Although photosynthesis is often summarised by a single equation, in fact the process occurs in two distinct phases; the light phase and another phase called the carbon fixation phase or the light independent phase - VCE - SSCE Biology - Question 3 - 2005 - Paper 1

Output X, or oxygen, is produced during the light phase of photosynthesis when water (H₂O) is split to release oxygen as a by-product. This process is part of the photolysis of water where the two hydrogens are utilized to form NADPH.

Output Y is a carbohydrate, specifically glucose or sugars.

Aerobic respiration in plants and animals depends on the oxygen produced during photosynthesis. Oxygen is essential for the aerobic breakdown of glucose to produce ATP. Since photosynthesis provides both glucose and oxygen, it is crucial for sustaining aerobic respiration.

An advantage of aerobic respiration is that it yields a much greater amount of adenosine triphosphate (ATP) per molecule of carbohydrate compared to anaerobic respiration. Specifically, aerobic respiration generates about 36 to 38 ATP molecules, while anaerobic respiration yields only 2 ATP.

Conclusion 1: Apical dominance is observed when the apical meristem is intact.

This conclusion is drawn from Group 1, which showed growth of the apical meristem but no lateral buds, indicating that the intact meristem inhibits lateral bud growth.

Conclusion 2: Apical meristem removal increases lateral bud growth.

This conclusion comes from Group 2, where the apical meristem was removed, leading to growth of lateral buds, signifying the lack of inhibitory signals that would suppress these buds.

Conclusion 3: The presence of auxin promotes lateral bud growth.

Group 3 shows that even when the apical meristem is removed, applying auxin results in growth of lateral buds, demonstrating auxin's role in stimulating bud development.