Short Answer Questions
1. What are the different phases in the life cycle of an organism?
Answer:
The life cycle of an organism consists of three main phases: Juvenile phase (growth period before reproductive maturity), Reproductive phase (when the organism can reproduce), and Senescent phase (aging period before death).
2. How does reproduction ensure continuity of life?
Answer:
Reproduction allows organisms to pass their genetic material to the next generation, ensuring the survival and evolution of species over time.
3. Explain the difference between external and internal fertilization.
Answer:
In external fertilization, gametes fuse outside the female body (e.g., fish, amphibians). In internal fertilization, fertilization occurs inside the female body, providing better protection and development for the embryo (e.g., mammals, birds).
4. What is vegetative propagation? Give two examples.
Answer:
Vegetative propagation is a type of asexual reproduction in plants where new plants develop from vegetative parts like roots, stems, or leaves. Examples: Potato (tuber), Bryophyllum (leaf buds).
5. How does reproduction in unicellular organisms differ from that in multicellular organisms?
Answer:
In unicellular organisms, reproduction occurs through simple processes like binary fission or budding, producing identical offspring. In multicellular organisms, reproduction is more complex and can be either asexual (e.g., fragmentation in Spirogyra) or sexual (e.g., internal fertilization in humans).
6. Why is sexual reproduction considered advantageous over asexual reproduction?
Answer:
Sexual reproduction introduces genetic variation, which enhances adaptability, survival, and evolution, while asexual reproduction produces genetically identical offspring, limiting diversity.
7. Define senescence. What happens to an organism during this phase?
Answer:
Senescence is the final phase of an organism’s life cycle, marked by aging. During this phase, metabolic functions slow down, immunity weakens, and the organism becomes less capable of reproduction, eventually leading to death.