REPRODUCTION REPRODUCTION

Transcription

1 INTORDUCTION Reproduction is one of the fundamental attributes of living organisms to produce young ones of their own kind. This process essential for survival of species on earth and thereby ensuring continuity of life. Reproduction in living organisms takes places by two general methods : asexual method involving only one organism and sexual method involving two different organisms, male and female. Population control measures have been developed to stop population explosion by using a number of techniques to prevent and control pregnancy. The normal reproductive health must be maintained by providing all relevant information to create awareness regarding family planning and sex related communicable diseases. IMPORTANT TERMS AND CONCEPTS 1. Reproduction. It is the process of producing new individuals of the same species by existing organisms of a species parents. 2. Significance of Reproduction. (i) It allows perpetuation of speies. (ii) It increases the population of species. (iii) It plays an important role in evolution by transmitting favorable variations from one generation to another generation. 3. Types of Reproduction. There are two main methods in which organisms give rise to new individuals Asexual reproduction and sexual reproduction. (i) Asexual reproduction. It is the process of producing new organisms from a single parent without the involvement of sex cells or gametes. Example: Binary fission in Amoeba, Budding in Hydra, Spore formation in Rhizopus fungus. Regeneration in Planaria, and Vegetative propagation in flowering plants like rose. (iii) Sexual reproduction. It is the process of producing new organism from two parents by making use of their sex cells or gametes. Examples: Humans, fish, frogs, cats, dogs, and most flowering plants. 4. Characteristics of Asexual reproduction. (i) Only one individual of an organism is involved, opposite sexes are not involved. (ii) Cell divisions are either amitotic or mitotic. (iii) The new individuals produced are genetically identical to their parents. (iv) Asexual reproduction presents a rapid mode of multiplication. 5. Advantages and disadvantages of Asexual reproduction: Advantages Asexual reproduction is simple and fast. Disadvantages (i) Evolutionary chance is not possible as no variations is produced. A species consequently cannot adapt to changes in its environment. (ii) Asexual reproduction produces identical organisms generation after generation. In case of any defect in the parent organism, the offspring also inherits it. 6. Methods of Asexual Reproduction. Asexual reproduction takes place by five different methods as follows: (i) Fission, (ii) Budding (iii) Spore formation (iv) Regeneration and (v) Vegetative propagation 7. Fission. This is the simplest method of asexual reproduction in unicellular forms of life such as Amoeba, Paramoecium and other protozoa.

2 In this process of fission, the parent organism splits or divides to form two or more new organisms. Fission is of two types : binary fission and multiple fission. (i) Binary Fission. It is the division of one cell into two similar or identical cells. In this method, the nucleus first divides amitotically into two, followed by the division of the cytoplasm. The cell finally splits into two daughter cells. In plants binary can be seen in bacteria, yeast and Euglena. Among animals, Amoeba and Paramoecium reproduce through binary fission. Fig, 12.1: Binary Fission in Amoeba (ii) Multiple Fission. In Multiple fission, many individuals are formed from a single individual. The nucleus of the cell divides repeatedly, producing many nuclei. Each nucleus is surrounded by a small amount of cytoplasm and many daughter cells are produced within the cyst. The cyst breaks up under favorable conditions and small offspring are liberated. In plants, multiple fission is seen in many algae and in animals, a common example of multiple fission is so that of the malarial parasite (Plasmodium). Fig. 12.2: Multiple Fission in Plasmodium 8. Budding. In budding a small part of the body of the parent organism grows out as a bud which then detaches and becomes a new organism. The nucleus of the parent divides and one of the daughter nuclei passes the bud. The bud detaches itself from the parent body and becomes a new individual after growing to full size. In plants, budding takes place in yeast and in animals budding is seen in Hydra and sponges. Fig. 12.3: Budding Hydra 9. Spore formation. In spore formation, the parent plant produces hundreds of tiny spore which can then produces new plants. During the growth of a fungus plants like Rhizopus, tiny round bulb-like structure called sporangium develops at the top of the hyphae. Graphics By:- Roshan Dhawan Written By:- P. K. Badhan

