🌿 Concept - Double Fertilization 🌿
1. Double fertilization occurs in:
A) Gymnosperms
B) Angiosperms
C) Bryophytes
D) Pteridophytes
Answer: B) Angiosperms
Explanation: Double fertilization is unique to angiosperms, where one male gamete fuses with the egg cell and the other with the central cell.
2. The process of double fertilization was discovered by:
A) Strasburger
B) B. M. Johansen
C) Nawaschin
D) Hofmeister
Answer: C) Nawaschin
Explanation: Nawaschin (1898) discovered double fertilization in Lilium and Fritillaria.
3. In double fertilization, one male gamete fuses with:
A) Egg cell
B) Synergid
C) Central cell
D) Polar nuclei
Answer: A) Egg cell
Explanation: One sperm fuses with the egg cell to form the diploid zygote.
4. The second male gamete fuses with:
A) Egg cell
B) Central cell
C) Synergid
D) Antipodal
Answer: B) Central cell
Explanation: The second sperm fuses with the two polar nuclei in the central cell to form the triploid primary endosperm nucleus.
5. The product of the fusion of the sperm with the egg cell is called:
A) Endosperm
B) Zygote
C) Embryo sac
D) Polar nucleus
Answer: B) Zygote
Explanation: The zygote is formed by the fusion of one sperm and one egg cell.
6. The product of fusion of sperm with two polar nuclei is:
A) Diploid
B) Triploid
C) Tetraploid
D) Haploid
Answer: B) Triploid
Explanation: Fusion of a sperm (1n) with two polar nuclei (each 1n) forms a triploid (3n) primary endosperm nucleus.
7. Double fertilization ensures:
A) Formation of male gametes
B) Simultaneous formation of zygote and endosperm
C) Formation of pollen grains
D) Fertilization in gymnosperms
Answer: B) Simultaneous formation of zygote and endosperm
Explanation: Double fertilization allows zygote and endosperm to develop together, coordinating embryo nourishment.
8. Which structure in the embryo sac fuses with sperm during fertilization?
A) Synergid
B) Egg cell
C) Antipodal cell
D) Polar nuclei
Answer: B) Egg cell
Explanation: The egg cell receives one male gamete to form the zygote.
9. The second male gamete fuses with polar nuclei to produce:
A) Cotyledons
B) Primary endosperm nucleus
C) Embryo
D) Ovule
Answer: B) Primary endosperm nucleus
Explanation: Fusion of sperm with polar nuclei produces the primary endosperm nucleus (triploid), which develops into endosperm.
10. The number of male gametes involved in double fertilization:
A) 1
B) 2
C) 3
D) 4
Answer: B) 2
Explanation: Two male gametes are released from a pollen tube; one fuses with the egg, the other with polar nuclei.
11. The tube nucleus in pollen grain:
A) Divides into gametes
B) Forms pollen tube
C) Forms synergids
D) Forms antipodals
Answer: B) Forms pollen tube
Explanation: Tube nucleus guides the pollen tube toward the ovule.
12. The generative cell in pollen divides to form:
A) One sperm
B) Two sperm
C) Egg
D) Zygote
Answer: B) Two sperm
Explanation: The generative cell undergoes mitosis to produce two male gametes.
13. The structure that receives pollen during pollination is:
A) Ovule
B) Anther
C) Stigma
D) Style
Answer: C) Stigma
Explanation: Pollen lands on the stigma, germinates, and grows down the style.
14. In angiosperms, the female gametophyte is called:
A) Embryo
B) Embryo sac
C) Endosperm
D) Ovule
Answer: B) Embryo sac
Explanation: Female gametophyte, called embryo sac, develops inside the ovule.
15. The typical number of cells in a mature embryo sac is:
A) 4
B) 6
C) 7
D) 8
Answer: D) 8
Explanation: The Polygonum type embryo sac has 8 nuclei/cells (1 egg, 2 synergids, 3 antipodals, 2 polar nuclei).
16. Which cells guide the entry of pollen tube into the embryo sac?
A) Antipodal
B) Synergids
C) Polar nuclei
D) Egg cell
Answer: B) Synergids
Explanation: Synergids help in attracting and guiding the pollen tube.
