is sexual reproduction? List its four significance.
Answer. Two major processes namely formation of gametes and fusion of gametes constitute sexual reproduction.
Significance–(i) Incorporates the process of combining DNA from two different individuals during reproduction.
(ii) Increases genetic variation.
(iii) Promotes diversity in the offsprings.
(iv) Plays a role in the origin of new species.
Question. What is vegetative propagation? State two advantages and two disadvantages of this method.
Answer. Vegetative propagation is a mode of asexual reproduction in which new plants are formed from roots, stems, leaves and buds of the individual vegetative parts of the plants. e.g., eyes of potato.
(i) Offsprings are genetically identical and therefore useful traits can be preserved.
(ii) It is a rapid and economical method.
(i) New characters cannot be introduced.
(ii) The disease of the parent plant gets transferred to the offsprings.
Question. Name the two types of mammalian gametes. How are these different from each other? Name the type of reproduction they are involved in. Write the advantage of this type of reproduction.
Answer. Male gamete: sperm
Female gamete: ovum/egg
Sperms are motile and produced by male individual, ova/eggs are non-motile and produced by female individual.
Type of reproduction is Sexual reproduction Advantage: Generates more variations
Question. What is regeneration? Give one example of an organism that shows this process and one organism that does not. Why does regeneration not occur in the latter?
Answer. (i) Regeneration: Ability of organisms to give rise to new individual organisms from their body parts.
(iii) Amoeba / Rhizopus / Banana / Sugarcane / any other does not show regeneration.
(iv) Regeneration is carried out by specialized cells which are not present in non-regenerating organisms.
Question. What is multiple fission? How does it occur in an organism? Explain briefly. Name one organism which exhibits this type of reproduction.
Answer. Multiple fission: The process of reproduction in which many individuals are formed or produced from the parent cell.
In this process, the nucleus divides repeatedly to produce large number of nuclei. Each nucleus gathers a bit of cytoplasm around itself, develops a membrane around each structure.
Many daughter cells develop which on liberation grow into adult organism.
Plasmodium exhibits this type of fission.
Question. (a) Budding, fragmentation and regeneration, all are considered as asexual mode of reproduction. Why?
(b) With the help of neat diagram, explain the process of regeneration in Planaria.
Answer. (a) Because these methods involve only one parent / organisms are formed as a result of mitotic division / progeny (organisms) are similar in their genetic make up and no variations is seen.
Planaria can be cut into many number of pieces and each piece grows through specialized cells into a complete organism.
Question. Name the reproductive parts of an angiosperm. Where are these parts located? Explain in brief the structure of its female reproductive parts.
Answer. (i) Stamen and Carpel.
(ii) Located in the flower.
(iii) The female reproductive part is Carpel. It is made up of three parts–the bottom swollen part is ovary, middle elongated part is the style, terminal sticky part is stigma.
Question. Write the functions of the following parts of human female reproductive system:
(i) Ovary, (ii) Fallopian tube (iii) Uterus.
Answer. (i) Ovary: It produces eggs (ova) and female sex hormone estrogen and progesterone.
(ii) Fallopian Tube: The fallopian tube provides passage for the eggs (ova) to pass into the uterus by ciliary action of fimbriae It is the site for fertilisation.
(iii) Uterus: Uterus is the site of implantation of zygote and site of development of embryo.
Question. Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival-the one reproducing asexually or the one reproducing sexually? Justify your answer.
Answer. Any one of the following difference:
(i) In sexual reproduction, two opposite sexes are involved whereas in asexual reproduction, only one individual is involved.
(ii) In sexual reproduction, male and female gamete formation takes place whereas in asexual, no gamete formation occurs.
Sexually reproducing organisms have better chances of survival.
Because more variations are generated.
Question. What are the functions of testis in the human male reproductive system? Why are these located outside the abdominal cavity? Who is responsible for bringing about changes in appearance seen in boys at the time of puberty?
Answer. Functions of testis:
(i) Produce sperms.
(ii) Produces male hormone/ testosterone.
These are located outside the human body, as sperms need lower temperature than the normal body temperature to mature.
Question. What is carpel? Write the function of its various parts.
Answer. Carpel is the female reproductive part that produces egg cells.
Main parts of carpel are:
(i) Stigma being sticky in nature receives pollen grains during pollination.
(ii) Style connects the stigma and ovary thus, helping with the transfer of pollen through style to the ovary.
