Botany and Plant Science

Etiolation is a condition in which plant is grown in the partial or complete absence of light. The leaves are tiny and yellow in color. Vernalization is the process by which plant can be induced to flower by exposing it to the prolonged cold or winter. It shortens the vegetative period and hastens the flowering. Photoperiodism is the phenomenon in which various physiological reactions like flowering response to the relative length of day and night.

Pseudo-embryo sacs, which are structures mimicking embryo sacs and functioning similarly without typical fertilization processes, are notably found in members of the family Podostemonaceae.

The first sign of geotropic response occurs at a short distance away from the apex except in monocots in which case it occurs at the nodes where meristems are formed. The bending of a plant organ in response to gravity is called as gravitropism or geotropism.  Geostimulation results in rapid and marked changes in the node-puvinus, internode and sheath. These changes involves water content, dry matter accumulation, endogenous gibberellic acids and GA4 metabolism.

Cambium is the layer which forms Cork and acts as a secondary meristem from a layer of collenchyma or parenchyma immediately beneath the epidermis. The cells which produce from cork cambium will differentiate and will get mature to perform a specialized function. The living cells which lost the capacity to divide can regain the capacity of the division under certain conditions is called as 'Dedifferentiation.'

 Xylem cells are dead and elongated hollow cells consists of secondary cell wall contains lignin.

If a plant is flashed with red light initially and then flashed with far red light, the effect of red light is reversed. It is due to the presence of phytochromes which are present in plants as the pigments for light absorption. It has two forms, Pr and Pfr. The range of absorption in wavelength is from 660 nm to 730 nm.

Photosynthesis requires light between 400 and 700 nm. Blue light promotes vegetative growth. Red and far-red promotes stem elongation. Red and blue light promotes flowering. Photoperiodism is best seen in red light as chlorophyll strongly absorbs red light and carries out photosynthesis. Hence, red light stimulates plant growth.

Pollenkitt is a sticky, oily coating found on the surface of insect-pollinated pollen grains. Besides lipids, it consists mainly of carotenoids, which give it its characteristic yellow or orange color and help protect against UV radiation.

The cells derived from root apical and shoot apical meristems and cambium differentiate and mature to perform specific functions. This process leading to maturation of cells is termed as differentiation. During differentiation, cells undergo few to major structural changes both in their cell walls and protoplasm e.g., to form a tracheary element the cells would lose their protoplasm, they also develop strong, elastic, lignocellulosic secondary cell walls, to carry water to long distances even under extreme tension. So, the correct answer is 'All of the above'.

Interfascicular cambium is the cambium formed by dedifferentiation of cells forming the ground tissue (parenchyma) that lie in line to the vascular cambium, since these strips of cambium originate between two vascular bundles or connect two vascular cambia together they are referred to as the interfascicular cambia. They are responsible for producing medullary rays during secondary growth.

Redifferentiation is the formation of new or differentiated tissue from a already differentiated tissue. During this process cells of parenchymatous tissue undergo dedifferentiation to meristematic tissue. The cells cut off by the meristematic tissue based on the location and function get modified to respective tissues like secondary cortex, secondary xylem and secondary phloem in roots, monocot stem, cork cells etc