Hello students and welcome to Chapter 8! These study materials include solutions to all exercise questions and extended learning activities, in-text questions, activities and a plethora of extra questions of many formats. Many of the solutions include attractive figures to further boost your understanding. We recommend that you study them in detail to extract maximum benefit.
Solutions to Exercise (Page No 90) of NCERT Class 7 Science Chapter 8 Reproduction in Plants:
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 _____________.
Answers:
(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.
2. Describe the different methods of asexual reproduction. Give examples.
Answer:
The different methods of asexual reproduction in plants are vegetative propagation, budding, fragmentation, spore formation etc.
(i) Vegetative Propagation: When new plants are produced from certain vegetative parts of the plant like roots, stems, leaves and budsthe type of reproduction is called vegetative propagation.
Example: Tuber of potato, rhizome of ginger, bulb of onion, leaf of Bryophyllum.
(ii) Budding: Reproduction happens via small bud-like projections in single-celled organisms like yeast. The bud gradually grows in size and gets detached from the parent to form a new single-celled organism.
Example: Yeast
(iii) Fragmentation: Organisms like algae reproduce by breaking up into multiple fragments which then grow into new organisms.
Example: Spirogyra (type of algae)
(iv) Spore Formation: Some plants reproduce by releasing spores which germinate and develop into a new individual under the right conditions.
Example: Fungi, moss, ferns
3. Explain what you understand by sexual reproduction.
Answer:
Sexual reproduction in plants happens in the flower using male reproductive part called stamen and the female reproductive part called pistil. The male gametes from the stamen fertilise the female gametes in the ovule to form a zygote. The zygote develops into an embryo from which new plants are born.
4. State the main difference between asexual and sexual reproduction.
Answer:
In asexual reproduction new plants are produced from vegetative parts of the parent plant and thus have one parent and have identical traits to that parent. However, in sexual reproduction new plants are produced by special male and female reproductive organs together and thus have two parents and inherit the traits of both parents.
Example of asexual reproduction – Tuber of potato.
Example of sexual reproduction – Apple tree.
5. Sketch the reproductive parts of a flower.
Answer:
The male reproductive part of the flower called stamen and the female reproductive part called pistil along with their different parts are shown below:
6. Explain the difference between self-pollination and cross-pollination.
Answer: The differences between self-pollination and cross-pollination are as follows:
| Self-pollination | Cross-pollination |
| (i) Self-pollination involves the transfer of pollen from the anther to the stigma of the same flower or another flower of the same plant. | (i) Cross-pollination involves the transfer of pollen from the anther of a flower to the stigma of a flower on a completely different plant. |
| (ii) Since reproduction due to pollination happens in the same plant the offspring bears similar traits to that single plant. | (ii) Since reproduction due to pollination happens in different plants the offspring bears traits which are a combination of the two plants. |
| (iii) It is less dependent on external pollinating agents such as wind, water, insects etc. | (iii) It is much more dependent on external pollinating agents such as wind, water, insects etc. |
| (iv) It is more reliable as it does not depend on external agents. | (iv) It is less reliable as it relies on external agents. |
| (v) Examples of self-pollinating plants are wheat, apricot trees etc. | (v) Examples of cross-pollinating plants are apple trees, grass etc. |
7. How does the process of fertilisation take place in flowers?
Answer:
The process of fertilisation occurs in the female reproductive part of the flower called the pistil and involves the fusion of male and female gametes inside the ovule to form the zygote.
(i) The pollen grains released by the male reproductive part (specifically the anther) carrying the male gamete land on the stigma of the female reproductive part called pistil in a process called pollination. This is shown in Figure (a).
(ii) On landing the pollen grain germinates and produces a pollen tube which grows downwards through the style and reaches the ovule. This is shown in Figure (b).
(iii) The male gamete inside the pollen is released which travels down the pollen tube and fuses with the female gamete or egg to form the zygote cell. This is also shown in Figure (b).
(iv) The zygote then develops into an embryo which ultimately grows into a new plant.
8. Describe the various ways by which seeds are dispersed.
Answer:
Seeds are dispersed by wind, water, animals and via ballistic dispersal when the fruit explodes releasing the seeds inside.
- Wind carries winged (e.g. drumstick, maple), light (grasses) and hairy (Aadar) seeds and hairy fruit of sunflower long distances.
- Water disperses fruits or seeds with spongy or fibrous outer coating (e.g. coconut) which can float.
- Animals disperse spiny seeds with hooks which get attached to their bodies (e.g. Xanthium, Urena). They also excrete seeds after eating fruit.