17. In Polygonum type embryo sac, the number of polar nuclei is:
A) 1
B) 2
C) 3
D) 4
Answer: B) 2
Explanation: Two polar nuclei lie in the central cell and fuse with one sperm during double fertilization.
18. Which of the following is not part of the embryo sac?
A) Egg cell
B) Synergid
C) Generative cell
D) Antipodal cell
Answer: C) Generative cell
Explanation: Generative cell is part of pollen, not embryo sac.
19. The entry point of pollen tube in the embryo sac is called:
A) Micropyle
B) Chalaza
C) Funiculus
D) Hilum
Answer: A) Micropyle
Explanation: Pollen tube enters the embryo sac through micropyle.
20. The type of endosperm formed in most angiosperms is:
A) Diploid
B) Triploid
C) Haploid
D) Tetraploid
Answer: B) Triploid
Explanation: Fusion of sperm (1n) with two polar nuclei (1n + 1n) forms triploid (3n) endosperm.
21. The process by which sperm nucleus fuses with egg nucleus is called:
A) Karyogamy
B) Syngamy
C) Plasmogamy
D) Fertilization
Answer: D) Fertilization
Explanation: Fertilization involves fusion of male and female gametes.
22. The fusion of sperm with egg nucleus is called:
A) Triple fusion
B) Syngamy
C) Autogamy
D) Pollination
Answer: B) Syngamy
Explanation: Syngamy refers specifically to fusion of gamete nuclei (zygote formation).
23. Fusion of sperm with polar nuclei is called:
A) Syngamy
B) Triple fusion
C) Autogamy
D) Fertilization
Answer: B) Triple fusion
Explanation: Fusion of sperm with two polar nuclei produces triploid primary endosperm nucleus → called triple fusion.
24. Double fertilization ensures synchronization between:
A) Embryo and pollen formation
B) Embryo and endosperm formation
C) Ovule and seed coat formation
D) Pollen and ovule maturation
Answer: B) Embryo and endosperm formation
Explanation: Double fertilization ensures that endosperm forms only when zygote is formed.
25. The process of pollen tube entry and sperm release is called:
A) Fertilization
B) Pollination
C) Pollen germination
D) Syngamy
Answer: C) Pollen germination
Explanation: Pollen germinates on stigma, forms tube, delivers sperm to embryo sac.
26. In angiosperms, fertilization occurs in:
A) Ovary
B) Ovule
C) Style
D) Stigma
Answer: B) Ovule
Explanation: Fertilization occurs inside the embryo sac within ovule.
27. The primary endosperm nucleus develops into:
A) Embryo
B) Endosperm tissue
C) Seed coat
D) Pollen grain
Answer: B) Endosperm tissue
Explanation: The triploid nucleus undergoes mitosis to form endosperm.
28. The zygote develops into:
A) Endosperm
B) Embryo
C) Cotyledon
D) Seed coat
Answer: B) Embryo
Explanation: The zygote undergoes divisions and differentiation to form the embryo.
29. The nutritive tissue for embryo in angiosperms is:
A) Zygote
B) Endosperm
C) Cotyledon
D) Ovule
Answer: B) Endosperm
Explanation: Endosperm provides nutrition for embryo development.
30. The male gametes are formed inside:
A) Ovule
B) Anther
C) Ovary
D) Style
Answer: B) Anther
Explanation: Male gametes develop inside pollen grains in anther.
31. The common type of embryo sac in angiosperms is:
A) Fritillaria type
B) Allium type
C) Polygonum type
D) Oenothera type
Answer: C) Polygonum type
Explanation: Polygonum type (8-nucleate) is the most common.
32. In gymnosperms, double fertilization is:
A) Common
B) Absent
C) Same as angiosperms
D) Partial
Answer: B) Absent
Explanation: Double fertilization is absent in gymnosperms.
33. In some plants like Plumbago, endosperm is:
A) Diploid
B) Triploid
C) Haploid
D) Tetraploid
Answer: A) Diploid
Explanation: Exception: In some species, endosperm forms from fusion of sperm with one polar nucleus only → diploid.
