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Q1. Name any three changes seen in human males and females which are indicative of reproductive maturity.

Solution

  Changes in males Changes in females 1. Testes mature and start producing sperms   1. Ovaries mature and start producing ovum; menstrual cycle begins   2. Pectoral girdle (shoulder girdle) grows   2. Pelvic girdle (hip girdle) becomes broad   3. Development of moustache and beard   3. Enlargement of breasts  

Q2. Merozoites are formed by the process of

• 1) Sporogony
• 2) Binary fission
• 3) Sporulation
• 4) Schizogony

Solution

In Plasmodium, when multiple fission takes place in the active adult form (schizont), the process is called schizogony. The daughter cells thus formed are called merozoites.

Q3. In grafting, the point where the stock and scion are joined is sealed off with wax and clay to

• 1) Hasten the process of grafting
• 2) Prevent the entry of pathogens and prevent the loss of water
• 3) Hold the two in place firmly till they are joined naturally
• 4) Make the joint permanent

Solution

In grafting, the point where the stock and scion are joined is sealed off with wax and clay to prevent the entry of pathogens and prevent the loss of water due to evaporation. 

Q4. Vegetative propagation in mint occurs by

• 1) Rhizome
• 2) Offset
• 3) Runner
• 4) Sucker

Solution

Vegetative propagation in mint occurs through suckers. Vegetative reproduction is a type of asexual reproduction for plants; it is a process by which new plants arise from the vegetative parts without the production of seeds or spores.  Propagation through offsets occurs in Pistia. Propagation through rhizomes occurs in Typha, Canna, ginger, turmeric and lotus. Propagation through runners occurs in Cynodon, Oxalis and Centella.

Q5. The process of release of the egg from the ovary is called

• 1) Insemination
• 2) Ovulation
• 3) Reproduction
• 4) Menstruation

Solution

Reproduction is the ability of the organism to produce a copy like itself. Menstruation is the periodic discharge of blood and mucosal tissue from the uterus and vagina. Insemination is the deliberate introduction of sperm into a female animal or plant for impregnating or fertilising the female for sexual reproduction.

Q6. As compared to a normal adult male, the basal metabolic rate of a normal adult female is

• 1) Same
• 2) Lower
• 3) Higher
• 4) Almost the same

Solution

The basal metabolic rate of a normal adult male is about 1600 Kcal/day, whereas that of a normal adult female is 1520 Kcal/day.

Q7. In certain plants, flowering is regulated by

• 1) Age of the plant
• 2) Moisture
• 3) Fertilisers
• 4) Duration of day and night

Solution

Flowering in plants is regulated by the length of the light phase (day) and the length of the dark periods (night).

Q8. A scion is grafted to a stock. The quality of fruits produced will be determined by the quality of

• 1) Scion
• 2) Both stock and scion
• 3) Stock
• 4) External environmental factors

Solution

The scion is derived from a plant possessing better characters. Therefore, the quality of fruits produced will be determined by the quality of the scion. For example, a scion of Dussehri mango is grafted on the stock of a Desi mango.

Q9. Menstrual cycle is completed in

• 1) 30 days
• 2) 31 days
• 3) 28 days
• 4) 27 days

Solution

It takes 28 days for the completion of one complete menstrual cycle.

Q10. In which of the following organisms is self-fertilisation observed?

• 1) Liver fluke
• 2) Flatworm
• 3) Earthworm
• 4) Fish

Solution

Self-fertilisation requires only one organism. It occurs in liver fluke. Cross-fertilisation occurs in fish, earthworm and flatworm.

Q11. Eichhornia is also known as

• 1) Lily
• 2) Water hyacinth
• 3) Lotus
• 4) Banana

Solution

Water hyacinth belongs to the genus Eichhornia.

Q12. The product of sexual reproduction generally generates

• 1) Large biomass
• 2) Prolonged dormancy
• 3) New genetic combination leading to variation
• 4) Longer viability of seeds

Solution

Sexual reproduction involves mixing of parental genetic material. This results in new genetic combination leading to variation which contributes to evolution of species.

Q13. In grafting, the portion to be grafted on the main plant is called

• 1) Scion
• 2) Adventitious bud
• 3) Stem
• 4) Stock

Solution

Adventitious buds are subnormal buds found at points along the stem. The stem is the trunk portion of the plant. The stock is the rooted supporting portion of one plant which is used for grafting.

