Practice questions and explanations focused on sexual reproduction in flowering plants. Covers key concepts like pollination, fertilization, and seed development to aid student understanding.
1 MMC undergoes 1 meiotic division to produce 4 megaspores, of which only 1 is functional (monosporic development). Therefore, to get 100 functional megaspores, you need 100 MMCs undergoing 100 meiotic divisions.
Ref: Equation: 1 MMC -(Meiosis)-> 1 Functional Megaspore (+ 3 degenerated).
In the mature embryo sac prior to fertilization, the central cell contains two polar nuclei. While they may fuse just before fertilization to form a secondary nucleus (2n), the typical description of the mature sac characterizes the cell as having two polar nuclei (n+n).
Ref: Central part of the embryo sac showing two distinct polar nuclei.
Wind-pollinated (anemophilous) flowers do not need to attract animals, so they are not colorful and do not produce nectar. They have light pollen, exposed stamens, and feathery stigmas to catch airborne pollen.
Ref: Image of Corn (Maize) tassels and silk vs. a colorful Rose.
The mitotic divisions of the functional megaspore nucleus are strictly free nuclear, meaning nuclear division is not followed immediately by cell wall formation. Cell walls are laid down only after the 8-nucleate stage is reached, leading to the 7-celled organization.
Ref: Sequence showing 1 -> 2 -> 4 -> 8 nuclei stage before cell walls form.
Pollen can be stored for long periods in liquid nitrogen at -196°C. This process is known as cryopreservation and is used in pollen banks, similar to seed banks.
Ref: Image of Cryopreservation tanks.
Self-incompatibility is a genetic mechanism. It recognizes self-pollen (from the same plant) and inhibits pollen germination on the stigma or pollen tube growth in the style, thereby preventing fertilization.
Ref: Diagram showing pollen tubes arrested in the style due to incompatibility factors.
Emasculation is the removal of anthers. If the female parent produces unisexual (pistillate) flowers, there are no anthers to remove, so emasculation is unnecessary. The flower buds are bagged before opening.
Ref: Diagram of a female unisexual flower (pistillate) showing no anthers to remove.
The Hilum represents the junction between the ovule and the funicle. It appears as a scar on the seed where the funicle was attached.
Ref: Diagram of an ovule indicating the specific junction point (Hilum).
The Endothecium (the layer below the epidermis) develops fibrous bands of alpha-cellulose. These bands are hygroscopic and help in the dehiscence (splitting) of the anther when it dries up, releasing the pollen.
Ref: Microscopic view of the anther wall showing the alpha-cellulosic fibrous bands in the Endothecium.
Pollen grains are rich in nutrients. Consumption of pollen products (tablets/syrups) is claimed to increase vitality and enhance the performance of athletes and race horses.
Ref: Image of a commercial 'Bee Pollen' supplement bottle.
It is obligate because neither can complete their life cycle without the other. The moth deposits its eggs in the locule of the ovary and pollinates the flower. The larvae feed on some of the developing seeds as they grow.
Ref: Image of a Yucca moth depositing eggs in the ovary of a Yucca flower.
The Filiform Apparatus consists of finger-like projections at the micropylar end of the Synergids. Its primary function is to secrete chemical attractants to guide the entry of the pollen tube into the synergid.
Ref: Detailed view of the Egg Apparatus showing cellular thickenings at the micropylar tip.