3 The nucleus divides several times within the sporangium and each part of the nucleus along with a bit of cytoplasm develops into a spore. When the sporangium of the plant bursts, then the spores are liberated, which develop into new hypha after reaching the ground. In non-flowering plants like fungi (Mucor, Rhizopus, Penicillium), bacteria, ferns or mosses, formation of spores is a common method of reproduction. Fig. 12.4: Spore formation in a Fungus (Rhizopus) 10. Regeneration. It is the ability of an organism to replace its lost body parts. A special case of regeneration is fragmentation, in which a parent multicelluar organism on maturing breaks up naturally to produce two or more daughter organisms. So, fragmentation is a method of asexual reproduction. Among plants, filamentous algae lie Spirogyra reproduce by this method. Hydra, Planaria and sponges exhibit regeneration. Fig. 12.5: Regeneration in Planaria 11. Vegetative propagation. In vegetative propagation, new plants are obtained from the parts of old plants like stems, roots and leaves, without the help of any reproductive organ. There are two vegetative propagation and (a) Natural vegetative propagation and (b) Artificial vegetative propagation 12. Natural vegetative propagation. Various structures that take part in this of reproduction are roots, stem and leaves. (i) Natural vegetative propagation by roots. In some plants like Dahlia, sweet potato, etc. the adventitious roots become thick swollen and tuberous due to storage of food. Adventitious buds are also present on them. When such roots bearing these buds are planted in the soil, new plants are produced as a result of vegetative propagation.

4 Swollen roots of plant Fig. 12.6: Natural Vegetative propagation by roots in Dahlia (ii) Natural vegetative propagation by stems. Some plants reproduce by means of stems. They may be aerial like runners, suckers of underground like ginger (rhizome), potato (tuber), onion (bulb). ] Fig. 12.7: Natural Vegetative propagating by stem in Potato (tuber) (iii) Natural vegetative propagation by leaves. The fleshy leaves of Bryophyllum bear adventitious buds in the notches along the leaf margin. When the leaves fall on the ground, the buds develop into small plants under favorable conditions. Then plantlets on being detached develop into independent plant. Fig. 12.8: Natural Vegetative propagation by leaves in Byyophyllum 13. Artificial vegetative propagation. Some plant growers have developed artificial methods of vegetative propagation like cutting, layering and grafting which are used in agriculture and horticulture. These methods of artificial vegetative propagation are traditional methods, which are gradually being replaced by modern methods involving tissue culture for commercial purposes. (i) Cutting. In this type of propagation any part of the plant root, stem or leaf is cut and buried partly in the moist soil.

5 Fig. 12.9: Cutting Method After sometimes, the cutting develops roots and grows into a new plant which is similar to the parent plant. Many plants like rose plant, Chrysanthemum, grapes are propagated by means of cutting. (ii) Layering. The adventitious roots are produced in the branch of the stem before the plant is detached the parent plant. The branch of stem is called a layer. This process is utilized in the propagation of plant and the phenomenon is called layering. Layering is used in the propagation of plants like Lemon, Guava, Hisbiscus, Bougainvillea, Jasmine, Raspberry, Strawberry and many ornamental plants. In some plants, one or more branches are bent close to the ground and covered with moist soil. After sometimes, the underground portion of these branches produce new adventitious roots and develops into a separate plant as in jasmine. Fig : Layering in Jasmine (iii) Grafting. In this method of reproduction two plants of closely related varieties are joined together so that they live as one plant. Fig : Different stages in Grafting The portion of a plant that is grafted on the other plant is called scion, and the plant in which grafting is performed is called the stock.

