Reproduction In Plants Class 7 Notes Pdf Download
Arline Wallaert
Plant propagation is the process of creating new plants. There are two types of propagation: sexual and asexual. Sexual reproduction is the union of the pollen and egg, drawing from the genes of two parents to create a new, third individual. Sexual propagation involves the floral parts of a plant. Asexual propagation involves taking a part of one parent plant and causing it to regenerate itself into a new plant. The resulting new plant is genetically identical its parent. Asexual propagation involves the vegetative parts of a plant: stems, roots, or leaves.
Sexual reproduction requires genetic material (DNADNA) from two parents. The parent plants have male and female sex cells, called gametes. The genetic material from the male and female gametes combines to produce offspring. We call this process fertilization. The product of sexual reproduction are seeds.
Flowering plants reproduce sexually through a process called pollination. Flowers contain male sex organs called stamens and female sex organs called pistils. The anther is the part of the stamen that contains pollen. Pollen contains the male gametes. Pollen must be moved to a part of the pistil called the stigma for reproduction to take place.
Fragmentation is another form of asexual reproduction. It involves new plants growing from small parts of a parent plant that fall to the ground. This is one of the ways that plants like liverworts and mosses reproduce.
Horticulturists are people who study plants. They often use asexual reproduction through fragmentation to grow new plants. They do this by cutting a leaf or a stem off a plant and placing it in water or soil. This process is often called propagating from cuttings.
Fruits are classified as simple, aggregate or multiple (Figure 21). Simple fruits develop from a single ovary. They include fleshy fruits such as cherries and peaches (drupe), pears and apples (pome) and tomatoes (berries). Although generally referred to as a vegetable, tomatoes technically are a fruit because they develop from a flower. Squash, cucumbers, and eggplants also develop from a single ovary and are classified botanically as fruits.
All the living organisms including plants and animals have the capability to produce new individuals during their lifespan. This process of producing a new organism from the existing organism (or the parent) of the same species is called reproduction. The new individuals produced, are the copies of their parents. The process of reproduction is one of the important life processes and is essential for the continuity of the species.
The parts of a plant that participate in the process of sexual reproduction are called reproductive parts or organs. In plants, the reproductive parts are a flower which may have the male or female part or both the parts on the same flower.
Different organisms reproduce in a different way. In plants, there are two different methods of reproduction:
Asexual Reproduction
The process in which only one parent is involved in the production of new individuals of the same kind is called asexual reproduction. In plants, asexual reproduction results in the formation of offsprings or new plants without seeds or spores.
Asexual reproduction in plants occurs through the following methods:
1. Vegetative Propagation
It is the formation of new plants from vegetative units of bud, stem, etc. These vegetative units are called propagules. Vegetative reproduction may take place using various plant parts as given below:
(ii) Another method of vegetative reproduction in stem is by layering. In this method, a mature branch of parent plant is bent down and covered with soil. The tip of the plant is kept above the ground. The root develops from the branches and grows into a new plant. Layering method is usually done in the plants that have long and slender branches, e.g. jasmine.
(iii) Grafting is also a method of vegetative reproduction in stems, where new plants of desired qualities is developed from two different plants. The part that has shoot part is called scion and part having root is called stock. Scion is attached to the stock which provides support and basic requirement for the development of plant, e.g. apple, mango, rose, etc.
Sexual Reproduction
Flowers are the reproductive part of a plant. They help the plants in sexual reproduction and producing fruits and seeds. In sexual reproduction, a male cell is produced by the male part of a flower which fuses with a female cell produced by the female part of the flower. These cells are called gametes, which when combined form a zygote by the process called fertilisation.
Sexual reproduction is a way of making a new individual by joining two special sex cells, called gametes. In the sexual reproduction of animals and plants, the male and female gametes join to form a single fertilised cell called a zygote, which develops into a new individual with a unique collection of genetic material. In a population, this genetic variation is important because, if conditions become hard, there is a chance that some individuals will survive.
Pollination is a very important part of the life cycle of a flowering plant. It is part of the sexual reproduction process of flowering plants, which results in seeds that will grow into new plants. Flowers are the structures of flowering plants that contain all the specialised parts needed for sexual reproduction.
Did you know that plants can grow and reproduce without seeds or spores? Vegetative propagation is a process in which plants reproduce from stems, roots and leaves. It is a form of asexual reproduction seen in plants. In fact, horticulturists use propagation methods such as grafting and budding to improve the plants. Let us learn more about vegetative propagation.
Answer: The asexual reproduction where the vegetative part of the plant which give rise to a new plant is known as vegetative reproduction. Ginger is propagated by the rhizome. Chrysanthemum is propagated by stem cutting. Roots are used in vegetative propagation of sweet potato. The roots bear adventitious buds from which new plants can develop when it is buried in the moist soil. Such roots are called reproductive roots. Potato is propagated by eye of tuber.
So, the correct answer is option C.
Answer: Begonia and Bryophyllum are examples of vegetative propagation by leaves.
This is a form of asexual reproduction in which new plants grow from the buds growing on the margin of the leaves. These buds are reproductive in nature and when they fall on the ground they germinate and form a new plant.
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In case of plants, the requirement of two parents is not always necessary for reproduction. Many plants reproduce by asexual methods such as budding, fragmentation and spore formation. These methods do not require two parents.
The artificial methods that are used to carry out reproduction in plants without any utilisation of reproductive organs is called artificial propagation. Some examples of artificial propagation are as follows:
1. Grafting: The process of grafting involves tying a bud or twig of a plant (scion) over the stem that has been cut from another plant (stock).
2. Layering: In this process, a relatively younger branch is bent and layered with moist soil. This layered branch later develops its own root system and grows into a new plant.