Question

Light reaction of photosynthesis occurs in
A. Stroma
B. Thylakoids of granum
C. Matrix
D. Chloroplast membrane

Answer 1

Hint:
Photosynthesis is a process by which light energy is converted into chemical energy in plants containing chlorophyll and some prokaryotes and bacterias. Intake of carbon dioxide along with water present in the plants participate in this process and stores the chemical energy produced in the form of sugars or carbohydrates and form oxygen in the presence of light.

Complete answer:
Chloroplast cells are the cells which contain chlorophyll pigment and following are the structures of chloroplast where photosynthesis takes place.

Option A- Stroma
It is the colourless fluid present within the chloroplast cells containing chlorophyll pigment. It is present within the inner membrane of the chloroplast. The dark reaction takes place in stroma which is also known as the Calvin cycle or light-independent reactions.

Option B- Thylakoids of granum
A stack of thylakoid discs of about 10-20 in number form a granum (grana in plural). These thylakoids are interconnected by stromal lamellae to the adjacent thylakoid discs of granum. The light reaction takes place in the discs. During this process, ATP and NADPH are formed with the seven steps of the reaction starting from absorbing light and passing the electrons.

Option C- Matrix
The matrix of chloroplast cells is called stroma which is explained above.

Option D- Chloroplast membrane
A chloroplast is made up of double-membrane which is also known as chloroplast envelope. It consists of the outer membrane, inner membrane and intermembrane space. The membranes play a role of permeability.

Thus, the correct option is option B- Thylakoids of granum.

Note:
Photosynthesis largely contributes to the production and maintenance of oxygen supply on Earth. The process occurs in two steps- light reaction and the dark reaction of photosynthesis.Factors affecting photosynthesis are light intensity, the concentration of carbon dioxide, temperature, water and pollution. Chlorophyll is a green colour pigment present in plants plays an important part in the process by allowing the plants to absorb energy from the source of light i.e. sunlight.