6 In a graft the cambium of both stock and scion are fused to form a connection between the two. By grafting a young scion can be made to flower when it is grafted on a mature tree. This method is applied to improve variety of fruits like mango, apple, peas, citrus and guava. 14. Tissue culture or Micropropagation. It is the production or propagation of new plants from isolated plant cells or small of plant tissue in a synthetic medium of culture solution. Tissue culture for producing new plants is done as follows: Some plant cells or tissues are taking from the tip of the plant and put into a suitable synthetic medium under sterile condition. The plant tissue develops to form a cellular mass called callus. The callus is transferred to another medium containing suitable plant hormone for growth and differentiation that forms plantlets. The plantlets produced are transplanted into pots or soil where they can grow to form mature plants. This technique is also known as micro propagation in vitro because it takes place outside the body of the parent plant in a test-tube using an artificial environment. Micro propagation technique is being used for the production of ornamental plants like Orchids, Dahlia and Carnation. 15. Advantages of vegetative propagation (i) Vegetative propagation is a cheaper, easier and more rapid method of propagation in plants than growing plants from their seeds. (ii) The traits or characters of the parent plant are preserved by vegetative propagation. (iii) Better quality of the plants can be maintained by this method. (iv) It results in propagation of those plants which do not produce viable seeds or produce seeds with prolonged period of dormancy. (v) The plants generated from vegetative means require less time to grow and have the advantage of being more uniform and genetically similar to the present stock. (vi) By this mode of reproduction, the plants skip the risky seeding stages, in which a number of plants die under adverse conditions. Many seedless varieties of grapes, banana and oranges are produced by this method. 16. Disadvantages of vegetative propagation (i) Vegetative propagation induces over crowding. (ii) There is not genetic variation, so there is less adaptability to the environment. (iii) The disease of his parent plant gets transferred to the offspring. (iv) The plants lose vigous. (v) New characters neither can be introduced nor can undesirable characters be eliminated. 17. Parthenogenesis. This is a process of development of an organism from and unfertilized egg. In animals, parthenogenesis is common in ants, beens and wasps. In plants, it has been observed in Chara, Sprrogyra, parthenogenesis is common in ants, bees and wasps. In plants, it has been observed in Chara, Spirogya, etc. 18. Sexual Reproduction and its Significance. Sexual reproduction is a type of reproduction is which the two sexes, namely, male and female are involved. The male sexual unit is known as male gamete or sperm while female sexual unit is termed as female gamete or ova. Thus, the two major processes, formation of gametes and fusion of gametes constitute sexual reproduction. The significance of sexual reproduction are as follows: (i) Sexual reproduction promotes diversity of characters in the offspring. (ii) It results in new combinations of genes brought together in the gamete and this reshuffling increases genetic variation. (iii) It plays a prominent role in the origin of new species. 19. Flow chart showing Asexual and sexual reproduction. Asexual Reproduction Organisms Sexual Reproduction

7 A A B Generation I Organism Produces Mate and produce B C Mate and B Produces Generation II Organism Produces E Mate and F Produces C (Hereditary characters and so on. Generation III remain the same from one (Hereditary characters vary organism G generation to the next) from one generation to the and so on. next). 20. Unisexual organism. In majority of animals like human beings, male and female sex organs are in different individuals, such organism which possess only one kind of reproductive organs a (male or female) in its body is called ad unisexual organism. 21. Bisexual organism or Hermaphrodite. In most flowering plants, and certain animals like tapeworm, earthworm, leeches, starfish; a single individual has both male and female sex organs in its body such organism is called bisexual organism or hermaphrodite. 22. Gametes. The cells involved in sexual reproduction are called gametes. The male gamete in animals are called sperm or spermatozoon and the female gamete in animals are called ovum or eggs. 23. Zygote. The cell shich is formed by the fusion of a male gamete and a female gamete is called zygote it is a fertilized ovum or fertilized egg. 24. Oospore. It is a diploid zygote formed by the fusion of male gamete with the egg cell. 25. Semen. It is a fluid containing secretions of accessory glands together with the sperms. Semen also contains enzymes that activate the sperm after ejaculation. 26. Embryo. It is the stage of development between the zygote or fertilized egg and the newly formed offspring. 27. Fertilisation. It is defined as the function of a male gamete (sperm) with a female gamete (an ovum or egg) to form a zygote during sexual reproduction. There are two different modes of fertilization in nature: The fertilization which occurs outsides the female body is called external fertilization in amphibians (like frogs and toads) and fishes. The fertilization which occurs inside the female body is called internal fertilization in mammals (including human beings), birds and reptiles. 28. Copulation or mating. It is the process by which spermatozoa from male testes are deposited in the body of a female where fertilization takes place during sexual reproduction. The structures associated with mating are called copulatory organs or accessory sex organs. 29. Schematic representation of the various steps involved in sexual reproduction.

