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Reproduction in Plants Class 7 Notes Science Chapter 8

Do you know how a new plant grows? If you answer that plants grow because of seeds then let me ask you a question: have you ever seen sugarcane, potato, or rose seeds? No right? Well, there are various interesting ways in which a new plant can grow. 

Modes of Reproduction

  • Plants consist of roots, stems, and leaves, collectively termed as vegetative parts.
  • After a growth period, most plants develop flowers, such as mango trees blooming in spring.
  • Flowers are crucial for the reproduction of plants and serve as their reproductive parts.
  • The flowers of plants eventually give rise to fruits, like juicy mangoes enjoyed in summer.
  • Although we typically consume the fruits and discard the seeds, these seeds play a vital role in germination and the formation of new plants.

Reproduction in plants is categorised into two types:

Reproduction in Plants Class 7 Notes Science Chapter 8

Asexual Reproduction

Reproduction in Plants Class 7 Notes Science Chapter 8

1. Vegetative Propagation

It is a type of asexual reproduction in which new plants are produced from roots, stems, leaves and buds. Since reproduction is through the vegetative parts of the plant, it is known as vegetative propagation.

(i) Vegetative Reproduction by Stem 

  • New plants are obtained from the stem by the cutting method. 
  • In this method, the small part of stem is removed by making a cut with a sharp knife. 
  • The stem cutting must have some buds on it. 
  • Now the lower end of stem cutting is buried in the moist soil. 
  • The upper part of cutting having bud on it, is kept above the soil. 
  • After few days, this cutting develops new roots. 
  • The bud grows and produces a shoot (i.e. branches with leaves). 
  • Thus, a new plant is produced which is exactly similar to the parent plant, e.g. rose, champa, grapes, sugarcane, banana, cactus, etc. 

Stem CuttingStem Cutting(ii) Vegetative Reproduction by Leaves, Roots and Bulbs

  • Bryophyllum plant has buds on the edges of its leaves. 
  • When the buds come in contact with moist soil, each bud is capable of growing into a new plant. 
  • Plants that use buds for vegetative propagation are potato, ginger and turmeric, amongst others. 
  • Roots that store food are known as tubers. 
  • Such roots are the food storage tanks for the plants.
  • When these tubers are detached from the parent plant and planted in the soil, they grow into a new plant. 
  • A plant that grows from a single root tuber, and then branches and rebranches, thereby covering a large area.
  • A number of root tubers are produced by a single plant.
  • Another plant that is grown from the tuber is the dahlia plant.

Vegetative ReproductionVegetative Reproduction

2. Budding

  • Yeast is a single-celled organism.
  • Reproduction process involves the formation of a bud, a small bulb-like projection from the yeast cell.
  • The bud gradually grows, detaches from the parent cell, and develops into a new yeast cell.
  • The new yeast cell matures and produces additional yeast cells.
  • Occasionally, a chain of buds is formed as another bud arises from the initial bud.
  • Continuous repetition of this process results in the rapid production of a large number of yeast cells

Budding in yeast CellsBudding in yeast Cells

3. Fragmentation

  • Algae like Spirogyra generally reproduce by the process of fragmentation in which they divide themselves into multiple parts.
  • As soon as the algae finds enough water and nutrients, it fragments and grows into new individuals.
  • This process continues and algae multiply quickly in a short period.

FragmentationFragmentation

4. Spore Formation

  • Some plants contain spores that float in the air and cause asexual reproduction.
  • A spore has a hard protective cover that protects it from unfavorable environmental conditions like temperature and humidity.
  • As a result, the spores can travel and survive for a long duration of time.
  • As soon as they find favorable conditions such as moisture and nutrients, they germinate and form new plants.
  • For Example, Moss and ferns propagate in this way.

Spore FormationSpore Formation

Question for Chapter Notes: Reproduction in Plants
Try yourself:How do plants reproduce through asexual reproduction?
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Sexual Reproduction

In sexual reproduction, new plants are obtained from seeds.
  • The flowers of a plant are its reproductive organs that participate in the sexual reproduction process.
  • The male reproductive parts of a plant are called Stamen.
  • The female reproductive parts of a plant are called Pistil.The new plant produced contains the characteristics of both plants that participate in the sexual reproduction.
  • The stamen consists of Anther that has pollen grains. 
  • These pollen grains produce male gametes.
  • The pistil consists of three parts:
    • Stigma – It is a sticky surface where pollen grains get attached.
    • Style – It is a tube-like structure which connects the stigma and the ovary.
    • Ovary – It contains eggs in which the female gametes or eggs are formed.

