Reproduction In Plants

BASIC SCIENCE JSS 2 THIRD TERM

Week 12

Topic: Reproduction in Plants

Introduction

Plant reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from the parent or parents. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other, except when mutations occur. All living things reproduce. Reproduction is the process of generating offspring.

Types of Reproduction

There are two main types of reproduction: sexual and asexual. Some organisms reproduce by only one type of reproduction and others can reproduce by both.

Asexual reproduction

The type of reproduction where cells from only one parent are used, is called asexual. Only genetically-identical organisms are produced by this type of reproduction.

Asexual reproduction in bacteria

Asexual reproduction is very common in microorganisms. Bacteria reproduce by binary fission. During binary fission, the cell divides into two daughter cells that are similar in size and shape.

Asexual reproduction in plants

Asexual reproduction in plants is also called vegetative reproduction. It usually involves only the plant’s vegetative structures like roots, stems and leaves. For example, raspberries can produce a new generation using their stems; potatoes, using their roots; and geraniums can be grown from any piece of a parent plant.

Sporulation

Some types of mould reproduce through sporulation. They produce reproductive cells – spores – that are stored in special spore cases until they are ready to be released. After they are released they will develop into new, individual organisms. Bread mould reproduces by sporulation.

Budding

During budding, a new organism starts growing from the parent’s body. At first it looks like a bud. This bud later develops into a mature organism. Sometimes it stays attached to the parent’s body and sometimes it breaks off. Hydras reproduce by budding.

Gemmules

Gemmules are special structures that are found in sea sponges. A parent sponge releases gemmules that later develop into mature sponges.

Regeneration

In the process of regeneration, detached pieces of the parent’s body can develop into a new organism if this body part contains enough genetic information. Some flat worms and starfish can reproduce by regeneration.

Advantages and disadvantages of asexual reproduction

• Asexual reproduction works well for organisms that stay in one place. Because they do not move, it is difficult for them to find a mating partner.
• Stable environments are the best places for organisms that reproduce asexually.
• Asexual reproduction is also much less time and energy consuming.
• Asexually-produced generation does not have any genetic variations. That means that these organisms will not have any ‘material’ for adapting to environmental changes. That is why many asexually-reproducing organisms can reproduce sexually as well.

Sexual Reproduction

During sexual reproduction, two gametes from both parents fuse, forming a zygote. A zygote is also referred to as a fertilised egg. All gametes are haploid cells, meaning they have only one set of chromosomes (1n). So, when gametes fuse, they form a diploid organism: 1n+1n=2n.

Sexual reproduction in algae

The simplest form of sexual reproduction in algae is conjugation, in which two similar organisms fuse, exchange genetic material and then break apart. Some multicellular green algae undergo a process called alternation of generations. During this process, generations of different types of organisms are produced: haploid and diploid. Haploid generation reproduces sexually. It is followed by diploid generation that reproduces asexually.

Sexual reproduction in flowering plants

Flowers contain both male and female parts. The female part is called the pistil, which consists of the ovary, ovule, style and stigma at the tip. Inside the ovary are the ovules. Each ovule contains an egg cell. The male structure is called the stamen. It consists of the filament and the pollen-producing anther. A new seed is formed when an egg cell joins with a pollen cell in the process of pollination. Pollination occurs when pollen grains are carried from the anther of the stamen to the stigma of the pistil.

Evaluation

1. There are two main types of reproduction, they are___
2. Define Regeneration?
3. What is the sexual part of flowering plants?
4. The female reproductive part of the plant is called ___
5. The male reproductive part of the flower is called the ___
6. Define asexual reproduction in plant
7. Explain budding.
8. Draw and label a flowering plant