NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants Exercise Questions

 

 

 

 

The process of fusion of male and female gametes (to form a zygote) is called fertilisation. The zygote develops into an embryo, and the embryo undergoes mitotic cell division to form seeds.

 

Seeds and fruits of plants are carried away by the wind, water and animals. Winged seeds such as those of drumstick and maple, light seeds of grasses or hairy seeds of aak (Madar) and hairy fruit of the sunflower get blown off with the wind to faraway places. Some seeds are dispersed by water. These fruits or seeds usually develop floating ability in the form of a spongy or fibrous outer coat as in coconut. Some seeds are dispersed by animals, especially spiny seeds with hooks which get attached to the bodies of animals and are carried to distant places. Examples are Xanthium and Urena. Some seeds are dispersed when the fruits burst with sudden jerks. The seeds are scattered far from the parent plant. This happens in the case of castor and balsam.

 

Sexual reproduction is a method where male and female gametes fuse to form a new individual. In plants, stamens and pistils are male and female reproductive organs which bear the anthers and ovary, respectively.

 

Different methods of asexual reproduction are as follows:

Vegetative Propagation

In this asexual reproduction, new plants are produced from roots, stems, leaves and buds of the individual plant.

Examples – Tuber of potato, the rhizome of ginger.

Budding

The bud is a small projection which gradually grows and gets detached from the parent cell and forms a new yeast cell. The new yeast cell grows, matures and produces more yeast cells.

Example – Yeast.

Fragmentation

In this mode of reproduction, the growth and multiplication are done by rapidly breaking down into two or more fragments. Each fragment grows into new individuals when water and nutrients are available.

Example – Algae

Spore Formation

This reproduction is done by spores which, under favourable conditions, germinate and develop into a new individual.

Examples – Fungi like Rhizopus, Mucor, etc.

Fission

It is a type of asexual reproduction where the unicellular organism splits to form new organisms.  There are two types of fission which are,

• Binary fission

• Multiple fission

Examples

Unicellular organisms that undergo binary fission are amoeba, paramecium, leishmania, etc.

Plasmodium undergoes the process of multiple fission.

 

 

 

 

 

 

 

a) (iv) flower

b) (i) fertilization

c) (iv) fruit

d) (ii) bread mould

e) (ii) leaves

 

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

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

(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 Pollination.

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

(e) Seed dispersal takes place by means of wind, water and animals.