- In ballistic dispersal the fruits bursts with sudden jerks which scatters the seeds (e.g. Castor, Balsam).
9. 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 correct table is 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 |
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 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 (iv) fruit
(d) A spore-producing organism is
(i) rose (ii) bread mould
(iii) potato (iv) ginger
(e) Bryophyllum can reproduce by its
(i) stem (ii) leaves
(iii) roots (iv) flower
Answers:
(a) (iv) flower
(b) (i) fertilisation
(c) (iv) fruit
(d) (ii) bread mould
(e)(ii) leaves
Solutions to Extended Learning – Activities and Projects (Page No 91) of NCERT Class 7 Science Chapter 8 Reproduction in Plants:
1. Make your own cactus garden by collecting pieces cut from different kinds of cacti. Grow the variety in one single flat container or in separate pots.
Answer:
Solution to Extended Learning Problem 1
2. Visit a fruit market and collect as many local fruits as possible. If many fruits are not available, you can collect tomatoes and cucumbers (these are fruits although we use them as vegetables). Make drawings of the different fruits. Split the fruits and examine the seeds within. Look for any special characteristics in the fruits and their seeds.
You visit a library also to learn about this.
Answer:
Solution to Extended Learning Problem 2
3. Think of ten different fruit-bearing plants. Remember that many vegetables are also fruits of the plants. Discuss with your teacher, parents, farmers, fruit growers and agricultural experts (if available nearby) and find out the manner of their dispersal. Present your data in the form of a table as shown below:
| S. No | Name of fruit-bearing plant | Agent through which seeds are dispersed | Part of seed which helps in dispersal |
| 1. | |||
| 2. | |||
| 3. |
Answer:
Solution to Extended Learning Problem 3
4. Suppose there is one member of a particular kind of organism in a culture dish, which doubles itself in one hour through asexual reproduction. Work out the number of members of that kind of organism which will be present in the culture dish after ten hours. Such a colony of individuals arising from one parent is called a “clone”.
Answer:
Solution to Extended Learning Problem 4
Solutions to In Text Questions of NCERT Class 7 Science Chapter 8 Reproduction in Plants:
1. (Page 82) How do plants reproduce?
Answer:
Plants reproduce using two main types of reproduction, namely asexual reproduction and sexual reproduction. The modes of asexual reproduction are vegetative propagation, budding, fragmentation, spore formation etc. Sexual reproduction occurs in the flower using the male reproductive part called stamen and the female reproductive part called pistil.
2. (Page 82) What is the function of flowers in plants?
Answer:
The function of the flower is to carry out sexual reproduction using the male stamen and the female pistil. The stamen produces male gametes which fertilises the female gametes inside the ovary of the pistil to form a zygote. The zygote develops into the embryo from which new plants are born.
3. (Page 82) Paheli thought that new plants always grow from seeds. But, she has never seen the seeds of sugarcane, potato and rose. She wants to know how these plants reproduce.
Answer:
Sugarcane,potato and rose reproduce asexually by vegetative propagation using the vegetative parts of the plants like stems, buds etc. Specifically, sugarcane and rose can be reproduced using a cut portion of the stem of the parent and potato reproduces using the scars or ‘eyes’ on its body.
4. (Page 84) Boojho wants to know if there is any advantage of vegetative propagation.
Answer:
Vegetative propagation is advantageous because it easily happens using the vegetative parts of a single parent. These plants take less time to grow and bear fruits and flowers earlier. The new plants are exact copies of and retain the characters of the parent since they are produced from a single parent.
5. (Page 84) Remember that yeast is a single-celled organism. Let us see how they reproduce?
Answer:
Yeast reproduces using small bulb-like projections called buds growing out of the yeast cell. The bud gradually grows bigger and gets detached from the parent cell to form a new yeast cell. Sometimes a chain of buds is formed which quickly produces a large number of yeast cells.
6. (Page 86) Boojho wants to know how the male gamete in the pollen grain reaches the female gamete present on the ovule.
Answer:
When the pollen grain containing male gametes land on the stigma it germinates and produces a pollen tube. The tube grows downwards through the style and reaches the ovule. The male gamete inside the pollen is released which travels down the pollen tube and fuses with the female gamete.
7. (Page 87) Boojho wants to know why flowers are generally so colourful and fragrant. Is it to attract insects?
Answer:
Flowers are generally so colourful and fragrant to attract insects which helps in pollination. The pollen grains from the anther stick to the body of the visiting insects and travel with them to reach the stigma of another flower of the same type for successful pollination.
