1. What is a gene? (1)
2. What is meant by analogous organs? Taking a suitable example, explain how they support the theory of Organic Evolution. (3)
3. The sex of the children is determined by what they inherit from their father and not their mother.” Justify. (3)
4. Distinguish between acquired and inherited traits by giving one example of each. Why are traits acquired during the lifetime of an individual not inherited? (3)
5. Explain the terms: (i) Speciation (ii) Natural selection (2)
6. A blue colour flower plant denoted by BB is cross bred with that of white colour flower plant denoted by bb.
(a) State the colour of flower you would expect in their F1 generation plants.
(b) What must be the percentage of white flower plants in F2 generation if flowers of F1 plants are self-pollinated?
(c) State the expected ratio of the genotypes BB and Bb in the F2 progeny. (5)
7. Define the term ‘evolution’. “Evolution cannot be equated with progress”. Justify this statement. (3)
8. If we cross pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F2 generation, then we obtain pea plants of F2 generation.
(a) What do the plants of F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation.
(c) State the type of plants not found in F2 generation but appeared in F2 generation, mentioning the reason for the same. (5)
9. How are fossils formed? Describe, in brief, two methods of determining the age of fossils. (3)
10. What are homologous organs? Can the wing of a butterfly and the wing of a bat be regarded as homologous? Why? (5)
Answers
Explanation:
1.Gene- gene is a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein.
2.Analogous organs are defined as the organs of different animals that are having different structure but perform the same functions.
3.Men determine the sex of a baby depending on whether their sperm is carrying an X or Y chromosome. An X chromosome combines with the mother's X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother's to make a boy (XY).
4.Acquired traits are the one that a person develops during his lifetime. These are not passed from one generation to another. On the other hand, inherited traits are present in the person since the time of his birth and are passed on from one generation to another.
5.(1)Speciation is the evolutionary process by which populations evolve to become distinct species.
(2)Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.