(iii) Ovary is the reproductive organ of carpel which produces the female gamete ovule.
Question. What happens when:
(a) Accidently, Planaria gets cut into many pieces?
(b) Bryophyllum leaf falls on the wet soil?
(c) On maturation sporangia of Rhizopus bursts?
Answer. (a) When Planaria gets cut into many pieces, each piece regenerates into a new Planarian organism.
(b) When Bryophyllum leaf falls on the wet soil, the buds that are present along the margin of the leaf will develop into new plants by the process known as vegetative propagation.
(c) When the sporangia of Rhizopus burst upon maturation, it releases spores which germinate into new mycelium in moist conditions.
Question. State briefly the changes that take place in a fertilized egg till birth of the child in the human female reproductive system. What happens to the egg when it is not fertilized?
Answer. Changes in fertilized egg:
(a) Zygote/fertilized egg starts dividing.
(b) Implantation of zygote in the inner uterine wall.
(c) Embryo starts growing with the help of the placenta which results in the development of the child.
(d) Birth of a child as a result of rhythmic contraction of the muscles in the uterus.
When egg is not fertilized, the inner lining of the uterus slowly breaks and comes out through the vagina as blood and mucous (Menstruation)
Question. Draw longitudinal section of a bisexual flower and label the following parts on it:
(i) Anther, (ii) Ovary, (iii) Stigma, (iv) Style.
4 correct labellings (i) Anther (ii) Ovary (iii) Stigma (iv) Style
Question. How do organisms, whether reproduced asexually or sexually maintain a constant chromosome number through several generations?
Explain with the help of suitable example.
Answer. (i) When organisms reproduce asexually, only mitotic divisions are involved and the chromosome number remains the same.
(ii) During asexual reproduction, the DNA (in the chromosomes) or the cells involved are copied and then equally divided among the two daughter cells. Thus, chromosome number remains unchanged.
(iii) In sexual reproduction, organisms produce gametes through a special type of division called meiosis or reductional division, in which the original number of chromosomes is reduced to half.
These two male & female gametes fuse to form the zygote and the original number of chromosomes is restored.
(iv) In sexual reproduction, specialized cells / germ cells with only half the number of chromosomes are formed. When these germ cells from two individuals combine to form a new individual, the original chromosome number is restored.
(v) Example: In humans, the parents (father and mother) each have 46 or 23 pairs of chromosomes. In the gametes, the sperm has half the number of chromosomes i.e., 23 and the egg also has 23 chromosomes. When the sperm and the egg fuse, the zygote has 46 or 23 pairs of chromosomes. Thus, the chromosome number remains constant.
Question. Define reproduction. How does it help in providing stability to the population of species?
Answer. Reproduction: It is a (biological) process by which new individuals of the same species are produced by the existing organisms.
(i) Populations of organisms live in well-defined places called niches in the ecosystem using their ability to reproduce.
(ii) Reproduction involves DNA copying which is the source of information for making proteins thereby controlling body design.
(iii) These body designs allow the organism to use a particular niche for the stability of the population of a species.
(iv) (Minor) variations may also lead to the stability of the species.
Question. What is placenta? Write any two major functions of placenta.
Answer. Placenta: A disc shaped organ or special tissue in the uterus of pregnant mammal, nourishing and maintaining the foetus through the umbilical cord.
Functions of Placenta:
(i) Provides large surface area for glucose and oxygen to pass from mother to the embryo.
(ii) Removal of waste generated in the developing embryo into the mother‘s blood.
Question. Define the term pollination. Differentiate between self pollination and cross pollination.
What is the significance of pollination?
Answer. The transfer of pollen grains from the anther to the stigma of a flower is known as pollination.
The two types of pollination are:
(a) Self pollination: When the pollen grains from the stamens of a flower fall on the stigma of the same flower, then it is called self pollination.
(b) Cross pollination: When pollen grains from the stamens of a flower fall on the stigma of another flower, it is called cross pollination.
Significance of pollination:
(i) It is a significant event because it precedes fertilization.
(ii) It brings the male and female gametes closer for the process of fertilization.
(iii) Cross-pollination introduces variations in plants because of the mixing of different genes. These variations further increase the adaptability of plants towards the environment or surroundings.
Question. Explain the term “Regeneration” as used in relation to reproduction of organisms. Describe briefly how regeneration is carried out in multicellular organisms like Hydra.
