PSEB Punjab Board Class 7 Science Textbook Solution Chapter 12 Reproduction in Plants Exercise Questions and Answers
Q.1 Fill in the blanks:
1. Anther and filament form the ………… of a flower.
Answer:- stamens.
2. In……………. reproduction seeds are formed.
Answer:- asexual reproduction.
3. Flowers having both stamens and pistils are called……………
Answer:- bisexual flowers.
4. ……………. is an asexual mode of reproduction.
Answer:- Binary fission.
Q.2 True or false:
1. Yeast produced by sexual and asexual means.(T/F)
Answer:- False.
2. Pollen grains are the male gametes of the flower.(T/F)
Answer:- True.
3. Ginger is a steam which bears nodes and internodes.(T/F)
Answer:- True.
4. Cutting and grafting are natural means of reproduction.(T/F)
Answer:- False.
Match the column
1. Sweet potato – f) adventitious root
2. Potato – g) stem root
3. Leaf buds – b) Bryophyllum
4. Grafting – c) artificial propagation
5. Tissue culture- a) micropropagation
6. Bud – d) yeast
7. Fragmentation – e) spirogyra
Q.4 Very short answer type questions
1. In which mode of reproduction new plants are formed from only one parent ?
Answer:- In asexual reproduction new plants are formed from only one parent.
2. Which part of the flower develops into fruit?
Answer:- The ovary of the flower develops into fruit.
3. How does yeast multiply?
Answer:- By asexual reproduction yeast multiply.
4. Give one example where air helps in pollination.
Answer:- TRIDAX plant is an example of pollination.
5. Name the reproductive parts of a flower.
Answer:- Ovary and stigma are the reproductive parts of a flower.
Q.5 Short answer type questions
1. Name different methods of asexual reproduction in plants.
Answer:- 1) binary fusion, 2) budding, 3) fragmentation, 4) spore formation, 5) regeneration, are the different methods of asexual reproduction in plants.
2. What is the artificial propagation of plants?
Answer:- Artificial propagation is the process of growing new plants by artificial methods.
Four methods of artificial propagation are grafting, cutting, layering and tissue culture.
3. What is the tissue culture technique of micropropagation?
Answer:- Micropropagation is the artificial process of producing plants vegetatively through tissue culture or cell culture techniques. In this artificial process of propagation, plants are produced invitro by asexual means of reproduction or by vegetative propagation.
4. Describe advantages of seed dispersal.
Answer:- (i) Seed dispersal prevents the overcrowding of plants in an area.
(ii) Seed dispersal prevents the competition for water, minerals and sunlight among the same kind of plants.
(iii) Seed dispersal helps the plants to grow in new places (or new habitats) for wider
distribution, are the advantages of seed dispersal.
5. What is germination? What are the conditions needed for the germination?
Answer:- On reaching the moist soil, the seed swells up by imbibing water. The embryo
starts germinating, Its radical grows down into the soil and forms the root. The plumule
grows upward. In the air, leaves form the shoots of the young plant.
Q.7 Long answer type questions:
1. Describe different kinds of asexual reproduction with examples.
Answer:- Asexual reproduction is a mode of reproduction in which a new offspring is
produced by a single parent. The new individuals produced are genetically and physically identical to each other, i.e., they are the clones of their parents.
There are different types of asexual reproduction:
- Binary Fission
- Budding
- Fragmentation
- Vegetative Propagation
- Sporogenesis
During binary fission, the parent cell divides into two cells. The cell division patterns vary in different organisms, i.e., some are directional while others are non-directional. Amoeba and euglena exhibit binary fission.
Fragmentation is another mode of asexual reproduction exhibited by organisms such as
spirogyra, planaria, etc. The parent body divides into several fragments and each fragment develops into a new organism.
Regeneration is the power of growing a new organism from the lost body part. For eg., when a lizard loses its tail, a new tail grows. This is because the specialized cells present in the organism can differentiate and grow into a new individual. Organisms like hydra and planaria exhibit regeneration.
Budding is the process of producing an individual through the buds that develop on the
parent body. Hydra is an organism that reproduces by budding. The bud derives nutrition and shelter from the parent organism and detaches once it is fully grown.
