Q1. ‘A trait may be inherited, but may not be expressed’. Justify this statement with the help of a suitable example.
Q2. Define evolution. How does it occur? Describe, how fossils provide us evidences in support of evolution.
Q3. Name any five vegetables generated from a common ancestor through artificial selection rather than natural selection. Also mention the features for which each vegetable is selected?
Q4. Does geographical isolation of individuals of a species lead to formation of a new species? Provide a suitable explanation.
Q5. Why is it more appropriate to compare the process of evolution with’ branches of a tree rather than with a ladder?
Q6. How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?
Q7. (i) What is meant by traits of an individual?
(ii) Explain inherited trait and acquired trait.
(iii) Define speciation. List the factors which could lead to rise of a new species.
Q8. (i) Explain whether traits like eye colour or height is genetically inherited. Do power to lift weights and reading French also belong to the same category?
(ii) How do variations affect the evolution of those organisms that reproduce sexually?
Q9. Name the phenomenon that governs the following:
(i) Green beetles living in green bushes are not eaten by the crows.
(ii) Number of blue beetles in green bushes increases only because the red beetles, living there, were trampled by a herd of elephants.
(iii) No ‘medium height plants’ are obtained in F1 generation, upon crossing pure tall and dwarf pea plants.
(iv) Tails of mice were surgically removed for several generations, still mice had tails in the following generations.
(v) A migrant beetle reproduces with the local population; as a result, genes of migrant beetle enter the new population.
Q10. What are fossils? How are they formed? List two methods of determining the age of fossils. Explain in brief the importance of fossils in deciding the evolutionary relationships.
Q11. (a) What are fossils and how is age of fossils determined?
(b) During artificial selection, which features of wild cabbage were selected to give rise to
(i) Cabbage and
Q12. Ovum and sperm are both female and male gametes, respectively. But what is so intricate in sperm which makes it solely responsible for determining the sex of the child? Explain.
Q13. Define the following.
(c) Recessive trait
(b) Genetic drift
Q14. How does comparing DNA of different species help in tracing evolutionary relationship?