Answer. Regeneration: It is the ability of an organism to give rise to a new organism/individual from their body parts.
Regeneration in Hydra:
(i) The body of Hydra by any means is cut into number of pieces.
(ii) Each piece contains specialized cells.
(iii) These cells, proliferate and make large number of cells.
(iv) From this mass of cells, different cells undergo changes to become various cell types and tissues, which finally develops into a new organism.
Question. Draw a diagram of the longitudinal section of a flower exhibiting germination of pollen on stigma and label.
(i) Ovary, (ii) Male germ-cell, (iii) Female-germ cell and (iv) ovule on it.
Four correct labelling, viz., ovary, male germ cell, female germ cell and ovule.
Question. State the changes that take place in the uterus when:
(i) Implantation of embryo has occurred.
(ii) Female gamete/egg is not fertilised.
Answer. (i) When implantation has occurred in uterus of mother, the inner lining of the uterus thickens and is richly supplied with the blood vessels to provide nourishment to the growing embryo.
(ii) If the egg is not fertilised, it lives for one day. Since, the thickened uterus lining is no more required; it slowly breaks down and comes out of the vagina as blood and mucous, known as menstruation, which lasts for about two to eight days.
Question. In the context of reproduction of species, state the main difference between fission and fragmentation. Also, give one example of each.
Answer. Fission: It is defined as the splitting of a unicellular organism into two or more than two separate daughter cells. It is the most common and simplest method of asexual reproduction in unicellular organisms, such as bacteria and Protozoa. Generally it is of two types i.e., binary and multiple fission. In binary fission, parent organism divides into two identical daughter organism with definite orientation. In multiple fission, parent organism divides into many identical daughter organisms. The nucleus of the cell splits repeatedly to form many smaller nuclei called daughter nuclei surrounded by a little bit of cytoplasm and thin membrane around them.
Fragmentation: It is a form of asexual reproduction in which multicellular organisms like filamentous algae (Spirogyra) breaks up into two or more small fragments or pieces. On maturity, each of which subsequently grows to form a complete new organism.
Question. (a) List in tabular form two differences between binary fission and multiple fission.
(b) What happens when a mature Spirogyra filament attains considerable length?
Answer. (a) Difference between binary fission and multiple fission:
(b) Spirogyra reproduces asexually by fragmentation. In this, the body breaks up into two or more small pieces of fragments upon maturation. These fragments grow into new Spirogyra.
Question. In a germinating seed, which parts are known as future shoot and future root? Mention the function of cotyledon.
Answer. Future shoot–Plumule
Function of cotyledon–It stores food for the
future plant or embryo.
Question. (a) Mention the role of the following organs of human male reproductive system:
(i) Testis; (ii) Scrotum; (iii) Vas deferens; (iv) Prostate glands.
(b) What are the two roles of testosterone?
Answer. (a) (i) Testis: To produce male gametes / sperm or male hormone / testosterone.
(ii) Scrotum: To provide optimal temperature to testis for the formation of sperms.
(iii) Vas deferens: To deliver the sperms to the urinary bladder.
(iv) Prostrate glands: To secrete the fluid which provides nutrition and medium for transport of sperms.
(b) (i) Regulates formation of sperms, (ii) Brings about the changes in boys during adolescence.
Question. Mention the total number of chromosomes along with the sex chromosomes that are present in a human female and a human male. Explain how in sexually producing organisms the number of chromosomes in the progeny remains the same as that of the parents.
Answer. Total number of chromosomes is 46. In human male, two sex chromosomes i.e., X or Y are present, while in human female, both sex chromosomes are X.
During sexual reproduction, a female gamete or egg cell fuses with a male gamete or sperm cell which are haploid to form zygote. Zygote is diploid (2n) which contains 46 chromosomes, 23 chromosomes from mother and 23 from father. In this way, an equal genetic contribution of male and female parents is ensured in the progeny.
Question. List three techniques that have been developed to prevent pregnancy. Which one of these techniques is not meant for males? How does the use of these techniques have a direct impact on the health and prosperity of a family?
Answer. Three techniques that have been developed to prevent pregnancy are:
(i) Barrier method: Physical methods such as condom, diaphragm and cervical caps are used to prevent entry of sperms in females.
(ii) Chemical methods: Drugs such as oral pills and vaginal pills are used by females.
(iii) Surgical methods such as vasectomy in males and tubectomy in females.