Sexual ReproductionSexual Reproduction

Types of Flower

  • Bisexual Flowers- Some flowers contain both stamen and pistil and are called Bisexual Flowers. Eg. Lily, rose, brinjal, hibiscus, petunia, mustard etc.
  • Unisexual Flowers- Some flowers contain either the statement or the pistil and hence are called Unisexual Flowers. Eg. papaya, watermelon, cucumber, coconut etc.

Bisexual and Unisexual FlowersBisexual and Unisexual Flowers

Pollination

The transfer of pollen from the anther to the stigma of a flower constitutes pollination. 

Pollination Process Overview:

  • Pollen grains have a protective coat to prevent drying up.
  • They are light and can be transported by wind, water, or insects.

Insect-mediated Pollination:

  • Insects visit flowers and unintentionally carry pollen on their bodies.

PollinationPollination

There are two types of pollination:

Self-Pollination:

  • Pollen lands on the stigma of the same flower or another flower of the same plant.
  • This process is known as self-pollination.

Cross-Pollination:

  • Pollen from a flower lands on the stigma of a different plant of the same kind.
  • This is referred to as cross-pollination.

Types of PollinationTypes of Pollination

The Fertilization Process

  • A zygote is formed as the fusion between the male and female gametes occurs.
  • This process of formation of the zygote is called Fertilization.
  • Then the zygote develops and turns in an embryo.

Fertilization ProcessFertilization Process

Question for Chapter Notes: Reproduction in Plants
Try yourself:
What is the function of the stigma in a flower?
View Solution

Fruits and Seeds Formation

  • Fertilisation leads to the transformation of the ovary into a fruit.
  • Other parts of the flower fall off during this process.

  • The fruit represents the matured ovary.

  • Seeds develop from the ovules in the ovary.

  • Each seed consists of an embryo protected by a seed coat.

Fruits can be categorised into two types based on texture:

  • Some fruits, like mangoes and oranges, are fleshy and juicy.
  • Others, such as almonds and walnuts, have a hard texture.

Seed dispersal

  • Plants of the same type grow in different places due to seed dispersal.
  • Seeds are scattered to various locations naturally.

Consequences of Limited Dispersion:

If all seeds of a plant fall and grow in the same place:

  • Severe competition for sunlight, water, minerals, and space occurs.
  • Results in unhealthy plant growth.

Methods of Seed Dispersal:

  • Wind: Winged seeds (e.g., drumstick, maple) and light seeds of grasses get blown to distant places.
  • Water: Some seeds develop floating ability (e.g., coconut) for dispersal by water.
  • Animals: Spiny seeds with hooks attach to animals, carrying seeds to distant places (e.g., Xanthium, Urena).

Mechanisms of Dispersion:

  • Bursting Fruits:
    • Some fruits burst with sudden jerks, scattering seeds far from the parent plant.
    • Examples include castor and balsam.

Question for Chapter Notes: Reproduction in Plants
Try yourself:
What is the purpose of seed dispersal in plants?
View Solution

Reproduction in Plants Class 7 Notes Science Chapter 8

The document Reproduction in Plants Class 7 Notes Science Chapter 8 is a part of the Class 7 Course Science Class 7.
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FAQs on Reproduction in Plants Class 7 Notes Science Chapter 8

1. What are the two main modes of reproduction in plants?
Ans. The two main modes of reproduction in plants are asexual reproduction and sexual reproduction.
2. How do plants form fruits and seeds?
Ans. Plants form fruits and seeds through the process of sexual reproduction, where pollen from the male reproductive structure (stamen) fertilizes the ovule in the female reproductive structure (pistil).
3. What is seed dispersal and why is it important for plants?
Ans. Seed dispersal is the process by which seeds are spread and scattered away from the parent plant. It is important for plants as it helps in the distribution of seeds to new locations, reducing competition among offspring and increasing the chances of survival and growth.
4. Can plants reproduce without seeds?
Ans. Yes, plants can reproduce asexually without seeds through methods such as budding, fragmentation, and spore formation.
5. How do seeds ensure the survival and growth of plants?
Ans. Seeds contain the embryo of the plant along with stored food and a protective seed coat. This ensures that the plant has the necessary resources to germinate, grow, and establish itself in a new environment.
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