Photosynthesis is the process by which green plants convert light energy into chemical energy in the form of glucose. It occurs in the chloroplasts of plant cells and involves two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle).

- Light-dependent Reactions: These reactions occur in the thylakoid membranes of the chloroplasts. They require light energy and involve the splitting of water molecules into oxygen, electrons, and protons. The energy from light is used to produce ATP and NADPH, which are then used in the next stage.

- Light-independent Reactions (Calvin Cycle): These reactions occur in the stroma of the chloroplasts. They do not directly require light but rely on the products of the light-dependent reactions. Carbon dioxide is converted into glucose through a series of enzyme-controlled reactions. ATP and NADPH generated in the light-dependent reactions provide the necessary energy and reducing power.



Respiration in plants is the process by which they break down glucose to release energy for various cellular activities. It occurs in the mitochondria of plant cells and involves three main stages: glycolysis, Krebs cycle, and oxidative phosphorylation.

- Glycolysis: This process occurs in the cytoplasm and involves the breakdown of glucose into two molecules of pyruvate. It produces a small amount of ATP and NADH.

- Krebs Cycle: Also known as the citric acid cycle, this process occurs in the mitochondria. Pyruvate is further broken down, releasing carbon dioxide and producing ATP, NADH, and FADH2.

- Oxidative Phosphorylation: This process occurs in the inner mitochondrial membrane. NADH and FADH2 produced in the previous stages transfer electrons to the electron transport chain, generating a large amount of ATP through the process of chemiosmosis.



Plant growth and development are regulated by various internal and external factors. The main processes involved are cell division, cell elongation, and cell differentiation.

- Cell Division: Plant cells divide through the process of mitosis, which allows for growth and the formation of new tissues.

- Cell Elongation: After cell division, cells elongate by absorbing water and expanding. This is facilitated by the presence of auxins, a class of plant hormones.

- Cell Differentiation: Differentiation refers to the specialization of cells into specific types, such as root cells, leaf cells, or stem cells. This process is regulated by various plant hormones, including auxins, cytokinins, gibberellins, and abscisic acid.



Plants respire through small openings called stomata present on their leaves and stems. This process involves the exchange of gases, including oxygen and carbon dioxide, with the surrounding environment.

- Breathing: Plants take in oxygen for cellular respiration through the stomata. Oxygen is required for the breakdown of glucose to release energy.

- Exchange of Gases: The stomata also allow for the exchange of carbon dioxide, which is a byproduct of respiration, with the atmosphere. Carbon dioxide enters the leaves through the stomata and