1. What is Reproduction?

How do organisms reproduce

Sample question paper

• What is difference between sexual reproduction and asexual reproduction
• What is difference between binary fission and multiple fission
• Explain the binary fission in case of amoeba
• What do you mean by vegetative propagation and what are its advantages
• Define grafting
• What are artificial methods of reproduction what is the difference between cutting and layering
• What do you mean by pollination what are the two different types of pollination explain them along with figure
• What do you mean by fertilization
• What are four different parts of the flower explain all of them along with their function
• What is the other name of female part of a flower
• What are angiosperm flowers

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Chapter 8

How do organisms reproduce?

Reproduction: It is the process by which living organisms produce new individuals similar to themselves.

• Reproduction ensured continuity of life on earth.
• It is a bridge to hereditary transmission.
• It involves a continuation of characters from the parents to daughter cells by copying of DNA (Deoxyribose Nucleic Acid) molecules present in the chromosomes of the cell.
• Copying of DNAs is also not a fool proof exercise, even minute changes bring about variation in the blue print of the off springs.
• The useful variations are retained while the harmful ones do not go beyond.
• Actually, variations help the species to withstand drastic environmental changes, thus save the species from becoming extinct and promotes its survival for a longer time.
• This inbuilt tendency of variation is the “basis” for Evolution.

Sexual Reproduction: When reproduction takes place as a result of the fusion between two gametes, one from each parent, it is called sexual reproduction.

• This process of fusion between two gametes is called fertilization.
• The formation of gametes involves an exchange of chromosomal (genetic) fragments between homologous chromosomes causing genetic recombination which leads to variation.

Asexual Reproduction

• It involves only one parent.
• There is no formation and fusion of gametes. 
• The young ones formed are almost identical to each other as well as to the parent cell. 
• Asexual reproduction generally occurs during favorable environmental conditions and when there is an abundance of food.
• It is a faster method of reproduction.

Importance of variation
Using the ability to reproduce, living organisms increase their population and feed on available resources in their niche. Changes in DNA and body design may result in difficulty to sustain themselves in their habitat. But we know that the environment is not consistent. It changes with the change in different factors like climate, temperature, availability of resources, etc. During these environmental changes, if a particular species is too adamant to change, it can’t survive in that habitat. Here comes the role of variation. Variations in species help them to adapt themselves to that particular environment and give them a chance of survival.