Flower structure, male and female gametophytes
- How many meiotic and mitotic divisions need to occur for the development of a mature female gametophyte from the megaspore mother cell in an angiosperm plant? Answer: 3. 1 Meiosis and 3 Mitosis Key idea: Count divisions from megaspore mother cell (MMC) to the 7-celled, 8-nucleate embryo sac. MMC un... 1
- Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.Reason (R) : Presence of more than one nuc… Answer: 1. Both A and R are true and R is the correct explanation of A Key idea: The tapetum is the innermost wall layer of the anther and n... 1
- Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : A typical unfertilised, angiosperm embryo sac at maturity is 8 nucleate and 7-celled.Reason (R) : The egg apparatus has 2 polar… Answer: 3. A is true but R is false Key idea: The mature embryo sac is 7-celled and 8-nucleate, so A is true. The reason is false: the egg a... 1
- Identify the correct description about the given figure: Answer: 2. Wind pollinated plant inflorescence showing flowers with well exposed stamens. Key idea: a dense spike with many long, well-expos... 1
- A typical angiosperm embryo sac at maturity is : Answer: 1. 8-nucleate and 7-celled A typical (Polygonum-type) embryo sac forms from the megaspore by three mitotic divisions, giving 8 nucle... 1
- The body of the ovule is fused within the funicle at : Answer: 1. Hilum The ovule is attached to the funicle (stalk) at the hilum, where the body of the ovule fuses with the funicle. The micropyl... 1
- The plant parts which consist of two generations - one within the other :(a) Pollen grains inside the anther(b) Germinated pollen grain with two male gametes(c) Seed inside the fruit(d) Embryo sac inside the ovule Answer: 4. (a) and (d) Key idea: Two generations one inside the other means a gametophyte developing inside a sporophyte structure, i.e., a... 1
- Pollen grains can be stored for several years in liquid nitrogen having a temperature of Answer: 2. – 196°C Pollen can be cryopreserved in liquid nitrogen at -196^° C for years. The other temperatures are not that of liquid nitro... 1
- Which of the following flowers only once in its life-time ? Answer: 1. Bamboo species Some plants are monocarpic and flower only once in life; bamboo flowers once after about 50 to 100 years and then... 1
- Which of the following has proved helpful in preserving pollen as fossils ? Answer: 4. Sporopollenin Sporopollenin, the material of the pollen exine, is extremely resistant to heat, acids, alkalis and enzymes. So the... 1
- Functional megaspore in an angiosperm develops into : Answer: 2. Embryo sac The functional megaspore divides mitotically to form the female gametophyte, the embryo sac. Endosperm and embryo form... 1
- In majority of angiosperms Answer: 2. reduction division occurs in the megaspore mother cells In most angiosperms the megaspore mother cell (2n) divides by meiosis (re... 1
- The ovule of an angiosperm is technically equivalent to Answer: 4. megasporangium The ovule is the structure in which the megaspore mother cell and then the embryo sac form. It is therefore equiva... 1
- Which one of the following statements is not true ? Answer: 1. Tapetum helps in the dehiscence of anther The tapetum nourishes the developing pollen grains; it does not help in anther dehiscen... 1