Test: Plant Physiology (July 24) - NEET MCQ

Scarification is the breaking of the seed coat  barriers which can be done by mechanical or chemical methods. 

 IAA promotes apical dominance. ABA induces dormancy in buds.

Photosystem I is the second photosystem in the photosynthetic light reactions of algae, plants and some bacteria. Photosystem I is so named because it was discovered before photosystem II. It produces NADPH₂.

Respiratory quotient (R.Q.) is defined as the ratio of the molecules of carbon dioxide given out to the number of oxygen molecules taken in during respiration. Its value for fatty acids is always less than unity.

In Anaerobic respiration, oxygen is not used in the breakdown of respiratory substrate.

Light reaction is the first step of  photosynthesis. Attachment of  CO₂ to 5 carbon sugar occurs in the next step dark reaction

RUBISCO  is the enzyme involved in Calvin cycle. Nitrogenase catalyses nitro- genation. Invertase catalyses breaking of sucrose to glucose and fructose.

Firstly, amylose and glycogen are converted to glucose. Deamination of ketogenic amino acids occur and these enter respiratory catabolism as intermediates.

Photosynthesis takes place only in the visible part (400 - 700 nm wavelength) of electromagnetic radiations. Hence this component comprises the photosynthetically active radiation.

In northern India, during these  months there is observed maximum variation in light intensity and duration and temperature. Hence only plants that are photo-and thermoinsensitive can flower during these months.

 Cytokinins are used in tissue culture to induce shooting of the cultural callus.

ATP is injected in cyanide poisoning because it is necessary for cellular functions. ATP makes energy available at a spot away from the area of release of energy so it helps in maintaining cellular functions.

Ethylene acts physiologically as a hormone in plants. It stimulates the ripening of fruit, the opening of flowers, and the abscission (or shedding) of leaves. Its biosynthesis starts from methionine with 1-aminocyclopropane-1-carboxylic acid (ACC) as a key intermediate.

2 ATP are required during conversion of PGA to 1, 3-diphosphoglyceric acid and 1 ATP during conversion of glyceraldehyde phosphate to ribulose biphosphate. 2NADH₂ molecules are utilised for converting 1, 3-diphosphoglyceric acid to glyceraldehyde phosphate.

Glycolysis is the first step of respiration which occurs without requirement of O₂ and is common to both aerobic and anaerobic modes of respiration.