NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants
NCERT solutions for class 7 science chapter 12 reproduction in plants: Solved Exercise Questions:
Q1. 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 _____________.
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 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 fertilization .
(e) Seed dispersal takes place by means of wind , water, and animal .
Q2. Describe the different methods of asexual reproduction. Give examples.
Answer:
Different methods of asexual reproduction are:
(i) Fission : is division, the parent cell divides into two or more cells. Fission can be of two types, namely, binary fission and multiple fission. In binary fission, the parent cell divides into two equal halves called daughter cells. During the multiple fission, the organism divides itself into numerous daughter cells.
(ii) Fragmentation : The parent body divides into two or more fragments. Later, each fragment develops into a new individual.
(iii) Regeneration : In these organisms, when the cell divides into numerous pieces, each piece proliferates and differentiates to regenerate new organisms. For example, when a lizard loses its tail, it grows a new one.
(iv) Budding : Some organisms develop buds on their body and these buds develop into a new individual, this is known as budding.
(v) Vegetative propagation : Reproduction through their vegetative parts such as leaves, roots, buds, and stems and this is known as vegetative propagation.
Q3. Explain what you understand by sexual reproduction.
Answer:
When two parents are involved in reproduction, the method is called sexual reproduction.
During fertilization, the male and female gametes fuse to produce a zygote.
Then zygote subsequently develops into an embryo which further develops into a new individual.
Q4. State the main difference between asexual and sexual reproduction.
Answer:
The main differences between asexual and sexual reproduction are:
|
S.No. |
Asexual reproduction |
Sexual reproduction |
|
1. |
Only one parent is involved. |
Two parents are required i.e., male and female |
|
2. |
The offspring formed is similar to the parent. |
The offspring formed shows some variation with respect to the parent. |
|
3. |
For example, hydra, yeast, etc. show asexual reproduction. |
For example, humans, animals, insects, etc. shows sexual reproduction. |
Q5. Sketch the reproductive parts of a flower.
Answer:
The sketch of the reproductive parts fo flower is shown below:
Q6. Explain the difference between self-pollination and cross-pollination.
Answer:
The differences between the self-pollination and the cross-pollination are:
|
S.No. |
Self-pollination |
Cross-pollination |
|
1. |
Within the same flower, the pollen grains are transferred to the stigma. |
The pollen grains are transferred to the stigma of a different flower. |
|
2. |
Pollinating agents are not required in this type of pollination. |
Pollinating agents such as the winds, water, insects, etc. are required in this type of pollination. |
|
3. |
For example, sunflower, peanuts, etc. |
For example, rose, mango, etc, and most of the flowering plants. |
Q7. How does the process of fertilisation take place in flowers?
Answer:
Once the pollen grains spread on the stigma, it produces a pollen tube and this process is called the germination of pollen grains.
Then the pollen tube penetrates the style and reaches the ovary where the male nucleus is transferred through this pollen tube and finally, the fusion of male and female nuclei takes place inside the ovary. Thus, this step is called fertilization.
Q8. Describe the various ways by which seeds are dispersed.
Answer:
Seeds and fruits of plants are carried away by the wind, water, and animals.
By wind: 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 far away places.
By water: Some seeds are dispersed by water. These fruits or seeds usually develop floating ability in the form of the spongy or fibrous outer coat as in coconut.
By animals: Some seeds are dispersed by animals, especially spiny seeds with hooks that get attached to the bodies of animals and are carried to distant places. Examples are Xanthium and Urena.
By bursting: 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.
Q9. Match items in Column I with those in Column II:
Column I Column II
(a) Bud (i) Maple
(b) Eyes (ii) Spirogyra
(c) Fragmentation (iii) Yeast
(d) Wings (iv) Bread mould
(e) Spores (v) Potato
(vi) Rose
Answer:
The matched columns are shown below:
|
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 |
Q10. Tick the correct answer: (a) The reproductive part of a plant is the
(i) leaf (ii) stem (iii) root (iv) flower
Answer:
(a) The reproductive part of a plant is the
(iv) Flower.
Q11. Tick the correct answer: (b) The process of fusion of the male and the female gametes is called
(i) fertilisation (ii) pollination (iii) reproduction (iv) seed formation
Answer:
(b) The process of fusion of the male and the female gametes is called (i) Fertilization.
Q12. Tick the correct answer:
(c) Mature ovary forms the
(i) seed (ii) stamen (iii) pistil (iv) fruit
Answer:
(c) Mature ovary forms the (iv) Fruit.
Q13. Tick the correct answer:
(d) A spore producing organism is
(i) rose (ii) bread mould (iii) potato (iv) ginger
Answer:
(d) A spore producing organism is (ii) bread mould.
Q14. Tick the correct answer:
(e) Bryophyllum can reproduce by its
(i) stem (ii) leaves (iii) roots (iv) flower
Answer:
(e) Bryophyllum can reproduce by its (ii) leaves.