Saturday, 30 April 2016

TEXTBOOK ANSWERS AND SOLUTIONS OF CBSE CLASS VII SCIENCE Chapter 12 Reproduction In Plants




1) Fill in the blanks:

ANSWER :- (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_ _.
(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 __.


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

ANSWER:- Different methods of asexual reproduction are:
1. Fragmentation: Parent body divides into distinct pieces which grow into new individuals. e.g. Spirogyra.
2. Budding: A small part of parent body grows out as a bud which detaches and becomes a new individual. Sometimes a chain of buds is also formed. e.g. yeast, corals, sponges etc.
3. Spores Formation: Parent plant releases thousands of tiny, spherical and unicellular spores which are protected by cell wall. When these spores find favourable environment, they grow into plants. e.g. mosses, ferns, moulds etc.
4. Regeneration: Many plants like cacti, potato, rose, sugarcane etc. reproduce by this method. New plants are produced from vegetative parts of the mother plant such as root, stem or leaves.

3) Explain what you understand by sexual reproduction.

ANSWER: - Sexual reproduction is a process which involves production of seeds. It requires two parents. Most plants reproduce sexually with the help of flowers. The main function of a flower is to reproduce and therefore develop new seeds that can grow into new plants.

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

ANSWER:-
ASEXUAL REPRODUCTION:-
i. Only one parent is needed.
ii.Offspring is genetically identical to its parent .
iii.Spirogyra, Yeast, moulds, potato exhibit asexual reproduction.

SEXUAL REPRODUCTION
i) Two parents or male and female gametes are required.
ii) Offspring exhibit variation with respect to its parents.
iii) Fruit bearing plants like mango, china rose reproduce sexually.

5) Sketch the reproductive parts of a flower.



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

ANSWER:-
Self-pollination:-
i) It involves the transfer of pollen from the stamen to the pistil of the same flower.
ii) It occurs only in bisexual flowers.

Cross-pollination:-
i) It involves the transfer of pollen from the stamen of one flower to the pistil of another flower of the same plant or that of a different plant of the same kind.
ii) It occurs in both unisexual and bisexual flowers.

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

ANSWER: - After pollination, pollen grains start growing into a pollen tube passing through pistil.
The tube reaches the ovule and enters it. The pollen tube carries the male gametes. The male gametes fuse with the ova (female gamete) and form a zygote. This process of fusion is called fertilization. Later zygote develops into an embryo. Meanwhile walls of the ovules develop into layers and form a seed. Thus a seed carries an embryo with stored food and is covered by a hard coating.

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

ANSWER: -

(a) Dispersal by animals − There are many ways by which birds and animals can disperse seeds. For example, birds and animals can eat the fruits and excrete the seeds away from the parent plant. Some seeds have barbs or other structures that get attached to the animal’s body and are carried to new sites. Some fruits have hooks on them which cling to fur or clothes.

(b) Dispersal by wind − Seeds that get dispersed by wind are usually smaller in size or they have wings or hair-like structures. For example, winged seeds of drumsticks, hairy fruit of sunflower, etc. are dispersed by wind.

(c) Dispersal by water − Many aquatic plants or plants that live near water has seeds that can float and are carried away by water. For example, coconuts can float and are disperse by water.

(d) Dispersal by explosion − Sometimes the seeds are dispersed by the bursting of fruits with sudden jerks. The seeds get scattered of distributed far from the parent plant. Examples of such plants are castor and balsam.

9)Match items in Column I with those in Column II

ANSWER:-
Column I                                 Column II
(a) Bud.                                   (iii) Yeast
(b) Eyes.                                  (v) Potato
(c) Fragmentation                    (ii) Spirogyra
(d) Wings                                (i) Maple
(e) Spores.                               (iv) Bread mould

10) Tick (√ ) 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 female gametes is called
(i) fertilisation
(ii) pollination
(iii) reproduction
(iv) seed formation
(c) Mature ovary forms the
(i) seed
(ii) stamen
(iii) pistil
(iv) 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

ANSWER:-    

a)(iv) flower
b)(i) fertilisation
c) fruit
d)(ii) bread mould

e)(ii) leaves
Written By Badal Paul
The author is a passionate blogger, writer and educationalist. This blog is created to ease troubles of the Cbse students. The author holds multiple blogs and the writer of the Novel KALCHAKRA, OOM AND THE CHOSEN FIVE.