The eighth chapter in Science textbook is 'How do organisms reproduce?'
Organisms reproduce in two ways- asexually and sexually. Asexual reproduction does not involve the fusion of male and female gametes. This takes place in bacteria, amoeba, hydra, etc. Sexual reproduction involves the fusion of male and female gametes and can be seen in humans and many animals.
Organisms reproduce in two ways- asexually and sexually. Asexual reproduction does not involve the fusion of male and female gametes. This takes place in bacteria, amoeba, hydra, etc. Sexual reproduction involves the fusion of male and female gametes and can be seen in humans and many animals.
Asexual Reproduction
It involves only one parent.
There is no formation and fusion of gametes.
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The young ones formed are almost identical to each other as well as to the parent cell. Asexual reproduction generally occurs during favourable environmental conditions and when there is an abundance of food. It is a faster method of reproduction.
Sexual Reproduction
The mode of reproduction that takes place with the involvement of two individuals of two different sexes i.e.
male and female.
During sexual reproduction, male organism having male sex organs produces male gametes i.e.
sperms which are small and motile and the female organism having female sex organs produces ova which are generally large and store food.
Male and female gametes fuse to form a zygote that grows into a new organism.
The topics discussed in this chapter are as follows:
- Forms of Asexual Reproduction
- Sexual Reproduction in Plants and Humans
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NCERT Solutions for Chapter 8: How do organisms reproduce?
Also Check
Chapter 1: Chemical Reactions and Equations
Chapter 2: Acids, Bases and Salts
Chapter 3: Metals and Non-Metals
Chapter 4: Carbon and its compounds
Chapter 5: Periodic Classification of Elements
Chapter 6: Life Processes
Chapter 7: Control and Coordination
Chapter 9: Heredity and Evolution
Chapter 10: Light - Reflection and Refraction
Chapter 11: The Human Eye and the Colourful World
Chapter 12: Electricity
Chapter 13: Magnetic Effects of Electric Current
Chapter 14: Sources of Energy
Chapter 15: Our Environment
Chapter 16: Sustainable Management of Natural Resources
Check out Frequently Asked Questions (FAQs) for Chapter 8: How do organisms reproduce?
Define menopause.
At the age of around 45-50 years, the ovaries of the females stop producing ova. The stoppage of menstrual flow and other events like the changes in the hormonal composition is known as menopause.
Describe asexual reproduction in amoeba.
Amoeba reproduces by the process of binary fission. During this process, the nucleus divides first, followed by the formation of a constriction in the cellular membrane of amoeba. This gradually increases inwards and divides the cytoplasm into two parts. Finally two daughter organisms are obtained.
What is pollination? Describe cross-pollination.
The transfer of pollen grains from anther to stigma is called pollination. Pollen grains are shed from the anther and reach the stigma of either the same flower or a different flower.
Cross-pollination
The transfer of pollen grains from the anther of one flower to the stigma of another flower of the same species is termed as cross-pollination.What is ovulation?
The ovarian follicles present inside the ovaries develop into mature follicles. Usually, one mature ovarian follicle develops into a mature ovum. It pinches off from the surface of the ovary and enters the fallopian tube. This process is termed as ovulation. Generally ovulation takes place in only one ovary at a time.
Mention the modes of reproduction used by planaria.
Regeneration
