Question

Quantasomes occur on the surface of
(a) Cristae
(b) Plasmalemma
(c) Nuclear envelope
(d) Thylakoids

Answer 1

 
Hint: Quantasomes are considered as a part of the photosynthetic units. They contain pigments and redox carriers. They are present in the membranes of certain stacks present inside the photosynthetic plastids in plants and bacteria.

Complete Step by Step Answer:
Quantasomes are composed of lipids and proteins and include various redox carriers and photosynthetic pigments. They are the particles that are found in the thylakoid membranes of the chloroplasts in which photosynthesis takes place. They are present, embedded in a paracrystalline array over the surface of thylakoid discs present inside the chloroplasts.
- Quantasomes were first identified in 1962 by Roderic B. Park
- These quantasomes are considered to be the sites for the action of photosystems.
- These photosystems are the protein complexes that are involved in photosynthesis and they carry out the primary photochemistry of photosynthesis that is the absorption of light and transfer of energy. Photosystems are found inside the thylakoid membranes, specifically the quantasomes of plants, algae, and cyanobacteria.
These photosystems are of two types PS I and PS II.
The PSI photosystem has a reaction center ${P}_{700}$ that best absorbs light of wavelength 700nm. The PSII photosystem has a reaction center ${P}_{680}$ which is highly oxidizing and takes part in the splitting of water. Thus both the photosystems are necessary for photosynthesis.

So, the correct answer is ‘Thylakoids’.

Note: 
- Quantasomes are considered to be photosynthetic units as they are seen on the surface of thylakoids embedded in their membranes.
- Quantasomes occur in 2 different sizes:
- The smaller quantasomes are thought to be representing the sites of photosystem I action whereas the larger quantasomes represent the site of photosystem II action.