Q14. Strobilanthes kunthiana bears flowers every _____ years.

• 1) 1
• 2) 10
• 3) 0.5
• 4) 12

Solution

Strobilanthes kunthiana bears flowers once every 12 years between September and October.

Q15. What is menstrual cycle?

Solution

A series of cyclic changes occurring in the ovaries of the female genital tract every month constitute the menstrual cycle.

Q16. Layering is of two types—air layering and mound layering. Of the two, Bougainvillea is grown by which method?

• 1) Both air and mound layering
• 2) Air layering
• 3) Bougainvillea cannot grow by layering
• 4) Mound layering

Solution

Bougainvillea is vegetatively grown by the process of air layering.

Q17. Mention the site where syngamy occurs in amphibians and reptiles.

Solution

In amphibians, syngamy occurs in water outside the body of the organism (external fertilisation and external development). In reptiles, syngamy occurs inside the body of the female (internal fertilisation and external development).

Q18. Regeneration of a plant cell to give rise to a new plant is called

• 1) Totipotency
• 2) Reproduction
• 3) Budding
• 4) Pluripotency

Solution

Reproduction is the ability of living organisms to make a copy like itself. Budding involves the formation of a daughter individual from a small projection called bud arising on the parent plant. Pluripotency is the potential of a cell to develop into more than one type of mature cell depending on the environment.

Q19. What is vegetative propagation? Give two examples.

Solution

Vegetative propagation involves the production of new individuals from vegetative plant propagules such as buds, tubers and rhizomes. Examples: (1) Potato tubers possess buds which grow into new plants. (2) Adventitious buds of Bryophyllum leaves grow to form new plants.

Q20. Which is a better mode of reproduction, sexual or asexual? Why?

Solution

Sexual reproduction is a better mode of reproduction as compared to asexual reproduction because it involves meiosis and the fusion of male and female gametes. Such a fusion involving two parents results in offspring which are not identical to the parents. It also causes variation which is essential for evolution and survival of the species under diverse changes in environmental factors.

Q21. Define: (i) Juvenile phase (ii) Reproductive phase (iii) Senescent phase

Solution

(i) Juvenile phase is the period of growth between the birth of an individual up to maturity. (ii) Reproductive phase starts after the juvenile phase and remains up to the stage when an organism is capable of reproduction. (iii) Senescent phase is the phase of ageing when an organism loses its capacity of reproduction. In plants, it is characterised by yellowing and leaf fall.

Q22. Which of the following is monoecious?

• 1) Marchantia
• 2) Cockroach
• 3) Date palm
• 4) Chara

Solution

Chara is monoecious as the male and female sex organs develop on the same plant body, while the rest are dioecious.

Q23. Embryo sac is found in

• 1) Endosperm
• 2) Ovule
• 3) Embryo
• 4) Seed

Solution

The embryo sac is a structure within a plant ovule which contains the egg cell. It develops from the megaspore and contains the embryo plant and endosperm after fertilisation.

Q24. State one difference between oviparous and viviparous animals.

Solution

Oviparous animals lay eggs (e.g. birds), while viviparous animals give birth to their young ones (e.g. humans, cats, dogs). 

Q25. Discuss the significance of vegetative propagation.

Solution

The significance of vegetative propagation is as follows: 1. Characters of the parent plant are preserved. A good variety produced can be propagated by vegetative means. 2. It is a quicker method. 3. It is an easier and cheaper method of propagation. 4. It is the only method of reproduction and perpetuation in plants which does not produce viable seeds. 5. It is easier to get rid of pathogen from any part of the plants by vegetative propagation. 6. Flowers produced on the scion are much superior in quality. 7. It is a less expensive method of multiplying plants. 

Q26. What are gemmules? State their functions.

Solution

Gemmules are internal buds formed inside freshwater sponges, e.g. Spongilla. These are formed during unfavourable conditions and help in perennation and dispersal. 

Q27. A special type of fleshy bud which develops in aquatic plants for vegetative propagation is

• 1) Turion
• 2) Stolon
• 3) Bulbil
• 4) Offset

Solution

Turions are a special type of fleshy buds which develops in aquatic plants for vegetative propagation.

