Post-Fertilisation Events - Embryo and Seed - UNSOLVED PRACTICE SET
Chapter: Reproduction in Organisms | Topic: Post Fertilisation Events Embryo and Seed
POST-FERTILISATION EVENTS - EMBRYO AND SEED - UNSOLVED PRACTICE SET
Topic: Post Fertilisation Events Embryo and Seed
Multiple Choice Questions
Q1. The process of development of the embryo from the zygote is called:
- Gametogenesis
- Embryogenesis
- Fertilisation
- Parthenogenesis
Q2. In flowering plants, the endosperm is formed as a result of:
- Fusion of the egg cell with one sperm
- Fusion of the two polar nuclei with the second sperm (triple fusion)
- Fusion of two egg cells
- Division of the zygote
Q3. The zygote in animals undergoes repeated mitotic divisions called:
- Meiosis
- Cleavage
- Budding
- Fragmentation
Q4. In a typical dicot seed, the embryo consists of:
- Only the radicle
- Two cotyledons, a plumule, and a radicle
- Only the endosperm
- The seed coat only
Q5. The seed coat is formed from:
- The zygote
- The integuments of the ovule
- The endosperm
- The embryo sac
Short Answer Questions
Q6. What is embryogenesis? Describe the main stages of embryonic development in animals from zygote to gastrula.
Q7. Differentiate between a zygote and an embryo. At what stage does the zygote become an embryo in humans?
Q8. Explain the formation of the endosperm in flowering plants. Why is the endosperm important for the developing embryo?
Q9. A student examines a bean seed and a maize grain. How can she distinguish between a dicot seed and a monocot seed by simple observation? Mention two visible differences.
Long Answer Questions
Q10. Explain post-fertilisation events in flowering plants. Describe the development of the endosperm (triploid, nutritive tissue), the development of the embryo (globular, heart-shaped, mature embryo with radicle, plumule, and cotyledons), the formation of the seed from the ovule, and the formation of the fruit from the ovary. Why is the seed considered a remarkable evolutionary innovation?
Q11. "The seed is a baby plant in a box with its lunch packed inside." Analyse this analogy by explaining: the structure of a typical dicot seed (seed coat, cotyledons, embryo axis), the role of the endosperm (or cotyledons in non-endospermic seeds) as stored food, the protective function of the seed coat, and the adaptive significance of seed dormancy and dispersal mechanisms for survival and colonisation of new habitats.
APPLICATION / ANALYSIS
Q12. Case Study — Seed Development Comparison:
A botanist studied seed development in two plants:
| Feature | Plant X (Bean) | Plant Y (Maize) |
|---|---|---|
| Cotyledons | 2 | 1 |
| Endosperm in mature seed | Absent (used up during development) | Present (large, starchy) |
| Seed type | Non-endospermic | Endospermic |
| Food storage site | Cotyledons | Endosperm |
| Germination pattern | Epigeal (cotyledons come above ground) | Hypogeal (cotyledon stays below) |
Answer the following:
(a) Why does Plant X use up its endosperm during development while Plant Y retains it? Explain the different strategies of food storage.
(b) A gardener plants both seeds at 5 cm depth. Which seedling is more likely to successfully emerge, and why? Consider the energy reserves available.
(c) If a mutation prevents endosperm formation in Plant Y, would the embryo survive? Explain your answer.
Q13. Real-Life Application — Seed Bank Conservation:
The National Bureau of Plant Genetic Resources (NBPGR) in New Delhi maintains a seed bank with over 4 lakh samples:
Storage conditions:
- Temperature: -18°C to -20°C
- Humidity: Very low (15-20%)
- Seeds sealed in moisture-proof containers
- Some seeds tested for viability every 10 years
Answer the following:
(a) Why are seeds stored at very low temperatures and low humidity? Explain the biological basis in terms of embryo metabolism.
(b) Why must seeds be tested for viability periodically? What cellular process might gradually reduce viability even in perfect storage conditions?
(c) Some seeds, like those of coconut and mango, cannot be stored dry and cold. These are called "recalcitrant seeds." Why do you think they cannot survive drying, and what alternative conservation method might be used?