8. (Page 88) What do you think will happen if all seeds of a plant were to fall at the same place and grow there?
Answer:
The disadvantage of all seeds falling at the same place and growing there is severe competition with each other for sunlight, water, minerals and space, which would prevent them from growing into healthy plants. Also, the plant would be unable to colonize new habitats for wider distribution which reduces the chances of survival.
Solutions to All Activities of NCERT Class 7 Science Chapter 8 Reproduction in Plants:
1. Complete Activity 8.1 (Page 82). Cut a branch of rose or champa with a node. This piece of branch termed a cutting. Bury the cutting in the soil. A node is a part of the stem/branch at which a leaf arises. Water the cutting every day and observe its growth. Observe and record the number of days taken for roots to come out and new leaves to arise. Try the same activity by growing money plant in a jar of water and record your observations.
Answer:
2. Complete Activity 8.2 (Page 83). Take a fresh potato. Observe the scars on it with the help of a magnifying glass. You may find bud(s) in them. These scars are also called “eyes”. Cut the potato into small portions, each of an eye and bury them in the soil. Water the pieces regularly for a few days and observe their progress. What do you find? Likewise you can also grow ginger or turmeric.
Answer:
3. Complete Activity 8.3 (Page 84). Take a piece of yeast cake or yeast powder from a bakery or a chemist shop. Take a pinch of yeast and place it in a container with some water. Add a spoonful of sugar and shake to dissolve it. Keep it in the warm part of a room. After an hour, put a drop of this liquid on a glass slide and observe under a microscope. What do you observe?
Answer:
4. Complete Activity 8.4 (Page 86). Take a mustard/ China rose/ petunia flower and separate its reproductive parts. Study the various parts of a stamen and pistil.
Answer:
Extra Questions to Complement Solutions to NCERT Class 7 Science Chapter 8 Reproduction in Plants:
Very Short Answer Type Questions:
1. What is known as reproduction?
Answer:
The production of new individuals from their parents is known as reproduction.
2. What is meant by vegetative parts of a plant?
Answer:
The parts of the plant like roots, stems and leaves which are involved in growth and development and are not involved in sexual reproduction.
3. Are vegetative parts of a plant used for reproduction?
Answer:
Vegetative parts of a plant are used in asexual reproduction but do not participate directly in sexual reproduction.
4. Name a plant that can reproduce both sexually and asexually?
Answer:
Onion plant can reproduce both sexually and asexually.
5. What are the two main types of plant reproduction?
Answer:
The two types of plant reproduction are sexual and asexual reproduction.
6. Are flowers involved in asexual reproduction?
Answer:
No, flowers are involved in sexual reproduction.
7. How many ovules are present in the ovary of each plant?
Answer:
Depending on the plant species, there are one or multiple ovules present in the ovary.
8. What are spores in plants?
Answer:
Spores are small, single-celled structures produced by plants like fungi, algae, fern etc that participate in asexual reproduction.
9. How are fungal spores dispersed?
Answer:
Fungal spores are dispersed by animals, insects, wind, water and rain.
10. What are the favourable conditions for germination of spores?
Answer:
The favourable conditions for germination of spores are moisture, suitable temperature, oxygen and nutrients.
Multiple Choice Questions:
1. Which of following parts of the plant is not vegetative?
(a) Root
(b) Stem
(c) Leaf
(d) Flower
Answer: (d) Flower. Flowers are directly involved in sexual reproduction and are not vegetative.
2. Which of these plants will produce an offspring which is mostly identical to the parent?
(a) Bryophyllum
(b) Mustard
(c) Sunflower
(d) Coconut
Answer: (a) Bryophyllum. Bryophyllum is the only plant that produced asexually and therefore has traits which are mostly identical to the parent.
3. The ‘eye’ of the potato plant is what (NCERT Exemplar)
(a) the root is to any plant.
(b) the bud is to a flower.
(c) the bud is to Bryophyllum leaf.
(d) the anther is to stamen.
Answer: (c) the bud is to Bryophyllum leaf. Both the ‘eye’ of potato plant and the ‘bud’ of Bryophyllum leaf are sources of vegetative propagation and formation of new plants.
Short Answer Type Questions:
1. What are the advantages of asexual reproduction over sexual reproduction in plants?
Answer:
The advantages of asexual reproduction in plants are:
- Rapid reproduction and efficient use of plant resources because the elaborate process of formation of flowers, fruits, seeds and pollination is not required.
