Short Questions Answer
1. What is heredity?
Answer: Transmission of traits from parents to offspring is called heredity.
2. Who is known as the Father of Genetics?
Answer: Gregor Johann Mendel.
3. What are inherited traits?
Answer: Traits or characteristics passed from parents to offspring.
4. What is variation?
Answer: Differences between individuals of the same species.
5. Which type of reproduction causes more variation?
Answer: Sexual reproduction.
6. What are dominant traits?
Answer: Traits that express themselves even in the presence of a contrasting trait.
7. What are recessive traits?
Answer: Traits that are hidden or not expressed in the presence of a dominant trait.
8. What is a gene?
Answer: A section of DNA that controls a particular trait.
9. What are chromosomes?
Answer: Thread-like structures in the nucleus carrying genetic information.
10. Which chromosomes determine the sex of a child in humans?
Answer: Sex chromosomes (X and Y).
11. What is the sex chromosome pair in females?
Answer: XX.
12. What is the sex chromosome pair in males?
Answer: XY.
13. Who determines the sex of the child — mother or father?
Answer: Father (depending on whether he contributes X or Y chromosome).
14. What does the F1 generation represent?
Answer: The first filial generation produced after crossing two parent plants.
15. What does the F2 generation represent?
Answer: The second filial generation obtained by self-pollinating the F1 plants.
Long Questions Answer
1. Explain Mendel’s experiment on inheritance of one trait (monohybrid cross).
Answer: Mendel crossed a tall pea plant with a short one. In the F1 generation, all plants were tall, showing tallness as the dominant trait. In the F2 generation, the ratio of tall to short plants was 3:1, showing that traits are controlled by pairs of factors (genes), where one is dominant and the other is recessive.
2. Explain Mendel’s experiment on inheritance of two traits (dihybrid cross).
Answer: Mendel crossed pea plants having round-yellow seeds with wrinkled-green seeds. The F1 generation had all round-yellow seeds. The F2 generation showed a 9:3:3:1 ratio, proving that traits are inherited independently.
3. How does variation arise during reproduction?
Answer: During DNA copying, small errors or changes occur, and in sexual reproduction, the combination of genetic material from two parents produces greater variation.
4. How are traits expressed in organisms?
Answer: Genes in DNA provide information for making proteins that control specific traits, such as height or color, by affecting biochemical processes in the body.
5. Explain how the sex of a child is determined in humans.
Answer: Females have XX chromosomes and males have XY. The mother always gives an X, and the father gives either X (for a girl) or Y (for a boy). Thus, the father determines the sex of the child.
6. Why are variations important to a species?
Answer: Variations help some individuals survive environmental changes, promoting evolution and the survival of the species.
7. Differentiate between inherited and acquired traits.
Answer: Inherited traits are passed from parents (like eye color), while acquired traits develop due to environment or experience (like muscle strength) and are not inherited.
8. What are chromosomes and what role do they play in heredity?
Answer: Chromosomes carry genes, the units of heredity. They ensure genetic information is transferred from parents to offspring during reproduction.
9. What do you understand by the terms dominant and recessive traits? Give examples.
Answer: Dominant traits express themselves in the presence of a contrasting trait (e.g., tallness in peas), while recessive traits appear only when both genes are recessive (e.g., shortness in peas).
10. Explain the mechanism of equal genetic contribution from both parents in sexual reproduction.
Answer: Each parent contributes one set of chromosomes through gametes (egg and sperm). When they fuse, the offspring receives two sets—one from each parent—ensuring equal genetic contribution.
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