Plant Physiology and Reproduction

Phytochrome is a pigment found in plants that acts as a photoreceptor, not a hormone. GA3 (gibberellin), ethylene, and auxins are all well-known plant hormones.

Photoperiodism was first discovered by Garner and Allard in 1920 using a variety of tobacco called Maryland Mammoth.

The term vernalization, which refers to the induction of flowering by exposure to prolonged cold, was coined by the Russian scientist T.D. Lysenko.

Vernalization involves exposing seeds to low temperatures, typically in the range of 0 to 5 degrees Celsius, to promote flowering.

NAA (Naphthaleneacetic acid) is a synthetic auxin used to prevent premature fruit drop and promote fruit thinning.

A phytotron is a specialized laboratory or facility where plants are grown under strictly controlled environmental conditions, such as light, temperature, and humidity.

Cytokinins are plant hormones that promote cell division and are essential for inducing shoot formation (morphogenesis) in plant tissue culture.

White light contains the full spectrum of wavelengths necessary for photosynthesis and optimal plant growth.

Auxin transport in plants is polar, specifically moving from the shoot tip downwards toward the roots, which is known as basipetal transport.

Day-neutral plants flower regardless of the day length. Tomato is a classic example of a day-neutral plant.

Meiosis is a reduction division where the chromosome number is halved. If the mother cell has 40 chromosomes, the resulting cells will have 20 chromosomes each.

Meiosis occurs in the megaspore mother cell (MMC) within the nucellus to produce haploid megaspores. The nucellus is the tissue containing the MMC, but the division itself happens specifically in the MMC.

In angiosperms, the pollen grain contains a generative cell and a tube cell. The generative cell undergoes mitosis to produce two male gametes.

The Polygonum type of embryo sac is the most common type in angiosperms. It develops from a single megaspore (monosporic) and undergoes three rounds of mitosis to form eight nuclei.

Since the pollen comes from the same plant, the genetic makeup is identical, making it genetically self-pollination. However, because it involves the transfer of pollen between two different flowers, it is ecologically cross-pollination (geitonogamy).

 Movement of curvature is due to growth movement.
Movement of locomotion is due to tactic movement.
Movement of variation is due to turgor pressure.

Synergids are part of the egg apparatus within the embryo sac. Like all cells in the mature embryo sac, they are haploid.

Flowers pollinated by insects (entomophily) need to ensure pollen adheres to the insect body. Sticky and rough pollen grains are well-adapted for this purpose.

Xenia refers to the effect of foreign pollen on the tissues of the seed, specifically the endosperm, resulting in changes to its color or composition.

Vallisneria is a classic example of hydrophily (pollination by water). The male flowers are released into the water and float to reach the female flowers.

Salvia flowers have a specialized lever mechanism where an insect entering the flower pushes a sterile stamen arm, causing the fertile anther to deposit pollen on its back.

Parthenocarpy is the development of fruit without fertilization, resulting in seedless fruits. Parthenogenesis refers to embryo development without fertilization.

In a standard sigmoid growth curve, the exponential phase (or log phase) is characterized by the most rapid rate of growth.

Garner and Allard are famous for their pioneering research on photoperiodism, which is the physiological response of organisms to the length of day or night.

The growth of the pollen tube toward the ovule is directed by chemical signals released by the synergids, a process known as chemotropism.