Chemical methods are not meant for males.
The use of these techniques helps in controlling population explosion thus providing better living conditions.
It helps in keeping proper gap between siblings thus gives better health to mother as well as children.
Question. Distinguish between pollination and fertilisation. Mention the site and the product of fertilisation in a flower.
Answer. Pollination: Transfer of pollen grains from stamen/anther to stigma.
Fertilization: Fusion of male & female gamete (or germ cells)
Site of fertilisation: Ovary/ Ovule
Question. Name the parts A, B and C shown in the diagram and write their functions.
Answer. Part A is Stigma.
Function: It is the terminal part of carpel, which may be sticky and helps in receiving the pollen grains from the anther of stamen during pollination.
Part B is Pollen tube.
Function: The pollen tube grows out of the pollen grain through the style to reach the ovary. It carries male gametes into the embryo sac in ovule.
Part C is Female Germ Cell.
Function: It is a female gamete which fuses with male gamete to form a diploid cell known as zygote.
Question. Name the parts A, B and C shown in the following diagram and state one function of each.
Answer. A. Anther: It produces pollen grains.
B. Style: It provides the path through which the pollen tube grows and reaches the ovary.
C. Ovary: It contains ovules and each ovule has an egg cell/female gamete. It develops into fruit after fertilization.
Question. What is contraception? Name any two methods. How does the use of these methods have a direct effect on the health and prosperity of a family?
State any three points.
Answer. (i) Contraception: Any method which prevents conception/ pregnancy is called contraception.
(ii) Barrier Method, Chemical Method, Surgical Method.
(iii) Health of women (mother) is maintained, Parents can give more attention to their children/ family, More resources may be made available for improvement of standard of living. (or any other relevant point)
Long Answer Type Question
Question. Draw a longitudinal section of a flower and label the following parts:
(i) Part that produces pollen grain.
(ii) Part that transfers male gametes to the female gametes.
(iii) Part that is sticky to trap the pollen grain.
(iv) Part that develops into a fruit.
Answer. i) anther
ii) pollen tube
Question. What are the various methods of vegetative propagation? Discuss any one method with example.
Answer. The various types of vegetative propagation are
• Micro-propagation in vitro
• It is a method in which two parts of different plants are joined together in such a way that they unite and grow as one plant.
• The portion of the plant that is grafted onto another plant is known as the scion, and the plant on which grafting is performed is known as the stock.
• The stock and the scion are tied in such a way that the cambium of the scion and the stock come in contact with each other.
• The stock is so chosen that it possesses qualities like disease resistance, high water absorbing capacity, deep penetrating roots for a firm hold, etc. The scion is so chosen that it possesses qualities like high yield of pulp or seeds (as desired) from a single fruit, etc.
• For example, citrus-root stock is used for a variety of grafts like sweet orange, lime, grape, etc.
Question. What is sexual reproduction? Explain how this mode of reproduction give rise to more viable variations than asexual reproduction? How does this affect the evolution?
Answer. Sexual reproduction is a natural mode of reproduction which involves two individuals and gamete formation.
During sexual reproduction, at the time of gamete formation, meiotic cell division takes place. During meiosis, crossing over between fragments of homologous chromosomes occurs which brings about new gene combinations to be transferred to new generation. Crossing over is the fundamental cause of origin of variations in sexually reproducing organisms.
Whereas in asexual reproduction, chance variations can only occur when there is inaccurate copying of DNA as only one individual is involved. The variations caused by crossing over in sexually reproducing organisms are subjected to the selection process. Natural selection selects those variations which have more adaptive value and guide them towards evolution of new species. In this way, sexual reproduction gives rise to more viable variations for evolution.
Question. Different organisms reproduce by different methods suitable to their body designs.
(i) Justify the above statement using examples of three different organisms which reproduce by different methods of asexual reproduction.
(ii) Differentiate between sexual and asexual modes of reproduction.
Answer. (i) (a) Binary Fission in Amoeba: In this method, the nucleus first divides mitotically into two, followed by the division of the cytoplasm. The cell finally splits into two daughter cells. So, from one Amoeba parent, two daughter amoebae are formed.
(b) Budding in Hydra: In budding, a small part of the body of the parents grows out as a ‘bud’ which then detaches and becomes a new organism. Hydra reproduces by budding using the regenerative cells. A bud develops as an outgrowth in Hydra due to repeated cell division at one specific site. When fully mature, the bud detaches itself from the parent body and develops into new independent individuals.