Asexual reproduction in plants occurs through their vegetative parts such as leaves, roots, stems, and buds. This is called vegetative propagation. For example, potato tubers,runners/stolon, onion bulbs, etc., all reproduce through vegetative propagation.
Spore formation is another means of asexual reproduction. During unfavorable conditions, the organism develops sac-like structures called sporangium that contain spores. When the conditions are favorable, the sporangium burst opens and spores are released that germinate to give rise to new organisms.
2. Explain different ways with examples in which plants can be reproduced vegetatively by artificial means.
Answer:- This is a type of vegetative reproduction carried out by humans in the fields and laboratories. The most common types of vegetative reproduction occurring artificially include:
Cutting
In this, a part of a plant, specifically a stem or leaf is cut and planted in the soil. These
cuttings are sometimes treated with hormones to induce root development. The new plant is formed from the adventitious roots developing from the cutting.
Grafting
In this, the cutting from some other plant is attached to the stem of a plant rooted in the
ground. The tissues of the graft become integrated with the tissues of the rooted plant and develop as a single plant over time.
Layering
In this, the stem of the plant is bent to the ground and covered with soil. Adventitious roots emerge from the plant parts covered with the soil. This attached stem with developing roots is known as a layer.
Tissue Culture
In this, the plant cells from different parts of a plant are cultured in the laboratory to develop a new plant. This technique is helpful in increasing the number of rare and endangered plant species that are unable to grow under natural conditions.
3. What is pollination? What are the two types of pollination? Discuss the different agents of pollination with examples.
Answer:- Pollination is of two types :
(i) Self-pollination: In this process, the transfer of pollen grains takes place from the anther of a flower to the stigma of the same flower (bisexual).
(ii) Cross-pollination: In this process, the pollen grains are transferred from one flower to the stigma of another flower. Cross-pollination may take place between two flowers on the same plant or between flowers on different plants of the same species.
4. Explain the process of fertilization.
Answer:- On reaching the stigma, a thin pollen tube grows out from the pollen grain. It
extends through the style, reaches the ovary and enters the ovule. Here the fusion of male and female gametes take place. The process of fusion of a male gamete and a female gamete is called fertilization.
5. List the different steps in the formation of seeds and fruits.
Answer:- After fertilization the ovary grows into a fruit and other parts of the flower fall off. The ovules develop into seeds. A seed is a mature ovule that contains the embryo and the stored food. It is enclosed by a protective covering called a seed coat.
Fruits may be fleshy and juicy or dry and hard. Mango, apple, orange are fleshy and juicy fruits whereas almonds and walnuts are dry and hard fruits.
6. What is dispersal? Explain with examples the different ways in which seeds get dispersed.
Answer:- Seed Dispersal is an adaptive mechanism in all seed-bearing plants,
participating in the movement or transport of seeds away from their parent plant to ensure the germination and survival of some of the seeds to adult plants. There are many vectors to transport the seed from one place to another.
Types of seed dispersal:-
Dispersal by Wind
Fruits and seeds which are small and light are generally scattered by wind. Seeds of maple and drumsticks have wings for floating in the air to long distances. Light seeds of grass, hairy seeds of Akk, dandelion and cotton, and hairy fruits of sunflower are blown to far away places by wind.
Dispersal by Water
The fruits and seeds of plants like those of water lily, lotus and coconut float on water
surface and are carried to far off places by water currents. Coconut has a fibrous coat with hard covering. It is carried away to long distances by water currents without being damaged.
Dispersal by Animals\
Seeds dispersed by animals have spines or hooks which cling to the bodies of animals and are carried to long distances as in Xanthium and Urena.
Man, animals and also birds eat the pulp or the edible part of fleshy fruits and throw their seeds. This helps in their dispersal. The small and undigested seeds are excreted out of their body and dispersed. The seeds of guava and raspberries are dispersed this way.
Explosive Mechanism
Fruits and seeds of Balsam, wild Pea, Geranium, and Castor burst with sudden jerks and get scattered away from their parent plant.
Dear Student, I appreciate your efforts and hard work that you all had put in. Thank you for being concerned with us and I wish you for your continued success.
For more update, follow this page ⇒ PSEB Notes and Solutions