Class 7 Science Chapter 8 Question Answers - Reproduction in Plants

Short Types Questions

Vegetative reproduction is a type of asexual reproduction in plants where new plants are produced from vegetative parts of the parent plant. An example of vegetative reproduction is the propagation of rose plants from stem cuttings.

Q.2. Name the different types of underground stems.

The different types of underground stems are rhizomes, bulbs, tubers, and corms.

Q.3. What is pollination?

Pollination is the transfer of pollen grains from the male reproductive organ of a flower (anther) to the female reproductive organ (stigma) of the same or a different flower.

Q.4. Explain the process of fertilization in plants.

Fertilization is the fusion of the male gamete (pollen) with the female gamete (ovule) to form a zygote, which develops into an embryo. After pollination, the pollen grain germinates to form a pollen tube, which grows towards the ovary. The male gamete travels through the pollen tube and fuses with the female gamete inside the ovule, leading to fertilization.

Q.5. What is seed dispersal? Name any two agents of seed dispersal.

Seed dispersal is the process by which seeds are spread to different locations from the parent plant. Two agents of seed dispersal are wind and animals.

Long Types Questions

Asexual reproduction is the process of reproduction in which a single individual produces offspring without the involvement of another individual. In plants, there are various ways of asexual reproduction such as vegetative reproduction, reproduction through roots, reproduction through stems, and types of underground stems such as rhizomes, bulbs, tubers, and corms. For example, plants like potato, onion, ginger, and turmeric reproduce asexually through underground stems. In vegetative reproduction, the new plant is formed from vegetative parts of the parent plant such as leaves, roots, and stems. For example, Bryophyllum reproduces vegetatively from the buds present on the margins of its leaves. In asexual reproduction, the offspring is genetically identical to the parent plant.

Q.2. What is sexual reproduction in plants? Explain the process of pollination and fertilization in detail.

Sexual reproduction is the process of reproduction in which two individuals, a male and a female, are involved in producing offspring. In plants, sexual reproduction takes place through the process of pollination and fertilization. Pollination is the transfer of pollen grains from the male reproductive organ of a flower to the female reproductive organ of another flower. Pollination can be of two types: self-pollination and cross-pollination. In self-pollination, the pollen grains from the anther of a flower are transferred to the stigma of the same flower. In cross-pollination, the pollen grains are transferred from the anther of one flower to the stigma of another flower. Fertilization is the process of fusion of the male and female gametes to form a zygote. The zygote develops into a seed, which is protected by a fruit. Fertilization takes place in the ovary of the flower.

Q.3. What is vegetative reproduction? Explain the different methods of vegetative reproduction in plants. 

Vegetative reproduction is the process of reproduction in which a new plant is produced from vegetative parts of the parent plant such as leaves, roots, and stems. There are various methods of vegetative reproduction in plants such as cutting, grafting, layering, and division. In cutting, a part of the stem or leaf is cut and planted in soil or water. The cutting develops roots and grows into a new plant. In grafting, a part of one plant is attached to another plant to form a new plant. In layering, a branch of a plant is bent down and covered with soil. The branch develops roots and grows into a new plant. In division, the parent plant is divided into two or more parts, and each part is planted separately to form a new plant.

Q.4. Explain the process of seed dispersal in plants. Give examples of different ways in which seeds are dispersed. 

Seed dispersal is the process of spreading seeds away from the parent plant. It is important for the survival of plants as it helps to prevent overcrowding and competition for resources. There are various ways in which seeds are dispersed such as wind, water, animals, and explosive action. In wind dispersal, the seeds are light and have wings or hairs that help them to float in the air. Examples of plants that have wind-dispersed seeds are dandelion and maple. In water dispersal, the seeds are buoyant and can float on water. Examples of plants that have water-dispersed seeds are coconut and water lily. In animal dispersal, the seeds are either ingested by animals and passed out in their droppings or get attached to the fur or feathers of animals. Examples of plants that have animal-dispersed seeds are apple and strawberry. In explosive action, the seeds are ejected forcefully from the fruit or seed pod. Examples of plants that have explosive-dispersed seeds are balsam and pea.

Q.5. Explain the process of germination of a seed. What are the conditions required for the germination of a seed?

Germination is the process by which a seed develops into a new plant. The process of germination starts when the seed absorbs water and swells up. The seed coat then splits, and the root emerges first, followed by the shoot. The root anchors the plant in the soil and absorbs water and nutrients from the soil. The shoot grows towards the light and develops leaves for photosynthesis. The conditions required for the germination of a seed are water, oxygen, and a suitable temperature. Water is required for the seed to absorb and activate the enzymes necessary for germination. Oxygen is required for the respiration of the seed, which provides energy for growth. A suitable temperature is required for the enzymes to function optimally. Different seeds have different requirements for temperature, and some seeds require a period of cold or hot temperatures to break dormancy before germination can occur.