(c) Regeneration in Planaria: In this method, small cut or broken parts of the organisms body grow or regenerate into separate individuals. Planaria can be cut into any number of pieces and each piece grows into a complete organism.
(ii) Differences between Sexual and Asexual Reproduction:
Question. Define pollination. Explain the different types of pollination. List two agents of pollination. How does suitable pollination lead to fertilization?
Answer. Pollination: Transfer of pollen from anther/stamen to stigma of the flower Types of Pollination:
(a) Self pollination: Transfer of pollen from anther/stamen to stigma occurs in the same flower.
(b) Cross pollination: Pollen is transferred from anther stamen of one flower to stigma of another flower.
Agents of pollination: Wind, Water, Insects and Animals
A tube grows out of the pollen grain and travels through the style, to reach the female germ cell in the ovary to cause fertilization
Question. (a) Write the functions of following parts in human female reproduction system:
(i) Ovary, (ii) Oviduct, (iii) Uterus
(b) Describe in brief the structure and function of placenta.
Answer. (a) (i) Ovary: Releases egg / female gamete/ovum, Releases oestrogen/female hormones.
(ii) Oviduct: Transportation of ovum/egg/ from ovary to the uterus/Site of fertilization.
(iii) Uterus: Development of embryo/foetus.
(b) Placenta: It is disc like tissue embedded in uterine wall which contains villi on the embryo side of the tissue and blood space on mother side.
Function of placenta: Provides nourishment to embryo from mother’s blood / Removal of waste from embryo to mother’s blood.
Question. (a) Draw a diagram showing germination of pollen on stigma of a flower and mark on it the following organs/parts:
(i) Pollen grain (ii) Pollen tube (iii) Stigma (iv) Female germ cell
(b) State the significance of pollen tube.
(c) Name the parts of flower that develop after fertilization into: (i) Seed (ii) Fruit.
(b) Pollen tube carries male gametes to ovule present inside the ovary leading to fertilization.
(c) After fertilization, ovary develops into fruit whereas ovules into the seed.
Question. (i) Describe the various steps involved in the process of binary fission with the help of a diagram.
(ii) Why do multicellular organisms use complex way of reproduction?
(ii) Multicellular organisms cannot reproduce by cell because they are not simple random collection of cells. In them, specialized cells are organized as tissues which are organized into organs Cell-bycell division would be impractical. Multicellular organisms, therefore, require to use more complex ways of reproduction.
Question. (a) Suggest any two categories of contraceptive methods to control the size of human population which is essential for the prosperity of a country.
Also explain about each method briefly.
(b) Name two bacterial and two viral infections each that can get sexually transmitted.
(c) List two advantages of using condom during sexual act.
Answer. (a) Methods of contraception:
(i) Barrier method or mechanical method/ Condom/Diaphragm, to prevent the meeting of sperms and ova.
(ii) Chemical method/ Oral pills: Changes the hormonal balance of the female partner so that the eggs are not released.
(iii) Surgical method: To block the vas deferens in males/ vasectomy or the fallopian tube (oviduct) in females/ tubectomy, to prevent the transfer of sperms or egg and hence no fertilization takes place.
(b) Bacterial infections: Syphilis and Gonorrhea Viral infections: Human papilloma virus (HPV), HIV
(c) (i) Prevents meeting of sperm and ova
(ii) Protects against sexually transmitted diseases
Question. (a) Name the organ that produces sperms as well as secretes a hormone in human males. Name the hormone it secretes and write its functions.
(b) Name the parts of the human female reproductive system where fertilisation occurs.
(c) Explain how the embryo gets nourishment inside the mother’s body.
Answer. (a) Testes
Functions of Testosterone:
(i) Formation of sperms
(ii) Development of secondary sexual characters
(b) Fallopian Tubes/Oviduct
(c) Placenta, a special disc-like tissue embedded in the mother’s uterine wall and is connected to the foetus/embryo.
Placenta provides a large surface area for glucose and oxygen/nutrients to pass from the mother’s blood to the developing embryo/foetus.
Question. (a) Draw a diagram to show spore formation in Rhizopus.
(b) With the help of an example differentiate between the process of Budding and Fragmentation.
(c) Why is vegetative propagation practiced for growing some type of plants?
