NCERT Solutions Class 7 Science Chapter 12 Reproduction in Plants

NCERT Solutions for Class 7 Science for chapter 12 Reproduction in Plants

Question.1 Fill in the blanks:

(a) Production of new individuals from the vegetative part of parent is called ______.

(b) A flower may have either male or female reproductive parts. Such a flower is called ______.

(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as______.

(d) The fusion of male and female gametes is termed as _____.

(e) Seed dispersal takes place by means of______ ,______, and ______

Ans. 1

(a) Vegetative propagation

(b) Unisexual flower

(c) Self-pollination

(d) Fertilisation

(e) Wind, water and animals

Question.2 Describe the different methods of asexual reproduction. Give examples.

Ans.2 There are four different methods of asexual reproduction which are as follows:

1. Fragmentation- In this process, an organism, like algae, breaks down into two or more fragments and each fragment gives rise to a new individual. For example, Spirogyra undergo fragmentation as shown below:

2. Budding- In this process,a small bulb-like projection emerges from the mother cell that grows and develops into a new individual. Yeast undergoes budding to reproduce asexually that takes place in following manner:

3. Spore formation- Most of the fungi reproduce asexually by forming tiny spores which germinate to give rise to new individuals.

4. Vegetative propagation- It is seen in many plants in which vegetative plant parts give rise to new plant Like leaf of Bryophyllum and eyes of potato forms new plants as shown below:

 

Question.3 Explain what you understand by sexual reproduction.

Ans.3 Sexual reproduction is the process of producing offspring by an organism with involvement of male and female sexes. It involves fusion of male and female gametes that leads to the formation of zygote. The male and female gametes are produced by male and female flower parts, respectively. Male part of the plant is stamen that bears male gametes inside the pollens and female part of the plant is pistil that bears ovary containing female gamete or ovum. Pollens fall on stigma of the flower and germinate to form pollen tubes containing male gametes. Pollen tube enters the ovary releasing male gametes. One of the gametes fuses with ovum and undergo fertilisation to form zygote, completing the process of sexual reproduction.

 

Question.4 State the main difference between asexual and sexual reproduction.

Ans.4 In asexual reproduction, single parent gives rise to the offspring without producing seeds whereas, in sexual reproduction two parents of opposite sex participate to produce a seed from which a new individual emerges.

 

Question.5 Sketch the reproductive parts of a flower.

Ans.5 Various male and female reproductive parts of the flower can be sketched as follows:

Question.6 Explain the difference between self-pollination and cross-pollination.

Ans.6 In self-pollination, the pollens are deposited on the stigma of either the same flower or another flower on the same plant. In cross-pollination pollens are deposited from one flower to another flower of the same kind borne on another plant.

 

Question.7 How does the process of fertilisation take place in flowers?

Ans.7 The process of fertilisation takes place after pollination. Pollens on reaching the stigma of the flower germinate to form pollen tubes that carry male gametes. One of the male gametes fuses with female gamete on reaching ovary forming zygote.

 

Question.8 Describe the various ways by which seeds are dispersed.

Ans.8 Seed are carried by wind, water and animals for dispersal. Some seeds which are light and have wings or hairs are easily carried away by wind. 

Some other seeds develop thick fibrous coating to acquire floating ability and are dispersed by water. For example, coconut seed has fibrous seed coat 

Some other plants produce seeds with hook-like structures or spines with the help of which they get attached to the bodies of animals and disperse to larger distances. For example, seeds of Xanthium and Urena have hooks and spines.

 

Question.9 Match items in Column I with those in Column II:

Column I	Column II
Bud	Maple
Eyes	Spirogyra

 

Fragmentation	Yeast
Wings	Bread mould
Spores	Potato
	Rose

Ans.9 The correctly matched contents of Column I with

Column II are as follows:

Column I	Column II
Bud	Yeast
Eyes	Potato
Fragmentation	Spirogyra
Wings	Maple
Spores	Bread mould

 

Question.10 Mark the correct answer:

(a) The reproductive part of a plant is the

(i) leaf (ii) stem (iii) root (iv) flower

(b) The process of fusion of the male and the female gametes is called

(i) fertilisation  (ii) pollination  (iii) reproduction (iv) seed formation

(c) Mature ovary forms the

(i) seed  (ii) stamen (iii) pistil (v) fruit

(d) A spore producing plant is

(i) rose  (ii) bread mould  (iii) potato   (iv) ginger

(e) Bryophyllum can reproduce by its

(i) stem (ii) leaves (iii) roots (iv) flower

Ans. 10

(a) The reproductive part of a plant is the (iv) flower

(b) The process of fusion of the male and the female gametes is called (i) fertilisation

(c) Mature ovary forms the (vi) fruit

(d) A spore producing plant is (ii) bread mould

(e) Bryophyllum can reproduce by its (ii) leaves