NCERT Solutions for Class 7 Science - Reproduction in Plants

Q1. Fill in the blanks:
(a) Production of new individuals from the vegetative part of the parent is called _____________.
Ans: Production of new individuals from the vegetative part of the parent is called vegetative propagation.

Vegetative propagation is a type of asexual reproduction in plants, where new plants grow from non-reproductive plant parts, such as roots, stems, or leaves.

(b) A flower may have either male or female reproductive parts. Such a flower is called _____________.
Ans: A flower may have either male or female reproductive parts. Such a flower is called unisexual.

Unisexual plants have separate male and female reproductive structures, with male and female flowers on either the same or different plants. This prevents self-fertilization and encourages cross-pollination between different plants.

(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 _____________.
Ans: 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.

Pollination in plants is the process of transferring pollen from the male reproductive organ (stamen) to the female reproductive organ (pistil), allowing fertilization and the production of seeds. 

(d) The fusion of male and female gametes is termed as _____________.
Ans: The fusion of male and female gametes is termed as fertilization.

Fertilization in plants occurs when male reproductive cells (pollen) unite with female reproductive cells (ova), resulting in the formation of a new plant embryo within a seed. 

(e) Seed dispersal takes place by means of _____________, _____________ and _____________.
Ans: Seed dispersal takes place by means of wind, water and animals.

Seed dispersal in plants is the process by which seeds are transported away from the parent plant, promoting genetic diversity and reducing competition for resources. Various mechanisms, such as wind, water, animals, and self-propulsion, facilitate this movement of seeds.

Q2. Describe the different methods of asexual reproduction. Give examples.
Ans: The various modes of asexual reproduction in plants are as follows:

(i) Fission: Asexual reproduction through fission is a process where an organism splits into two or more separate individuals, each with the ability to grow and develop into a complete organism.

Example: Single-celled organisms like bacteria and some simple multicellular organisms like certain types of fungi.

(ii) Vegetative propagation: It is the ability of a plant to produce new plants from roots, stems, leaves, and buds.

Example: Potato, ginger.

(iii) Budding: It involves the formation of a new individual from a bulb-like projection called a bud. The bud grows and detaches from the parent to form a new individual. It is commonly observed in yeast.
(iv) Fragmentation: It is a form of asexual reproduction where a new organism is formed from the fragments of the parent body. It is the only mode of asexual reproduction in Spirogyra.
(v) Regeneration: Regeneration is the ability of an organism to regrow or replace lost or damaged body parts. It is a process by which new cells are produced to replace the lost or damaged ones. Some organisms, such as certain species of starfish, worms, and salamanders, possess remarkable regenerative abilities.
(vi) Spore formation: Many non-flowering plants reproduce through spore formation. Spores are tiny cells protected by a thick wall. Fungi such as bread molds reproduce asexually using this method.

Q3. Explain what you understand by sexual reproduction.
Ans: Sexual reproduction is a process by which offspring are produced through the combination of genetic material from two parent organisms, usually involving male and female gametes. This mode of reproduction is characterized by the fusion of male and female sex cells, or gametes, which contain half of the genetic information needed to create a new individual. The resulting zygote contains a complete set of genetic information, with half coming from each parent, and it undergoes a series of developmental stages to eventually form a new, genetically unique organism.

Q4. State the main difference between asexual and sexual reproduction.
Ans: Differences between sexual and asexual reproduction:

Q5. Sketch the reproductive parts of a flower.
Ans:

Q6. Explain the difference between self-pollination and cross-pollination.
Ans: Differences between self-pollination and cross-pollination:

Q.7. How does the process of fertilisation take place in flowers?
Ans: When pollen grain lands on stigma of the flower, it germinates and gives rise to a pollen tube that passes through the style and reaches the ovary of a pistil. When the pollen tube reaches an ovule, it releases the male gametes. A male gamete fuses with a female gamete in the ovule. This process is known as fertilisation. The cell which is formed after the fusion of a male and a female gamete is known as zygote. This zygote divides several times in order to form the embryo present inside the seed.

Q.8. Describe the various ways by which seeds are dispersed.
Ans: Seed dispersal occurs by the following agencies.
(i) Dispersal by animals: There are many ways by which birds and animals can disperse seeds.

• Example: birds and animals can eat the fruits and excrete the seeds away from the parent plant. 

(ii) Dispersal by wind: Seeds that get dispersed by wind are usually smaller in size or they have wings or hair-like structures.

• Example: winged seeds of drumsticks, hairy fruit of sunflowers, etc. are dispersed by wind.

(iii) Dispersal by water: Many aquatic plants or plants that live near water have seeds that can float and are carried away by water.

• Example: coconuts can float and are dispersed by water.

(iv) Dispersal by explosion: Sometimes the seeds are dispersed by the bursting of fruits with sudden jerks. The seeds get scattered or distributed far from the parent plant. 

• Examples of such plants are castor and balsam.

Q9. Match items in Column I with those in Column II:

Ans: 

Q10. Tick (√ ) the correct answer:
(a) The reproductive part of a plant is the
(i) leaf
(ii) Stem
(iii) Root
(iv) Flower
Ans: (iv) flower

The flower is the reproductive part of a plant, playing a crucial role in the plant's life cycle. It facilitates the fertilization process by producing seeds and fruits through the fusion of male and female gametes. Flowers contain reproductive organs, such as stamens and pistils, which enable them to reproduce and ensure the survival of their species. 

(b) The process of fusion of the male and female gametes is called
(i) Fertilisation
(ii) Pollination
(iii) Reproduction
(iv) Seed formation
Ans: (i) Fertilisation

Fertilisation is a crucial process in sexual reproduction that involves the fusion of male and female gametes, resulting in the formation of a zygote. This process ensures the transfer and combination of genetic material from both parents, contributing to genetic diversity in offspring. Fertilisation initiates the development of a new organism, ultimately leading to the growth and maturation of a new individual 

(c) Mature ovary forms the
(i) Seed
(ii) Stamen
(iii) Pistil
(iv) Fruit
Ans: (iv) fruit
Explanation: The mature ovary forms the fruit in a flowering plant. During the process of fertilization, the ovary develops and enlarges to protect and nurture the developing seeds. As the seeds mature, the ovary transforms into a fruit, which can aid in seed dispersal and provide nourishment for the plant's offspring. 

(d) A spore-producing plant is
(i) Rose
(ii) Bread mould
(iii) Potato
(iv) Ginger
Ans: (ii) Bread mould

Bread mould, scientifically known as Rhizopus stolonifer, is a type of fungus that reproduces through spore production. These spores are tiny, lightweight, and easily dispersed through the air, allowing the mould to spread and grow on various surfaces, such as bread. The presence of bread mould is a common occurrence in households and serves as a prime example of a spore-producing plant.

(e) Bryophyllum can reproduce by its
(i) Stem
(ii) leaves
(iii) Roots
(iv) Flower
Ans: (ii) leaves

Bryophyllum, a genus of succulent plants, has a unique ability to reproduce through its leaves. This process, known as vegetative reproduction, involves the formation of tiny plantlets along the margins of the leaves. These plantlets eventually grow roots and separate from the parent plant, developing into an independent, fully functional plant.