Biology Test 307

Photosynthesis is not directly regulated by plant growth regulators. While plant hormones influence growth, development, and responses to environmental stimuli, photosynthesis is primarily affected by light, carbon dioxide, and water availability. Plant growth regulators, however, can indirectly affect photosynthesis by influencing leaf development and opening or closing of stomata.

The main precursor for the synthesis of gibberellins is mevalonic acid, which is derived from acetyl Co-A. Gibberellins are a large family of chemicals that play key roles in promoting growth and overcoming dormancy in plants. An interesting fact is that there are more than 100 different gibberellins identified in plants and fungi.

glycocalyx is carbohydrate

Arithmetic growth in plants is characterized by a linear increase in size. This type of growth occurs when one daughter cell continues to divide after mitosis while the other differentiates and matures, leading to a steady, linear increase in the organ's size over time. This contrasts with geometric growth, which is exponential.

The net gain of ATP from one molecule of glucose during glycolysis is 2 ATP. Although 4 ATP molecules are produced, 2 ATP molecules are used in the early stages of glycolysis, resulting in a net gain of 2 ATP. This process provides cells with a quick supply of energy, especially important under anaerobic conditions or when energy demands exceed the capacity of aerobic respiration.

The Krebs cycle, occurring in the mitochondrial matrix, is crucial for cellular respiration because it generates electron carriers (NADH and FADH2) and CO2 as by-products. These electron carriers are essential for the Electron Transport Chain, where the bulk of ATP is produced. The Krebs cycle does not produce glucose or directly convert ADP to ATP, nor does it capture light energy, which is a function of photosynthesis, not respiration.