Question

Define:
(a) Photon (b) Quantum (c) $C_3$ plants (d) $C_4$ plants (e) Light Reaction (f) photorespiration (g) Limiting Factor.

Answer 1

For (a) It is related to light energy and important for photosynthesis.
(b) It is related to physical entities and involves interaction.
(c) It is related to the process of carbon fixation.
(d) Also known as the Hatch-Slack pathway and is followed by some plants.
(e) Absorbing of light and use of energy.
(f) Involves loss of carbon in $CO_2$ plants.
(g) Factors that influence plant development.

Complete answer:
(a) Photon- It is a particle that constitutes the light. Photons are very important in the process of photosynthesis. Plants have the ability to capture these photons by the help of chloroplast. After the sufficient light energy that plants get, they create chemical molecules which are responsible for making food.

(b) Quantum- The minimum amount of physical property that is required in any interaction is termed as quantum. Plants can use quantum mechanics for the transfer of energy from chromophores to where the photosynthesis takes place. Energy particles behave like waves.

(c) $C_3$ plants- They are the normal plants that have not adapted to photosynthesis for reduction of photorespiration (which will be explained below). 85% plant species are the $C_3$ plants.

(d) $C_4$ plants- Here, the light dependent reactions and the Calvin cycle are separated. Light dependent reactions will occur in mesophyll cells and Calvin cycle occurs in the cells around leaf veins which are the bundle-sheath cells.

(e) Light Reaction- It shows that light is very important for the photosynthesis process. These reactions use light energy to make ATP and NADPH.

(f) Photorespiration- Here loss of fixed carbon as $CO_2$ takes place in presence of light. It is also the other name of the $C_2$ cycle. It is initiated in chloroplasts.

(g) Limiting Factor- Factors which affect the photosynthesis rate can be the limiting factors no matter how much the levels of other factors are.

Note:(a) Photons can also determine a light’s PPF which is the photosynthetic photon reflux. PPF quantity can be measured to know how responsive plants are to different light types.
(b) Quantum effects could be seen in living entities by the scientists. Molecules responsible for photosynthesis exhibit quantum behavior.
(c) Examples of $C_3$ plants are rice, soybeans, wheat and trees.
(d) Examples of $C_4$ plants include sugarcane, sorghum, maize and many others.
(e) $CO_2$, water, chlorophyll and light are the most essential things required in light reaction.
(f) Photorespiration is not responsible for generating ATP. Oxygen usage is not there and no $CO_2$ is produced.
(g) Important limiting factors are temperature, light and carbon dioxide.