8 30. Sexual reproduction in plants. Sexual reproduction is the most common method of reproduction in flowering plants. The sex or reproductive organs of a plant lie in its flowering. The function of a flower is to help in mating both male and female gamete, so that fertilization takes place to produce new seeds. The sexual reproduction in plants takes place in the following steps : The male organ of a flower called stamen makes the male gametes, which are present in pollen grains of the plant. The female organ of a flower called carpel or pistil makes the female gametes, which are present in ovules of the plant. The male gametes present in pollen grains fertilize the female gametes present in ovules. The fertilized ovules grow and become seeds. The seed produces new plants. 31. Parts of a flower. The flower are usually bisexual, male and female reproductive parts are present in the same plant. The flower is attached to the plant by a stalk or pedicel. The main parts of a flower are sepals, petals, stamens and carpels (pistil). Fig : Parts of a flower Sepals are usually green, leaf-like parts in the outermost circle of a flower. The function of sepals is to protect the flower in its initial stages when it is the form of a bud. Petals are the colorful parts of a flower whose base lies inside the sepals. The function of petals is to attract insects for pollination and to protect the reproductive organs, which are at the center of the flower. Stamen and carpels constitute the reproductive parts of a flower. Stamen is the male reproductive organ of the plant. A flower usually has a number of stamens in it. Each stamen is made up of two parts a filament, the stalk of stamen and an anther, the swollen top of stamen. Anther is the upper bilobed part and each lobe contains two pollen sacs within which numerous pollen grains are produced.

9 Fig : Male reproductive organ of a plant (Stamen) Carpel (Pistil) is the female reproductive organ of the plant. It is made up of three parts stigma, style and ovary. Stigma is the top part of carpel, which is for receiving the pollen grains from the anther of stamen during pollination. Style is the middle elongated part of the carpel which connects stigma to the ovary. Ovary is the swollen part at the base of a carpel, which contains ovules and each ovule has an egg-the female gamete. Carpel in a flower is surrounded by a number of stamens. Stigma Fig : Female reproductive organ of a plant (Carpel) 32. Formation of seeds. Seed is the reproductive unit of a plant. A new seed of the plant is formed when the male gamete present in a pollen grain unites with the female gamete present in the ovule. This takes place in two steps-pollination and fertilization. 33. Pollination. It is the transfer of pollen grains from the anther of a stamen of the stigma of a carpel. The pollen grains are transferred by many agents, such as insects (bees and butterflies), birds, man wind and water. Pollination is of two types-self pollination and cross pollination. 34. Self pollination. It is the transfer of pollen grains from the anther of a flower to the stigma of the same flower or another flower to produce nectar or scent or be colorful. Advantages: (i) Self pollination in bisexual flowers ensures continuity of the race. (ii) It helps to preserve the parental characters, as the gametes from the same flower are involved. (iii) It is not necessary for flowers to produce nectar or scent or be colorful. Disadvantages: (i) New varieties cannot be obtained by self pollination. (ii) The genetic defects of he breed cannot be removed. (iii) Repeated self pollination leads to loss of vigour and vitality of the species. 35. Cross Pollination. It is the transfer of pollen grains from the another of one flower to the stigma of another flower of a different plant of the same species. It is common in majority of flowering plants. Graphics By:- Roshan Dhawan Written By:- P. K. Badhan

10 Cross pollination occurs with the help of two main groups of agents-biotic such as insects, birds and man ; and abiotic such as wind and water. Advantages: (i) Cross pollination results in healthier offspring. (ii) Seeds produced by cross pollination have much better germinating capacity. (iii) More abundant and viable seeds are produced. (iv) Variations are introduced by cross pollination. Disadvantages: (i) Plants have to depend on external agencies for pollination. (ii) The pollen grains have to be produced in large quantity to ensure pollination. 36. Fertilization in plants. Pollination is followed by fertilization in plants. After reaching the stigma, the pollen grain develops the pollen tube. This pollen tube grows through the style and reaches the ovary where ovulus are located. The pollen tube enters the ovule through a small opening called micropyle, where it releases two male gametes into the embryo sac. One male gamete fuses with the egg contained in the embryo sac of the ovule; and this fusion of male and female gametes is called syngamy and its product is the zygote. The other male gamete fuses with the two polar nuclei and this process is called triple fusion, where three nuclei are involved in the fusion process, one male gamete and two polar nuclei. The process of double fertilization occurs inside each embryo sac, in which two fusions, syngamy and triple fusion take place. After fertilization, ovary develops into the fruit and ovules develop into the seeds. Fig : Fertilization in a flowering plant 37. Embryo sac. It is a large oval-shaped cell that develops in the ovule of flowering plants. 38. Sexual reproduction in Animals. The sexual reproduction in animals takes place in the following steps: Two different sexes (male and female) are required for the process. The male body produces male gametes or sperms from the testis, while the female body produces female gametes or ova from the ovary. The sperm enters into the ovum or egg, and fuses with it to form a new cell called zygote The process is called fertilization. So, the zygote is fertilized ovum or egg. The zygote then gets divided again and again to form a large number of cells and ultimately grows and develops into a new offspring. 39. Human Reproductive System is a complex system which develops and functions under the influence of hormones.

