19 Reproduction in Plants

NIOS Biology Intext Solutions Chapter 19

INTEXT QUESTIONS 19.1

1. Define reproduction.

Ans: The process by which living organisms produce their offspring for the continuity of the species.

2. How is asexual reproduction different from sexual reproduction?

Ans: When offspring are produced from vegetative parts of a parent without the fusion of gametes, it is called asexual reproduction. When the fusion of male and female reproductive cells occurs in male and female reproductive organs, it is called sexual reproduction.

3. What is a gamete?

Ans: The male and female reproductive cells are known as gametes.

4. Name two types of vegetative reproduction.

Ans: Fission, budding, fragmentation.

5. Choose the correct option

Apomixis is:

(a) Development of plants in darkness

(b) Development of plants without fusion of gametes

(d) Effect of low temperature on plant growth

Ans: (b) Development of plants without fusion of gametes

INTEXT QUESTIONS 19.2

l. Define the term isogamy. Which species of Chlamydomonas exhibits isogamy?

Ans: When the male and female gametes are morphologically identical but differ physiologically, their fusion is called isogamy. Chlamydomonas eugametos and C. eherenburgii exhibit isogamy.

2. Where does meiosis occur in Chlamydomonas?

Ans: Meiosis in Chlamydomonas occurs in the zygote.

3. Give the method of asexual reproduction in Chlamydomonas. What is the function of zoospores in Chlamydomonas?

Ans: Zoospores are the mode of asexual reproduction in Chlamydomonas. They produce zoospores when water is available in plenty. These zoospores develop a cell wall and will grow into an adult cell.

4. Name the species of Chlamydomonas that reproduces by anisogamy and the species that reproduces by oogamy.

Ans: Anisogamy – C. braunii; Oogamy – C.oogamum and C. coccifera

5. Define the terms zoospore and aplanospore.

Ans: A flagellate, thin-walled, asexual reproductive unit is called a zoospore. If a zoospore loses flagella and becomes non-motile, it is called aplanospore.

INTEXT QUESTIONS 19.3

1. Vegetative reproduction in Spirogyra takes place by means of _________.

Ans: Fragmentation

2. Name the kind of sexual reproduction that occurs in Spirogyra.

Ans: Scalariform conjugation.

3. When does meiosis occur in Spirogyra?

Ans: In Spirogyra, the diploid nucleus in the zygote undergoes meiosis when the conditions are favourable.

4. How many filaments are involved in lateral conjugation?

Ans: Only one filament is involved in lateral conjugation, where the male and female cells are arranged in alternate pairs.

INTEXT QUESTIONS 19.4

1. Define the terms (i) Annual (ii) Biennial (iii) Perennial

Ans:

Annual – Plants that produce flowers and seeds and die within one season.
Biennial – Plants which complete their life cycle in two seasons. In the first season, they are in a vegetative state, and in the second season, they reproduce and eventually die.
Perennial – Plants that live for several years are perennials. For the first few years, they are in a vegetative state, and later, they flower and produce fruits and seeds every year.

2. List the factors that induce flowering

Ans: Temperature, light, and day length

3. Give one example where external application of hormone can reverse the sex of a flower

Ans: Cannabis or Cucumis

4. Name the essential whorls in a flower.

Ans: Stamens and carpels.

INTEXT QUESTIONS 19.5

1. What is the innermost wall layer of microsporangium called?

Ans: Tapetum.

2. Name the organ where pollen grains are formed.

Ans: Pollen sac.

3. Name the two layers of pollen grain.

Ans: Exine and intine.

4. Name two parts of a mature ovule.

Ans: Nucellus and integuments

INTEXT QUESTIONS 19.6

1. What is pollination?

Ans: Pollination is the transfer of pollen grains from the anther to the stigma of a flower.

2. Mention suitable terms for the following :

(i) Flowers do not open and are self-pollinated.

(ii) Male and female reproductive organs mature at different times.

Ans:

(i) Cleistogamy

(ii) Dichogamy

3. Give two features of insect-pollinated flowers :

Ans:

(i) Flowers are large, coloured, and showy.

(ii) Some flowers secrete nectar.

INTEXT QUESTIONS 19.7

1. Which part of the ovule forms the seed coat?

Ans: Integuments.

2. Define a seed.

Ans: A seed is a ripened ovule that contains the embryo.

3. Give one example of a dicot seed and one of a monocot seed.

Ans: Dicot seed: Pea or Gram

Monocot seed: Maize grain.

4. Define a fruit.

Ans: A fruit is a ripened ovary that protects the seed inside.

5. List the parts of a mature seed.

Ans: Embryo

Endosperm

Cotyledons

6. Development of an embryo from a cell of an embryo sac other than the egg is an example of ________?

Ans: Adventive Polyembryony

7. Formation of more than one embryo from a single zygote is called ______

Ans: Cleavage Polyembryony

INTEXT QUESTIONS 19.8

1. Define vegetative reproduction.

Ans: Vegetative reproduction is the formation of new plantlets from vegetative (somatic) parts of the plant, such as cells, buds, leaves, stems, et,c where they are detached and develop into new plants.

2. Give an example of each of the following :

(a) rhizome

(b) tuber

(c) bulb

(d) runner

(e) sucker

Ans: (a) Ginger (b) Potato (c) Onion (d) Lawn grass (e) mint

3. Give an example of vegetative reproduction which is carried out by leaves.

Ans: Bryophyllum

4. Name two ways by which vegetative reproduction occurs in plants.

Ans: Rhizomes and Bulbs