Biology Test 30

Nickel is generally not considered as an essential element for the plant growth. Moreover nickel above the tolerable range can also be dangerous.

Day neutral plants do not need a specific photoperiod to produce flowers. They are also called intermediates or photoneutrals. Their photoperiod varies from a few hours to 24 hours of uninterrupted light, eg, tomato, cucumber, sunflower, maize and cotton etc.

emerson and lewis exposed chlorella to different wavelengths of monochromatic light and measured the quantum yield. Rate of photosynthesis increases with increasing of light but it abruptly declined beyond red zone. The reduction is due to inhibition of PSII in far red light. This is known s red drop

Gibberellin promotes intermodal elongation in a wide range of species. This intermodal elongation phenomenon is known as blotting. It is a plant growth hormone, which was first time obtained from a fungus Gibberella fujikuroi (Fusarium moniliformi).

Ethylene promotes ripening of food & Leaf abscission. It also inhibits stem elongation.

Gibberlins promotes seed germination, Stem growth and fruit development, inhibit winter dormancy.

The effect of light duration and dark duration on growth and development of plants is known as photoperiodism, it affects the overall plant growth of root and shoot apex, flowers and leaves.

Cytochrome oxidase is one of a superfamily of proteins which act as the terminal enzymes of respiratory chains. The two main classes are cytochrome c oxidases and quinol oxidases. It acts as an endoenzyme.

• There are two catalytic subunits, I and II
• Subunit I contains two heme centres. The first of these (heme an in cytochrome oxidase) acts as an electron input device to the second. The second heme (heme a₃ in cytochrome oxidase) is part of a binuclear centre, with a Cu (Cu_Bin cytochrome oxidase) as the other metal. The binuclear centre is the site of oxygen reduction.
• Subunit II processes the electron donation. In cytochrome c oxidases, the subunit contains a Cu centre (Cu_A) with 2 Cu atoms, which is thought to be the immediate electron acceptor from cytochrome c. A possible electron transfer pathway from this centre to heme a has been identified in the structure. In quinol oxidases, this subunit processes the quinol substrate.

Fermentation refers to the metabolic process by which organic molecules are converted into acids, gases, or alcohol in the absence of oxygen or any electron transport chain. Fermentation pathways regenerate the coenzyme nicotinamide adenine dinucleotide (NAD⁺), which is used in glycolysis to release energy in the form of adenosine triphosphate (ATP). 
 The two fermentations most commonly used by humans to produce commercial foods are:

• ethanol fermentation 
• lactic acid fermentation.

In the overall process, one molecule of glucose is converted into two molecules of carbon dioxide and two molecules of ethanol.

In Kreb cycle guanosine triphosphate (GTP) is formed in substrate level phosphorylation by the direct transfer and donation of a phosphoryl group to guanosine diphosphate (GDP) from a phosphorylated reactive intermediate.

simple diffusion or diffusion is a process in which molecules moves from higher concentration to lower concentration.. In simple diffusion, there is no role of carrier proteins and as the movement of ions occurs along concentration gradient, so there is no expenditure of energy.. Movement of ions only takes place until an equilibrium is not established.