11 The reproductive organs of human beings testis in male and ovary in female becomes functional only after attaining sexual maturity. In males, sexual maturity is attained at the age of years, while in females at the age of years. This is known as the age of puberty. The testes and ovary produce viable gametes and also secrete hormones like testosterone (male hormone form testes) and estrogen and progesterone (female hormones from ovary). 40. Puberty. It is the age at which the sex hormones or gametes begin to be produced and the boy or girl becomes sexually mature. 41. Functions of Sex Hormones: (i) The sex hormones regulate the process of gametogensis. (ii) They maintain the structure and function of accessory sex organs. (iii) They develop secondary sex characters like facial, axial and public hair, pitch of the voice and development of mammary glands. 42. Male Reproduction system. The human male reproductive system consists of the following organs: Testes (singular testis) are the oval-shaped primary reproductive organs in man. A pair of testis lies in a small sac-like muscular structure outside the abdominal cavity called scrotum. The function of testis is to produce sperm and male sex hormone called testosterone. The sotum provides the optimal temperature for formation of sperms. Epididymis is called tube like structure firmly attached to the testis and serves as the storehouse of sperms. Inside the epididymis, a sperm become mature and develops motility. Vas deferens. The sperms are carried by a long tube called vas deferens or sperm duct into organs called seminal vesicles, where the sperms get nourished and stored. The seminal vesicle join to another tube coming from the urinary bladder. Urethra is a common duct for the passage of both urine and spermatic fluid. Urethra carries the sperms to an organ called penis which opens to the outside through a male pore. Penis forms the external male genital organ. It is cupulatory organ with thick muscular walls. The urethra passes through the entire length of the penis. It is used to pass urine, and for ejecting and depositing sperms in the female genital tract. Fig : Reproductive system of a Human Male 43. Female Reproductive System. The human female reproductive system consists of the following: Ovaries are a pair of small and oval shaped, located in the abdominal cavity near the kidney. Ovaries are the female primary reproductive organs which perform dual function of production of female gamete or ovum and the secretion of female sex hormones, estrogen and progesterone. Each ovary is composed of ovarian follicles and these follicles undergo maturation at puberty to produce ova. Fallopian tube or Oviduct is a pair of long convoluted tubes carries ova or eggs from the ovary to the uterus. The fallopian tube has a funnel shaped opening new the ovary. These tubes from other the sides open into a muscular structure, the uterus.

12 Uterus or womb is a hollow pear shaped organ within which the embryo develops. Its upper portion is broader, while its lower portion is narrower, called cervix. Vegina. The cervix opens into the vagina which is a tubular structure and also called birth canal. Vegina receives sperms from the male and also serves as the passage through which the fully developed foetus is born. Fig : Reproductive System of a Human Female 44. Sexual cycle in Females. The human reproductive cycle is concerned with the sexual cycle at a woman, which begins at the age of puberty. After this age, ovaries exhibit cycle of events at definite intervals. The ovarian follicles grow into mature follicles, and one follicle develops to form a mature ovum. The ovum is then released from the respective ovary by the process called ovulation. At the time of ovulation, fertilization can occur. After ovulation, the remaining part of the follicles secretes hormone progesterone which stimulates the thickening of the uterine wall. The breakdown and removal of the inner, thick and soft lining of the uterus along with the blood vessels in the form of vaginal bleeding is called menstrual flow or menstruation. The cycle of events taking place in the ovaries and uterus every twenty eight days and marked by the menstrual flow is called menstrual cycle or sexual cycle in human female. Menstruation occurs every 28 to 30 days and ovulation takes place in the mid of the menstrual cycle around 14th day. Both ovulation and menstruation stops temporarily when the women gets pregnant till birth of the offspring. The beginning of menstruation at puberty is called menarche. The age at which the menstruation stops and a woman lose her ability to bear children is called menopause. The period between menarche and menopause (i.e., from years to about years is the normal reproductive life of women. 45. Fertilization in human beings is internal. The male gamete (sperm) is introduced inside the female genital tract (vagina) by the process of copulation or mating. Sperms are highly active and mobile which move up through cervix into the uterus and then passes into the fallopian or tubes. In the fallopian tube only one sperm fertilizes the ovum to form a zygote. This is called fertilization. Fertilization occurs only if copulation takes place during the ovulatory period. The embryonic development of the zygote starts immediately in the thick inner lining of the uterus is called implantation.