Q28. Parthenogenesis can be observed in

• 1) Aphid
• 2) Earthworm
• 3) Tapeworm
• 4) Taenia

Solution

Parthenogenesis is a modified form of sexual reproduction in which the egg develops into a complete organism without fertilisation. It is observed in bees, rotifers, aphids and crustaceans.

Q29. Rearrange the following events of sexual reproduction in the sequence in which they occur in a flowering plant: Embryogenesis, Fertilisation, Gametogenesis, Pollination

Solution

Events of sexual reproduction in a flowering plant: Pollination, Gametogenesis, Fertilisation, Embryogenesis

Q30. Vegetative propagation in Pistia occurs by

• 1) Offset
• 2) Stolon
• 3) Sucker
• 4) Runner

Solution

Propagation through stolons occurs in Fragaria and Vallisneria. Propagation through suckers occurs in Mint and Chrysanthemum. Propagation through runners occurs in Cynodon, Oxalis and Centella.

Q31. Distinguish between binary fission and multiple fission.

Solution

Binary fission and multiple fission   Binary fission Multiple fission 1. Forms two daughter individuals 1. Forms many daughter individuals 2. Divides only once 2. Divides repeatedly 3. No residue is left 3. Residue is left 4. Takes place in favourable conditions 4. Takes place in favourable as well as unfavourable conditions 5. Immortality is present 5. Immortality is absent Example: Amoeba reproduces by binary fission Example: Plasmodium reproduces through multiple fission  

Q32. Why is vegetative reproduction practised for growing some types of plants?  

Solution

Vegetative reproduction is practised for growing some types of plants because (i) Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds. (ii) Vegetative propagation is also applied to plants such as banana, orange, rose and jasmine which have lost the capacity to produce seeds. (iii) All plants produced by vegetative propagation are genetically similar to the parent plant. 

Q33. Why is banana considered a good example of parthenocarpy?

Solution

Banana is called a parthenocarpic fruit because it develops without fertilisation and is thus seedless. 

Q34. Most sugarcane varieties cultivated today are aneuploids and are sterile. However, they grow and perform extremely well and sterility is not of any disadvantage. Why? 

Solution

Sugarcane reproduces vegetatively from the nodal segments. Therefore, although they are aneuploids and sterile, they perform extremely well. 

Q35. What are vegetative propagules? Give two examples.

Solution

In plants, the units or structures of vegetative propagation which are capable of giving rise to new offspring are called vegetative propagules. Examples: Runner, rhizome, sucker, tuber, offset and bulb

Q36. Mention the advantages of artificial vegetative propagation.

Solution

Advantages of artificial vegetative propagation: 1. Allows quick production of new plants 2. Allows combination of good qualities of two different varieties 3. Provides an excellent method for propagating desirable varieties of plants economically with less attention and in comparatively shorter time 

Q37. What is the basic difference between binary fission and budding?

Solution

In case of binary fission, the unicellular organism divides by cell division to give rise to two equal and similar offspring. In case of budding, the organism produces a small bud which gradually grows in size and then separates from the parent.

Q38. Why is reproduction essential for organisms?

Solution

Reproduction is essential for organisms because it enables the continuity of the species generation after generation.

Q39. Distinguish between asexual and sexual reproduction.

Solution

Asexual and sexual reproduction Asexual reproduction Sexual reproduction 1. Involves the participation of a single individual parent. 1. Involves the participation of two separate parents. 2. Occurs without the formation of gametes. 2. Requires the formation of gametes. 3. Does not involve meiosis or reduction division. 3. Involves meiosis or reduction division. 4. Does not involve sexual fusion or fusion of gametes. Zygote is not formed. 4. Requires fertilisation to take place between two opposite gametes leading to the production of a zygote.  5. Offspring produced are genetically similar to the parents. They do not show variations. 5. Offspring produced exhibit genetic variation and are different from either of the two parents. 6. Very quick method of multiplication of individuals. 6. Very slow method of multiplication of individuals.  

Q40. Describe the post-fertilisation changes in a flower.

Solution

After fertilisation, the sepals, petals and stamens wither and fall off. In some cases, the sepals remain persistent. The ovules are transformed into seeds, the zygote becomes an embryo and the ovary becomes a fruit.