Plant Transport and Physiology

Plants have photoreceptors, which are proteins that are specially designed to perceive light and signal certain biological effects in the plant. There are two types of photoreceptor proteins in plants - Phytochromes and Blue light receptors. Phytochromes absorb red light and far red light and help the plants to sense seasonal changes in night length, or photoperiod, thereby controlling the opening and closing of stomata.

When the leaf is exposed to light, the process of photosynthesis begins. As the photosynthetic reactions proceed in the guard cells, the residual carbon dioxide is converted to carbohydrates. The disappearance of carbon dioxide from the cytosol of the guard cell results in an increase in the cellular pH. 
As the pH rises, the activity of the enzymes, that convert starch and sugars to organic acids increases. The higher concentration of organic acids results in a higher concentration of hydrogen ions. The hydrogen ions of the guard cells are then exchanged for potassium ions in the subsidiary cells.
This increased concentration of potassium, combined with the higher levels of organic acids, lowers the osmotic potential of the guard cells, and, since water moves from regions of high osmotic potential to regions of lower osmotic potential, water will move from the subsidiary cells into the guard cells. This movement of water increases the turgor pressure (inner pressure) of the guard cells and causes them to swell. Thus, the stomata open.

The stomatal opening follows when solutes from near epidermal and mesophyll cell enter the guard cell lowering its osmotic potential and water potential. Also rising in K ions in guard cell allows movement of water into the guard cell from neighbouring cells and makes the guard cell swollen due to water accumulation which results in the opening of stomata. 

Guttation is loss of water in liquid form as a dilute solution from uninjured leaf tips. The uninjured leaf tips have hydathodes or water stomata. Under conditions of low transpiration dilute solution of minerals oozes out through them under the influence of increased root pressure.

Guttation is the excretion of drops of xylem sap on the tips or edges of leaves of some vascular plants through hydathode, such as grasses. It occurs in the absence of light i.e., at night and thus it is present on the edge of leaves in the early morning.

Transpiration is the loss of water through stomata in vapour form. Transpiration is regulated through guard cells. Guttation is the loss of water in liquid form through hydathodes. Hydathodes are free ends of vascular supply of leaves. Hydathodes are always open and not regulated by any cells.

Guttation is the loss of water in  the form of liquid through hydathodes or water stomata. It occurs due to positive root pressure and serves to remove excess water from the plant. As xylem sap is having dissolved minerals, water droplets that ooze out from them contain solution of water and minerals. 

Transpiration is defined as loss of water as gas or vapour from leaves through the stomatal pore. If there is less transpiration due to high atmospheric humidity and the soil is well watered; there will be an increase in root pressure. The increased root pressure leads to oozing out of the solution of minerals from hydathodes (called as guttation) and other openings (called as bleeding). Thus, the correct answer is option D.

Toddy refers to fermented palm wine. It is prepared by fermentation of sap obtained from palm trees. The process of obtaining sap from trees is through bleeding of plant. The sap is extracted and collected by a tapper. Typically the sap is collected from the cut flower of the palm tree. A container is fastened to the flower stump to collect the sap. The white liquid, that initially collects tends to be very sweet and non-alcoholic before it is fermented.

Bleeding takes place through injured organs of the plant. It usually describes fluid oozing from injured plant parts. Transpiration describes the loss of water in vapour form and helps in cooling of leaf surface as well as the movement of mineral ions in transpiration stream. Transpiration is primarily responsible for uptake of water circulating in plant's xylem vessels and tracheids.

Oozing out of water drops from injured edges or tips in plants is called bleeding. Bleeding usually develops because of the pressure of sap inside of the tissues which conducts water and sugars around the plant. If any positive pressure exist in the xylem due to any cut or opening results in the exudation or bleeding of the solution from the trachery elements.

When water oozes out from the pores of the plants known as Hydathodes then it is known as Guttation.

Hydrophytes are water loving plants. The hydrophytes with floating leaves have large leaves, stomata and waxy coating on the upper surface. The waxy coating prevent wetting and clogging of stomata.