Plant Physiology and Botany Test

Photolysis of water (the splitting of water molecules) occurs in the lumen of the thylakoid and is associated with Photosystem II (PS II) to provide electrons for the electron transport chain.

Hydroponics is a method of growing plants without soil, using mineral nutrient solutions in an aqueous solvent.

The rate of translocation of organic solutes (photosynthates) in the phloem sieve tubes is generally accepted to be in the range of 50 to 100 cm/hour.

Yeast is a facultative anaerobe, meaning it can perform cellular respiration in the presence of oxygen and switch to fermentation (anaerobic respiration) in the absence of oxygen.

Soil salinity is typically measured by determining the electrical conductivity of a soil extract, as dissolved salts increase the conductivity of the solution.

Quantosomes are considered the structural units of the thylakoid membrane, and it is widely cited in older botanical literature that a quantosome contains approximately 250 chlorophyll molecules.

Deplasmolysis is the reverse of plasmolysis. When a plasmolyzed cell is placed in a hypotonic solution, water enters the cell by endosmosis, causing the protoplast to swell and return to its original state.

The plasma membrane is selectively permeable, regulating the passage of water, ions, and organic molecules into and out of the cell to maintain homeostasis.

The starch-sugar interconversion hypothesis for stomatal opening was proposed by Sayre (1923) and further developed by Steward (1964).

When a plant is burned, organic matter is oxidized and released as gases (CO2, H2O), leaving behind the inorganic mineral salts as ash.

Dieback disease in citrus trees is a physiological disorder primarily caused by a deficiency of copper in the soil, which affects the tree's growth and health.

Stomatal transpiration, which occurs through the stomata located in the dermal tissue (epidermis) of leaves, accounts for the vast majority of water loss in plants.

Chlorosis is the yellowing of leaves due to a lack of chlorophyll. Magnesium is a central atom in the chlorophyll molecule, and iron is required for its synthesis, so their deficiency leads to chlorosis.

Plasmolysis occurs when a cell is placed in a hypertonic solution. Water leaves the cell via osmosis (specifically ex-osmosis), causing the protoplast to shrink away from the cell wall.

Potassium is the most abundant intracellular cation in living cells, playing a crucial role in maintaining osmotic balance and membrane potential. Phosphorus and sulphur are primarily structural or metabolic components, while iron is a trace element.

A manometer is a device used to measure pressure, including the root pressure exerted by plants. A potometer measures transpiration rates, while a barometer measures atmospheric pressure.

The transpiration-cohesion-tension theory is the most widely accepted explanation for how water moves upward through the xylem against gravity. It relies on the cohesive properties of water and the pull generated by transpiration.

A semipermeable membrane is selectively permeable, allowing the passage of solvent molecules (like water) while restricting the passage of larger solute molecules. This is the fundamental principle of osmosis.

Photorespiration occurs when the enzyme RuBisCO binds with oxygen instead of carbon dioxide. This process is favored under conditions of high oxygen concentration and low carbon dioxide concentration, often occurring in hot, dry environments.

Diffusion Pressure Deficit (DPD), also known as suction pressure, represents the actual force that drives water into a cell. It is defined as the difference between the osmotic pressure and the turgor pressure of the cell.

Phosphorus is a vital macronutrient for plants, essential for energy transfer (ATP) and root development. It is often added to fertilizers to promote strong, healthy root systems.

Melvin Calvin and his colleagues used the unicellular green alga Chlorella in their pioneering experiments to map the carbon fixation pathway in photosynthesis.

Water absorption by roots is an active process that depends on metabolic activity. Temperatures between 20 and 35 degrees Celsius are generally optimal for root metabolism and water uptake.

In water-logged soil, oxygen is displaced by water. This creates an anaerobic environment that prevents root respiration, making it difficult for the plant to absorb water, a condition known as physiological drought.