13 Then, a special tissue develops between the uterine wall and the embryo (foetus) called placenta, where the exchange of nutrients, oxygen and waste products takes place. The time period from the development of foetus inside the uterus till birth is called gestation. The act of giving birth of the fully developed foetus at the end of gestation period is termed as parturition. The average duration of human pregnancy or gestation period is about 40 weeks or 280 days. 46. Population Control can be done by practicing birth control measures. A number of techniques have been developed to prevent and control pregnancy. These methods of control are categorized as: (i) Barrier methods. In this method, physical devices such as condoms, diaphragm and cervical caps are used. These devices prevent the entry of sperm in the female genital tract during copulation, thus acting as a barrier between them. (ii) Chemical Methods. In this method, specific drugs are used by females, which are of two types-oral pills and vaginal pills. Oral pills contain hormones which stop the ovaries from releasing ovum into the fallopian tube. These pills are also called oral contraceptives (OCs). The use of Intrauterine Contraceptive Devices (IUCDs) prevents implantation in the uterus. This device is a copper-t placed safely inside the uterus by a doctor or nurse. (iii) Surgical methods. In this method, a small portion of vas deferens in male and the fallopian tube in female is surgically removed or tied. It is called vasectomy in males and tubectomy in females. 47. Health is a state of complete physical, mental and social well being and not merely the absence of disease. 48. Reproduction health is all those aspects of general health which help a person to lend a normal, safe and satisfying reproduction life. It requires the awareness about human reproductive system, preventive and therapeutic methods to control sexually transmitted diseases, methods of birth control and the ability to manage disorders related to reproductive system. 49. Sexually Transmitted Diseases (STDs) are the diseases which are spread by sexual contact from an infected person to a healthy person. They are caused by various microorganisms that live in warm and moist environment of the vagina, urethra, anus and mouth. Some of the common sexually transmitted diseases are Gonorrhoea, Syphilis and Trichomoniasis which are all curable diseases. (i) Gonorrhoea. It is caused by bacterium Neisseria gonorrhoeae. It is characterized by inflammation of urinogenital in men and the cervix in women. (ii) Syphills. It is caused by bacterium Treponema pallidium. It is characterized by lesions in the mucous membrane of urinogenital tract and ulcers on genitalia. (iii) Trichomoniasis. It is caused by protozoan Trichomonas vaginalis. It is characterized by some vaginal discharge at the urinogential tract of the female. Another sexually transmitted disease is AIDS (Acquired Immune Deficiency Syndrome). It is caused by a virus called HIV (Human Immunodeficiency Virus). It is characterized by damaging the body s immune system, so that the body becomes weak and cannot protect itself against leading to death. 50. Primary Sex Organs. It refers to gonads which produce gametes as well as sex hormones. 51. Secondary Sex Organs. It refers to accessory organs like prostate and seminal vesicles in males and fallopian tubes and uterus in females. These do not produce gametes or hormones. 1 MARK QUESTIONS 1. Which one of the following is NOT a part of the organ-system to which the other three belong? (a) Seminiferous tubules (ii) Fallopian tube (c) Epididymis (iii) Vas Deferens 2. What harm is caused if the testis in human males fail to descend into the scrotal sacs? 3. List the general characteristics of the pollen grains of wind pollinated plants.