34. Fusion of sperm with synergid occurs in:
A) Angiosperms
B) Gymnosperms
C) Bryophytes
D) None
Answer: D) None
Explanation: Sperm never fuses with synergid; synergids guide pollen tube.
35. Triple fusion results in:
A) Diploid zygote
B) Triploid primary endosperm nucleus
C) Haploid embryo
D) Diploid endosperm
Answer: B) Triploid primary endosperm nucleus
Explanation: One sperm + 2 polar nuclei = 3n endosperm.
36. The type of fertilization where one sperm fuses with egg and the other degenerates is called:
A) Single fertilization
B) Double fertilization
C) Autogamy
D) Cross fertilization
Answer: A) Single fertilization
Explanation: In single fertilization, only zygote is formed; endosperm may form without fertilization (e.g., apomixis).
37. In which type of endosperm formation, fertilization is not required?
A) Nuclear
B) Cellular
C) Helobial
D) Autonomous
Answer: D) Autonomous
Explanation: In autonomous endosperm formation, endosperm develops without fertilization.
38. The process of double fertilization prevents:
A) Wastage of nutrients
B) Zygote formation
C) Pollen formation
D) Seed coat formation
Answer: A) Wastage of nutrients
Explanation: Endosperm develops only if zygote forms → efficient resource use.
39. In monocots like Zea mays, double fertilization results in:
A) Diploid endosperm
B) Triploid endosperm
C) No endosperm
D) Diploid zygote only
Answer: B) Triploid endosperm
Explanation: Typical in monocots, triploid endosperm nourishes embryo.
40. The egg cell is located:
A) At micropylar end
B) At chalazal end
C) Near polar nuclei
D) At funiculus
Answer: A) At micropylar end
Explanation: Egg cell lies near micropylar end, next to synergids.
41. The number of nuclei involved in triple fusion is:
A) 2
B) 3
C) 4
D) 5
Answer: B) 3
Explanation: Two polar nuclei + one sperm nucleus = 3 nuclei involved.
42. Double fertilization is advantageous because:
A) Embryo grows before pollination
B) Endosperm develops only if zygote is formed
C) Male gametes are wasted
D) Pollen tube grows faster
Answer: B) Endosperm develops only if zygote is formed
Explanation: Synchronizes embryo and endosperm development.
43. In Polygonum type embryo sac, number of synergids:
A) 1
B) 2
C) 3
D) 4
Answer: B) 2
Explanation: Two synergids are present at micropylar end.
44. Number of antipodal cells in Polygonum type embryo sac:
A) 1
B) 2
C) 3
D) 4
Answer: C) 3
Explanation: Three antipodal cells lie at chalazal end.
45. Male gametes are released in embryo sac by:
A) Syngamy
B) Pollen tube discharge
C) Triple fusion
D) Germination
Answer: B) Pollen tube discharge
Explanation: Pollen tube releases two sperm near egg and polar nuclei.
46. Double fertilization ensures:
A) Only zygote formation
B) Only endosperm formation
C) Formation of both zygote and endosperm
D) Fertilization in gymnosperms
Answer: C) Formation of both zygote and endosperm
Explanation: Ensures nutrition for the developing embryo.
47. Polar nuclei fuse with sperm during:
A) Syngamy
B) Triple fusion
C) Germination
D) Pollination
Answer: B) Triple fusion
Explanation: Fusion of sperm with 2 polar nuclei = triple fusion → 3n endosperm.
48. Fertilization in angiosperms is:
A) Internal and double
B) External and single
C) Internal and single
D) External and double
Answer: A) Internal and double
Explanation: Occurs inside ovule; involves zygote and endosperm formation.
49. Which part degenerates after fertilization in the embryo sac?
A) Synergids
B) Egg cell
C) Antipodal cells
D) Polar nuclei
Answer: A) Synergids
Explanation: Synergids degenerate after guiding pollen tube; fertilization completed.
50. The process of double fertilization is significant for:
A) Pollen dispersal
B) Efficient use of resources and embryo nourishment
C) Seed coat development
D) Pollination
Answer: B) Efficient use of resources and embryo nourishment
Explanation: Ensures that endosperm forms only if embryo is formed, conserving plant resources.
