Test: Chloroplast & Chlorophyll - NEET MCQ

Photosynthetically active radiation. Photosynthetically active radiation, often abbreviated PAR, designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis.

• Chlorophyll is not an accessory pigment as it the chief pigment of the chloroplast.
• Chlorophyll b, xanthophyll, and carotenoids are accessory pigments.
• Bacteriochlorophyll and phycobilin are other pigments present in leaves.

• In chloroplast, chlorophyll-a is more than chlorophyll b.
• They are not present in equal proportion. Since chlorophyll-a is the main chief pigment in photosynthesis, it is more in number.
• Chlorophyll b is less in number since it is only an accessory pigment.

• Interconnected sacs: This is not the correct arrangement of thylakoids in chloroplasts. While thylakoids are interconnected, they are not in the form of sacs.


• Interconnected discs: Thylakoids are not arranged as interconnected discs. This option is also incorrect.


• Stacked discs: The correct arrangement of thylakoids in chloroplasts is as stacked discs. Thylakoids are organized into stacks called grana, which are made up of interconnected discs containing the photosynthetic pigments.


• None of the above: This option is incorrect as the correct answer is option C, stacked discs.

Therefore, the correct arrangement of thylakoids in chloroplasts is as stacked discs, forming grana, where the light-dependent reactions of photosynthesis take place.

• Parallel Layering of Membranes: The parallel layering of membranes in chloroplasts allows for an increased surface area for light absorption.


• Suited for Maximum Light Absorption: The arrangement of membranes in chloroplasts is specifically suited for capturing as much light energy as possible for photosynthesis.


• Optimal Exposure to Light: The parallel layering ensures that chloroplasts are exposed to light from various angles, maximizing the absorption of sunlight.


• Enhanced Efficiency: This structural adaptation enhances the efficiency of photosynthesis, allowing plants to convert light energy into chemical energy more effectively.

There is clear division of labour within the chloroplast. the membrane system is responsible for the light reaction ( trapping light energy and synthesis of ATP and NADPH) while dark reaction i.e., enzymatic reactions for the reduction of carbon dioxide into sugar using ATP and NADPH take place in the stroma.

Chlorophyll is a specialised light absorbing pigment which is found in the inner wall of granum. Each granum is a flat, sac-like structure in which light reaction of photosynthesis takes place.

Chloroplasts are photosynthesizing organelles, at which photosynthetic pigment chlorophyll captures, transforms and stores the energy from sunlight in the energy storage molecules NADPH and ATP while liberating oxygen from water in algal and plant cells. In a process referred to as the Calvin cycle, they use the ATP and NADPH to produce organic compounds from carbon dioxide.

Now, let us find the solution from the options-
- In the thylakoid membranes of the organelle, the chloroplast is a plastid containing chlorophyll (green pigment).
- Thylakoid can be described within the chloroplasts of a plant cell as a membrane-bound compartment.
-It is the area of photosynthesis light-dependent reactions.
- Thylakoid comprises a membrane of thylakoid containing thylakoid lumen.
-A load of thylakoid or lamella discs is known as grana.

Thus, the correct answer is option (A) Grana.

Note: At least 3 membrane systems are available for all chloroplasts: the outer chloroplast membrane, the thylakoid system, and the inner chloroplast membrane. There may be extra membranes encircling these three chloroplasts which are the product of secondary endosymbiosis.

Chloroplasts are the green plastids which take part in photosynthesis and temporary or  permanent storage of starch. These are discoid (disc-shaped) in higher plants with diameter of 4-6 μm and thickness of 2-4.μm.

• Chloroplast: Thylakoids are membrane-bound compartments inside the chloroplast where the light-dependent reactions of photosynthesis take place.


• Endoplasmic reticulum: Thylakoids are not found inside the endoplasmic reticulum. The endoplasmic reticulum is involved in protein synthesis and lipid metabolism.


• Mitochondria: Thylakoids are not found inside the mitochondria. Mitochondria are responsible for cellular respiration.


• Golgi apparatus: Thylakoids are not found inside the Golgi apparatus. The Golgi apparatus is involved in packaging and processing proteins.

Therefore, the correct answer is A: Chloroplast. Thylakoids occur inside the chloroplast, specifically in the grana, where they play a crucial role in the process of photosynthesis.