Module: | Pollination & Outbreeding Devices
Q58: Consider the following statements regarding the specific mechanisms of apospory and diplospory:
1. In apospory, a diploid somatic cell of the nucellus or integument undergoes mitotic divisions to develop directly into an unreduced embryo sac.
2. In diplospory, the megaspore mother cell (MMC) bypasses the meiotic reduction division entirely and directly gives rise to a diploid embryo sac.
3. Because both apospory and diplospory involve the formation of an embryo sac, they are strictly classified as forms of normal sexual reproduction.
Which of the above statements is/are correct?
2. In diplospory, the megaspore mother cell (MMC) bypasses the meiotic reduction division entirely and directly gives rise to a diploid embryo sac.
3. Because both apospory and diplospory involve the formation of an embryo sac, they are strictly classified as forms of normal sexual reproduction.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, but Statement 3 is fundamentally incorrect.
Apomixis is the biological bypass of sexual reproduction, producing seeds without fertilization.
The phenomenon is sub-categorized based on the exact structural origin of the unreduced (diploid) female gametophyte.
Apospory occurs when a standard somatic cell from the ovule (typically from the nucellus) acts as the starting point, completely ignoring the megaspore mother cell (MMC). Diplospory occurs when the MMC is activated but fails to undergo meiosis, dividing mitotically instead to form the diploid embryo sac.
Statement 3 fails the evolutionary definition test: although these processes mimic sexual reproduction by forming an embryo sac and eventually a seed, the absolute absence of meiosis and syngamy mathematically classifies both apospory and diplospory as obligate forms of asexual reproduction.
Apomixis is the biological bypass of sexual reproduction, producing seeds without fertilization.
The phenomenon is sub-categorized based on the exact structural origin of the unreduced (diploid) female gametophyte.
Apospory occurs when a standard somatic cell from the ovule (typically from the nucellus) acts as the starting point, completely ignoring the megaspore mother cell (MMC). Diplospory occurs when the MMC is activated but fails to undergo meiosis, dividing mitotically instead to form the diploid embryo sac.
Statement 3 fails the evolutionary definition test: although these processes mimic sexual reproduction by forming an embryo sac and eventually a seed, the absolute absence of meiosis and syngamy mathematically classifies both apospory and diplospory as obligate forms of asexual reproduction.