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Class ten Heredity and Evolution Additional Question

Chapter 9: Heredity and Evolution

Topic 1: Heredity and Variation

Very Short Answer Type Questions [1 Mark]

Q.1. What is heredity?

Ans. Transmission of characters or traits from parents to offspring through their genes is called heredity.

Q.2. What is inheritance?

Ans. The mechanism by which transmission of genetically controlled traits or characteristics takes place from one generation to the next is known as inheritance.

Q.3. Define genetics.

Ans. The branch of science dealing with the heredity and variation in living organisms is called genetics.

Q.4. Give the scientific name of the plant on which Mendel experimented.

Ans. Scientific name of garden pea : Pisum sativum.

Q.5. How many chromosomes are present in human beings?

Ans. 46 chromosomes or 23 pairs.

Q.6. Define a monohybrid cross.

Ans. The cross involving the inheritance of only one pair of contrasting characteristics is called a monohybrid cross.

Q.7. Give the gene complement of women with ‘O’ blood group.

Ans. I°I° or ii

Q.8. Define a dihybrid cross.

Ans. The cross involving the inheritance of only two pairs of contrasting characteristics is called a dihybrid cross.

Q.9. State the name of chemical of which chromosomes are made.

Ans. DNA (Deoxyribonucleic acid)

Topic 2: Evolution and Speciation

Very Short Answer Type Questions [1 Mark]

Q.1. Define evolution.

Ans. The gradual change in inherited traits of a population over a period of time is known as evolution.

Q.2. Define mutation.

Ans. Sudden changes in the structure of genes of chromosome or change in a number of chromosomes are called a mutation.

Q.3. What is meant by speciation?

Ans. The process of development of new species from the existing species is called speciation.

Q.4. Name two methods to determine the age of fossils.

Ans. (i) Radioactive method

(ii) Carbon dating method

Q.5. What is genetic drift?

Ans. Flow or migration of one gene pool from a population that occurs by chance is called genetic drift.

Q.6. Give one example of an acquired trait in humans.

Ans. Development of muscular body.

Q.7. How birds are related to dinosaurs?

Ans. Birds are very closely related to reptiles, as dinosaurs are reptiles and both birds and dinosaurs have feathers.

Q.8. What is the evolutionary significance of the fossil Archaeopteryx?

Ans. It is the connecting link between reptiles and birds. It has both reptilian and avian (bird) features.

Q.9. How was Earth’s atmosphere, millions of years ago?

Ans. Millions of years ago, the Earth was very hot and had inorganic substances around it such as methane, hydrogen, ammonia, etc.

Q.10. Name the scientists who experimentally proved that life arose from inorganic materials.

Ans. Miller and Urey.

Q.11. Define variations.

Ans. The differences in the characters or traits among the individuals, within a species or population are known as variations.

Q.12. Give one advantage of variations in living organisms.

Ans. Variations increase the chances of survival of living organisms in their particular environment.

 Topic 3 : Evolution by Stages

Very Short Answer Questions [1 Mark]

Q.1. Define artificial selection.

Ans. It refers to the selection of desirable characters from one organism manually or artificially and recombining them in another organism for the production of useful varieties of plants and animals.

Q.2. What do you understand by molecular phylogeny?

Ans. The study of changes accumulated in DNA over generations and establishing a connection between organisms on the basis of these is called molecular phylogeny.