Extra Questions for Class 10 Science Chapter 9 Heredity and Evolution

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Q.1. Name the plant Mendel selected for his experiments on genetics.
Answer: The plant selected by Mendel for his experiments on Genetics was Pisum sativum. The common name for this plant is sweet pea.

Q.2. State the unit of hereditary material found in all living organisms.
Answer: The unit of hereditary material found in all living organisms is gene; Genes are the proteinaceous part present on the DNA (deoxyribonucleic acid – genetic material) and codes for all the characters expressed in any living organism.

Q.3. What is meant by pair of contrasting characters?
Answer: The pea plant studied by the Mendel has two contrasting traits of each and every character. Tall and dwarf are two contrasting traits of the character plant size similarly purple and white colour of the flower are the contrasting traits of the character flower colour. There were total 7 pairs of contrasting traits given by Mendel in Pisum sativum.

Q.4. Explain the term genetic drift.
Answer: Genetic drift is a phenomenon more common in the small population which may lead to the accumulation of different changes which lead to the formation of different species.
The accidental survival of the beetles of one colour that changed the common characteristics of the resultant population So accidental change in the small population can change the frequency of some gene in the population example accidental red beetles get crushed by elephant while green survived led to genetic drift which change the colour of the population to green.

Q.5. What is meant by variations found in a population?
Answer: Genetic variations are the differences which are found in a population of sexually reproducing organisms. The degree by which the progeny differs from its parents generation is known as variation. These differences are caused when two sets of chromosome combined together to form a new set.

Q.6. How is variation brought in the progeny in the sexually reproducing organisms?
Answer: Progenies which are formed in sexually reproducing organisms by fertilisation of male & female gamete. As these gametes contains genetic information of two distinct individual organisms (one male & one female), their fertilisation will produce progenies with varied genome. This is how variations are produced in sexually reproducing organisms.

Q.7. What is the parameter which decides inheritance?
Answer: The process by which different characters are passed on from the parent to the progeny is known as inheritance.
The rule of inheritance of such traits in human being are related to the fact that both father and the mother contribute practically equal amounts of genetic material to the child. This means that each trait can be influenced by both paternal and maternal DNA. Thus, for each trait there will be two versions in each child

Q.8. Why do mice whose tails were surgically removed just after birth for generations, continue to produce mice with tails?
Answer: The mice even after the removal of the tail after the birth is an acquired rate but the tail in the mouse is an example of inherited trait which means that even after cutting the tail inherited trait cannot be removed thus the mice continue to produce mice with tails.

Q.9. Evolution indicates the forever evolving life on the Earth. Give a statement supporting the above claim.
Answer: Evolution is the process in all forms of life over generations and evolutionary occurs. Biological populations develop through genetic changes that correspond to changes in the organism observable traits.
Evolution indicates the forever evolving life on earth. Evolution assures the continuity of various species & organisms on earth.
The accumulation of variations over a period of time is evolution.
Example: In a field there are red and green beetle. The crows are flying over the field found red beetles in the field to be eaten which give green beetle an advantage over red beetles and more the proportions of green beetles in the population would be in the population will eventually results in evolution of species to fit the environment better.
Thus, Evolution indicates the forever evolving life on the earth

Q.10. State the basis of classification of the organisms.
Answer: Classification of organism is the arrangement of organisms into a series of group based on physiological, biochemical, anatomical or other relationships.
The more closely two species are related, the more characteristics they will have in common. And the more closely they are related the more recently they will have had their common ancestors.
There are various categories of classification. These are:- kingdom, phylum/division, class, order, genus, species.

Q.11. Where are genes located in an organism?
Answer: Genes are the smallest unit of inheritance. They contain the information which is required to express a particular trait. They are present on the chromosomes inside the nucleus of the cell.

Q.12. How variation in a population leads to a survival advantage?
Answer: Variation refers to the difference in the characteristic or traits among the individuals of a species.
Variation is beneficial to the species because:

It enables the organism to adapt themselves in changing environment.

It forms the basis of heredity.

It forms the raw materials for evolution and development of new species.
Thus accumulation of variations in a population led to population to adapt to the changes and the new needs. This provide survival advantage to the species

Q.13. Define evolution.
Answer: Evolution is the process by which newer types of organism are developed from the pre-existing ones through modification in them due to certain factors like environmental change.
Example: Humans evolved from the great apes.

Q.14. If your mother has pierced ears, will you inherit the trait? If not, why?
Answer: In India almost all the girls have their ears pierced still we never see any girl born with her ears pierced already. It happens because the piercing is done on the body of the organism and no effect is caused on the genetic material. The traits we inherit depends solely on the genetic material of the parents and not on the physical features. Piercing is an acquired trait, not inherited one.

Q.15. Describe the phenomenon of homology.
Answer: According to Darwin, more closely related species have evolved from a common ancestor. The characteristics and fundamentally similar structures suggest the possibility of a common ancestor.
Such a phenomenon of similarity of structures due to common ancestry is known as homology. Example the forelimbs of vertebrates.

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