- The offspring retains the characters of the single parent, so desirable traits can be retained.
2. How can an onion plant reproduce?
Answer:
Onion plants can reproduce both sexually and asexually:
- Onion plants reproduce sexually by formation of flowers and seeds.
- They can reproduce asexually by vegetative propagation through the formation of bulbs. The stored nutrients in the bulb are used for sprouting new plants.
3. What is the difference between node and axil?
Answer:
A node is the part of the stem/branch from which a new leaf arises whereas the axil is the point of attachment of the leaf at the node.
4. You know that rose or champa can reproduce using vegetative parts such as the stem. What is a second source of reproduction?
Answer:
Inrose or champa asexual reproduction happens by vegetative propagation from the buds in the axil of leaves called axillary buds. These buds sprout shoots which eventually develop into new plants.
5. Are two plants always necessary for sexual reproduction?
Answer:
No, sexual reproduction can happen in the same plant if the pollen grains from the anther land on the stigma of the same flower or another flower in the same plant. This is known as self-pollination.
6. Identify the organism in the picture below and describe how it reproduces.
Answer: The organism is an alga called spirogyra.Spirogyra reproduces both sexually and asexually:
Sexual reproduction happens when two adjacent filaments join using conjugation tubes through which contents of the two filaments mix together.
Asexual reproduction happens by simple fragmentation of algae filaments into multiple fragments which grow into new individuals and continue the process.
7. What characteristics of spores released by plants such as fungi help in their dispersal?
Answer:
Spores are easily dispersed long distances because:
- Spores are small, lightweight and have special structural characteristics which help them to float in air and travel long distances.
- They have hard protective coatings to withstand unfavourable conditions such as high temperature and low humidity which helps in survival.
- They have sticky surfaces which facilitates dispersal.
8. How does reproduction happen using spores?
Answer:
Asexual reproduction happens using spores by the following process:
- Sporangia of parent plant release the mature spores present inside.
- The spores are dispersed long distances by agents such as animals, insects, wind, water and rain.
- When the spores land in a favourable environment containing moisture they germinate to form new plants.
9. Distinguish between unisexual and bisexual flowers giving examples of each.
Answer:
Unisexual flowers contain either the male reproductive part stamen or the female reproductive part pistil, for example papaya, cucumber, squash. Bisexual flowers have both the male reproductive part stamen and the female reproductive part pistil in the same flower, for example rose, sunflower.
10. Why do pollen grains remain preserved for a long time?
Answer:
Pollen grains have a tough outer protective coating which helps it withstand physical damage during transportation by wind, animals, insects etc. The coating helps to retain water and is resistant to high temperatures which prevents dehydration. The coating is also resistant to chemical compounds and even attacks from bacteria, microbes and pathogens.
Long Answer Type Questions:
1. What are abiotic and biotic pollinating agents?
Answer:
Abiotic pollinating agents are non-living factors which facilitate the process of pollination in plants like wind, water, rain, gravity, ballistic etc:
Wind: This is the most common type of abiotic pollinating agent using which lightweight pollen grains can be effectively dispersed. Examples: grasses, cereals, conifers etc.
Water: Inaquatic plants pollen grains are transported by water from one flower to another. Examples: waterweed.
Rain: When raindrops fall on a flower the impact can cause the pollen grains to get dislodged and land on the female reproductive organ. Examples: Orchid (Acampe Rigida).
Gravity: Pollen grains fall from the male anther to the female stigma of the flower due to gravity.
Ballistic: Someplants havespecialised pollen ejection mechanisms which work to spray pollen into the surroundings. Examples: Synaphea stenoloba.
Biotic pollinating agents are living organismswhich facilitate the process of pollination by carrying pollen on their bodies.
Insects: When insects like bees, butterflies land on a flower to collect nectar the pollen grains stick to their bodies and are carried to other flowers, thereby completing the process of pollination.
Birds: Bright colours and scents of flowers attract birds such as hummingbirds which in the process of drinking nectar, carry away the pollen grains on their bodies to distant flowers to complete pollination.
Other Animals: Mammals such as rodents, bats and reptiles such as lizards also participate in the process of pollination.