Answer. (a) Spore formation in Rhizopus:
(b) Differences between Budding and Fermentation:
(c) Vegetative propagation is practiced for growing some type of plants because:
(i) Only one parent is required for reproduction; this eliminates the need of special mechanisms (pollination) and fusion of gametes i.e., fertilization.
(ii) Many plants are able to tide over unfavourable conditions because of the presence of vegetative reproductive parts like tubers, corns and bulbs.
(iii) Plants that do not produce seeds can be propagated by this method, e.g., sugarcane and potato.
(iv) Vegetative propagation is a cheaper, easier and rapid method of reproduction in plants than growing plants from seeds. For examplelilies grow very slowly and take up to seven years to develop flowers when their seeds are grown, but when grown vegetatively, flowers are produced only after a year or two.
(v) The trait (character) of the parent plant is preserved and the offsprings are genetically identical.
Question. (a) “Use of a condom is beneficial for both the sexes involved in a sexual act.” Justify this statement giving two reasons.
(b) How do oral contraceptive help in avoiding pregnancies?
(c) What is sex selective abortion? How does it affect a healthy society? (State any one consequence)
Answer. (a) (i) Prevents meeting of sperm and ova
(ii) Protects against sexually transmitted diseases
(b) Oral pills contain hormones which prevent the ovaries from releasing ovum into the oviduct.
(c) Selective abortion means abortion (termination) of pregnancy, especially female foeticide.
Effect: Society will have imbalance in the male female ratio.
Question. (a) Draw the diagram of female reproductive system and match and mark the part(s):
(i) Where block is created surgically to prevent fertilization.
(ii) Where CuT is inserted?
(iii) Inside which condom can be placed.
(b) Why do more and more people prefer to use condoms? What is the principle behind use of condoms?
Correct diagram with correct labelling, correctly matched with the following parts:
(i) Fallopian Tube/Oviduct
(b) People prefer use of condoms as it prevents STDs/gives privacy to the user. Condoms help create a mechanical barrier preventing meeting of sperms and ovum.
Question. Give one example each of unisexual and bisexual flowers. Differentiate between the two types of pollination that occur in flowers. What happens when a pollen lands on a suitable stigma? Write about the events that occur till the seed formation in the ovary.
Answer. Unisexual Flower: Papaya/Water-melon/ any other
Bisexual Flower: Hibiscus/Rose/ any other
Self pollination: The pollen grains are transferred from the anther to the stigma of the same flower or to the flower of the same plant.
Cross pollination: The pollen grains are transferred from the anther to the stigma of a flower of a different plant.
• After pollen lands on a suitable stigma, a pollen tube grows out of pollen grain and travels through the style to reach the ovary.
• The male germ cell fuses with the female germ cell to form a zygote.
• Zygote divides several times to form an embryo within the ovule.
• The ovule develops tough coat and gradually gets converted into a seed.
Question. What is vegetative propagation? List with brief explanation three advantages of practising this process for growing same types of plants. Select two plants from the following which are grown by this process:
Banana, Wheat, Mustard, Jasmine, Gram.
Answer. (a) Vegetative propagation is the development of a new plant from the vegetative parts / roots, stem and leaves of a plant.
(b) Advantages: (i) Such plants can bear flowers and fruits earlier than those produced from seeds.
(ii) Allows propagation of plants (banana, orange etc) that have lost capacity to produce seeds.
(iii) All plants produced are genetically similar to the parent plant and hence have all its characters.
Question. (a) What is pollination? Give its two types.
(b) Draw a longitudinal section of female reproductive part of a flower showing germination of pollen grain. Label on it the following:
(ii) Pollen tube with a male germ cell;
(iii) Female germ cell.
Answer. (a) Pollination: Process of transfer of pollen grains from the anther to the stigma of the flower.
Two types: Self-pollination and Cross pollination
Question. (i) Describe the role of prostate gland, seminal vesicle and testes in the human male reproductive system.
(ii) How is the surgical removal of unwanted pregnancies misused?
(iii) Explain the role of oral contraceptive pills in preventing conception.
Answer. (i) Prostate and the seminal vesicles produce fluid that nourishes the sperm. This fluid provides most of the volume of semen, the fluid in which the sperm is expelled during ejaculation. Testes secrete testosterone which brings about changes in the appearances in the boys at the time of puberty.
(ii) Female foeticides/illegal sex selected abortion of female foeticide.
(iii) Interfere in release of egg and eggs are not released.