14 4. What is double fertilization? 5. Name any two hermaphrodite animals. 6. Why do tests in mammals descend into scrotum? 7. How are males and females produced in honey female? 8. Where does fertilization takes place in a human female? 9. Name the kind of reproduction in bees in which drones are produced. 10. Name the following: (i) The tubes which carry spermatozoa out from the testes. (ii) The two phases covering the first half and second half of menstrual cycle respectively. 2 MAKS QUESTIONS 1. Some crop plants can be grown from a seed as well as vegetatively from stem cutting. List any four advantages of vegetative propagation in such cases. 2. Show by a series of labeled sketches, the manner in which vegetative reproduction occurs in Hydra. 3. Draw a diagram to show the structure of a flower. 4. Name the different parts (in sequence) forming the duct system of human male reproductive system. What is the duct system for? 5. What is the significance of pollination? 6. Draw a diagram of longitudinal section of a pistil showing pollen germination and label the following parts: (i) Pollen tube, (ii) Embryo sac. OR Draw a diagram of longitudinal section of a pistil showing pollen germination and label the following parts: (i) Pollen tube, (ii) Embryo sac. 7. Explain the significance of the condition in humans in which the testes remain suspended in scrotum outside the abdominal cavity. 8. Leaves of Bryophyllum falled on the ground produce new plants whereas the leaves of rose do not. Why? 9. Mention any two functions of human ovary. 10. Define the term unisexual and bisexual giving one example of each. 11. Mention secondary sexual characters in human male and female. 12. Describe menstrual cycle. 13. Differentiate between menarche and menopause. 14. Write whether true (T) or false (F): (i) Fertilization is the fusion of sperm and ovum. (ii) Duration of menstrual cycle in human female is 20 days. (iii) Onset of menstruation is termed menopause. (iv) In human beings, male attains puberty little later than females. 15. Write the full name of VCD, AIDS, HIC, OC. 16. Define sexually transmitted disease and give two examples. 17. What are the functions of sex hormones? 18. Give the disadvantages of vegetative propagation in plants. 19. Enumerate the process of binary fission in four steps. 20. Show that spirogyra propagates by regeneration. 21. Describe the type of fission shown by Plasmodium. 22. What is the outcome of fertilization? What is fertilization otherwise known as? 23. What are the two possibilities of self-pollination? 24. Differentiate between the functioning of the human male and female reproductive system along with the follicular maturation. 25. Briefly explain the process of formation of the placenta.

15 26. Mention any two simultaneous changes that occur side by side in the female reproductive system along with the follicular maturation. 27. Name two STDs other than Syphilis and Gonorrhoea. How do they get communicated? 28. What are the advantages of tissue culture? 29. Bring out the differences between budding and fission? 30. Justify the statement Primary sex organs control the growth, function and maintenance of secondary sex organs. 31. Mention the functions performed by the secretions of the accessory/secondary sex glands in human males. 32. What are the functions of a flower? 33. Differentiate between ovum and zygote. 34. Differentiate between primary sex organ and secondary sex organ. 35. Differentiate between ovulation and menstruation. 36. Differentiate between stock and scion in grafting. 37. Why is cross-pollination considered to be superior than the self pollination? 38. Distinguish between male and female reproductive duct system in humans. 39. Give the basic features of asexual reproduction. 40. Give the basic features of sexual reproduction. 41. List two main advantages of sexual reproduction. 42. Why does sterility results if tests are retained in the abdomen? 43. Define menstruation. Why is menstrual cycle so called? 3 MARKS QUESTIONS 1. Draw a labeled diagram of the longitudinal section of a pistil showing pollen germination. 2. Give a labeled diagram of pistil showing in it the path of male gametophyte from the stigma to the embryo sac. 3. Discuss the significance of vegetative propagation. OR Give two advantages of vegetative propagation. 4. With the help of a flow chart explain the steps involved in asexual and sexual reproduction. 5. What causes joining up of stock and scion in grafting? Name one positive trait that the plant contributing scion should have and one positive trait that plant contributing the stock should have. 6. Show only by diagrams the stages of fission in paramecium. 7. How are spores formed in Rhizopus? 8. What is the significance of fertilization? 5 MARKS QUESTIONS 1. Trace the events that would take place in a flower the time the pollen grains of the same species fall on the stigma up to the completion of fertilization. Self Evaluation Test Time Allowed: 1 Hour Max. Marks: Give one example each of unisexual and bisexual organisms. 2. Name two sexually transmitted diseases caused due to bacteria.

16 3. What are the stamen and carpel in a flower? 4. How do insects help in cross pollination? 5. What are the male and female gonads in human beings? Mention their functions. 6. What are sexually transmitted diseases? Give one examples of sexually transmitted diseases. 7. Write a short note on micro propagation. 8. What is meant by vegetative reproduction? What are its advantages and disadvantages? 9. Distinguish between asexual and sexual reproduction. 10. Draw a labeled diagram to show the fertilization of an ovum by a sperm to form a zygote. 11. Describe the various steps involved in the sexual reproduction in animals.