2. List similarities and dissimilarities between spores and seeds.
Answer: The similarities between spores and seeds are as follows:
| Spores | Seeds |
| (i) Spores are dispersed over long distances via agents such as wind, water, animals etc. | (i) Seeds are also dispersed over long distances via similar agents such as wind, water, animals etc. |
| (ii) Spores are resistant to physical, chemical and microbial damage due to their protective outer coating. | (ii) Some seeds also have a protective outer coating which prevents them from damage. |
| (iii) Spores germinate under favourable conditions. | (iii) Seeds also germinate under favourable conditions. |
The dissimilarities between spores and seeds are as follows:
| Spores | Seeds |
| (i) Spores are single-celled organisms. | (i) Seeds are multicellular, contain an embryo and are protected by a seed coat. |
| (ii) Smaller in size. | (ii) Larger in size. |
| (iii) Produced inside sporangia. | (iii) Produced due to the process of fertilisation taking place inside the ovule of a flower. The ovule then develops into a seed. |
| (iv) Participate in asexual reproduction. | (iv) Seeds are involved in sexual reproduction. |
| (v) Mostly depend on external sources for nutrients. | (v) Seeds get nutrients from inside. |
| (vi) Less resistant to harsh environmental conditions. | (vi) More resistant to harsh environmental conditions. |
3. Describe the seed dispersal mechanism in each of the following cases:
Answers:
(a) In case of cottonwood plant, seeds are dispersed by the wind. The white fluffy structure surrounding the seed shown in Figure (a) helps it travel long distances with the wind.
(b) In case of mangrove plants, seeds are dispersed by water. Mangrove plants grow near the sea, rivers, estuaries etc as shown Figure (b). The seeds drop into the water, float and are carried for long distances in water currents, tides etc.
(c) Dandelion seeds are dispersed by the wind. The fluffy ‘pappus’ consisting of feathery bristles present on the seed as shown Figure (c) help it to catch the wind and travel long distances.
Fill in the Blanks:
sori, Xanthium, self-pollination, ovary, yeast, sporangia, ovule
(a) _________ is a single-celled organism.
(b) A fungus produces spores inside _________ and a cluster of the latter is called _________.
(c) After fertilisation, _________ develops into a fruit and seeds are formed from the _________.
(d) Seed dispersal happens via animals in case of _________.
(e) If the pollen lands on the stigma of another flower of the same plant it is called _________.
Answers:
(a) Yeast is a single-celled organism.
(b) A fungus produces spores inside sporangia and a cluster of the latter is called sori.
(c) After fertilisation, ovary develops into a fruit and seeds are formed from the ovule.
(d) Seed dispersal happens via animals in case of Xanthium.
(e) If the pollen lands on the stigma of another flower of the same plant it is called self-pollination.
Match and Pair:
1. Match the items of Column I with suitable items in Column II:
| Column I | Column II |
| (a) Spirogyra | (i) Reproduce using roots |
| (b) Sweet Potatoes | (ii) Reproduction using spores |
| (c) Fern | (iii) Embryo |
| (d) Zygote | (iv) Egg |
| (e) Female gamete | (v) Algae |
Answer: The correct table is shown below:
| Column I | Column II |
| (a) Spirogyra | (v) Algae |
| (b) Sweet Potatoes | (i) Reproduce using roots |
| (c) Fern | (ii) Reproduction using spores |
| (d) Zygote | (iii) Embryo |
| (e) Female gamete | (iv) Egg |
++++++++++++++
Frequently Asked Questions (FAQs) on NCERT Solutions to Class 7 Science Chapter 8 Reproduction in Plants:
An expert team of Indian and foreign-educated teachers, engineers and scientists have crafted these solutions in a scientific manner taking care to answer all your questions and clear your concepts. The exercise solutions, extended learning activities, in-text questions, activities and extra questions have been thoroughly explained with attractive figures wherever necessary to further help in understanding and retention.
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The following topics are covered:
8.1 – Modes of Reproduction
Asexual Reproduction
Vegetative Propagation
Budding
Fragmentation
Spore Formation
8.2 – Sexual Reproduction
Pollination
Fertilisation
8.3 – Fruits and Seed Formation
8.4 – Seed Dispersal
Here are the number of problems for the chapter:
(i) 1 Fill in the Blanks Type Question (Question 1)
(ii) 3 Long Answer Type Questions (Questions 2, 6, 7)
(iii) 3 Short Answer Type Questions (Questions 3, 4, 8)
(i) 1 Diagram Based Question (Question 5)
(ii) 1 Match and Pair Type Question (Question 9)
(iii) 1 Tick the Correct Answer Question (Question 10)
We recommend that you understand the mechanisms of different modes of asexual reproduction and also the mechanism of sexual reproduction thoroughly for your exams. The chapter ends with a discussion on seed dispersal which is interesting and also important. We have included excellent diagrams in our solutions and explanations which will help you both learn and enjoy the subject.
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