10 questions ยท Form 5 Biology Bab 6: Sexual Reproduction in Flowering Plants
What ploidy level is the endosperm nucleus formed during double fertilization in flowering plants?
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. What ploidy level is the endosperm nucleus formed during double fertilization in flowering plants?
Answer: C
The triploid (3n) endosperm nucleus is formed when one haploid male gamete (n) fuses with two polar nuclei (2n) in the central cell.
2. How many haploid nuclei and distinct cells are present in a mature embryo sac prior to fertilization?
Answer: B
Three mitotic divisions of the functional megaspore produce 8 nuclei, which are organized into 7 cells (3 antipodals, 2 synergids, 1 egg cell, and 1 central cell with 2 polar nuclei).
3. Which of the following structures constitutes the female reproductive organ (gynoecium / pistil)?
Answer: B
The gynoecium (pistil/carpel) consists of the sticky stigma, elongated style, and basal ovary containing ovules.
4. Which enzyme group is secreted by the growing pollen tube tip to digest style tissues?
Answer: B
Pollen tubes secrete digestive enzymes like cellulase and pectinase to breakdown cell wall components (cellulose and pectin) in style tissues.
5. Which sequence correctly traces the path of male gametes from pollen germination to fertilization?
Answer: A
Pollen germinates on the stigma, grows down the style, enters the ovule via the micropyle, and enters the embryo sac.
6. Which structural component of a pollen grain consists of a tough, sculpted outer layer resistant to decay?
Answer: B
The exine is the tough, highly resistant outer wall composed of sporopollenin that protects pollen grains from harsh environmental conditions.
7. Through which microscopic pore in the ovule integuments does the pollen tube enter the embryo sac?
Answer: B
The micropyle is the small opening in the ovule's protective integuments through which the pollen tube enters.
8. What term describes the transfer of pollen grains from the anther of one flower to the stigma of a flower on a different plant of the same species?
Answer: B
Cross-pollination involves pollen transfer between flowers on different individual plants of the same species, increasing genetic variation.
9. Where are antipodal cells located within a mature embryo sac?
Answer: B
The three antipodal cells position themselves at the chalazal end (opposite the micropylar opening) of the mature embryo sac.
10. How many total nuclear mitotic divisions occur within the functional megaspore during embryo sac formation?
Answer: C
The functional megaspore undergoes three consecutive mitotic nuclear divisions without immediate cytokinesis, producing $23 = 8$ haploid nuclei.