NCERT Solutions 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 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:
Asexual reproduction occurs without the production of seeds. Some common methods of asexual reproduction are:

• Vegetative Propagation: New plants grow from parts like roots, stems, leaves, or buds. Example: Rose, potato, ginger.
• Budding: New organisms grow from a bud on the parent organism. Example: Yeast.
• Fragmentation: The organism breaks into pieces, each of which grows into a new individual. Example: Spirogyra (alga).
• Spore Formation: Spores are released and grow into new individuals under favorable conditions. Example: Moss, ferns.

3. Explain what you understand by sexual reproduction.

Answer:
Sexual reproduction involves the fusion of male and female gametes to form a zygote. The male gamete (sperm) and female gamete (egg) unite during fertilization, leading to the formation of a zygote, which grows into a new individual. This process introduces genetic variation in the offspring.

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

Answer:

• Asexual Reproduction: Involves the production of new individuals from a single parent without the involvement of gametes. The offspring are genetically identical to the parent.
• Sexual Reproduction: Involves the fusion of male and female gametes, leading to the formation of a zygote. The offspring show genetic variation.

5. Sketch the reproductive parts of a flower.

Answer:
[Diagram of a flower showing the male and female reproductive parts]

• Male reproductive part: Stamen (Anther and Filament).
• Female reproductive part: Pistil (Stigma, Style, Ovary, and Ovule).

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

Answer:

• Self-pollination: Pollen grains from the same flower or from another flower on the same plant are transferred to the stigma of a flower.
• Cross-pollination: Pollen grains are transferred from the anther of a flower on one plant to the stigma of a flower on a different plant of the same species.

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

Answer:
Fertilisation in flowers takes place when the male gamete (pollen grain) travels down the pollen tube and reaches the ovule. The sperm cell fuses with the egg cell in the ovule, forming a zygote, which later develops into an embryo.

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

Answer:

• By Wind: Light seeds like those of maple and drumstick are carried by the wind.
• By Water: Some seeds like those of coconut float on water and are carried to different places.
• By Animals: Seeds like those of Xanthium and Urena are carried by animals. Some seeds also have hooks that attach to animal fur.
• By Explosion: Some fruits burst and scatter seeds away. Example: Castor, Balsam.

9. Match items in Column I with those in Column II:

10. Tick () the correct answer:

Extended Learning—Activities and Projects

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.
   • This activity helps understand how cacti reproduce and how vegetative propagation works for certain plants.
2. Visit a fruit market and collect as many local fruits as possible. Split the fruits and examine the seeds within. Look for any special characteristics in the fruits and their seeds.
   • This helps in understanding different methods of seed formation and dispersal.
3. Think of ten different fruit-bearing plants. Discuss with your teacher, parents, or agricultural experts and find out how their seeds are dispersed. Present your data in a table.
   • This activity encourages exploration of various seed dispersal mechanisms.
4. Suppose there is one member of a particular kind of organism in a culture dish, which doubles itself every hour through asexual reproduction. Work out the number of members of that kind of organism after ten hours.
   • This helps understand exponential growth and the concept of clones in asexual reproduction.