Plants growing in tropical regions are exposed to an optimum temperature of 30°C to 45°C.
Anatomically these plants have Kranz anatomy and dimorphic chloroplasts. The vascular bundles are surrounded by a layer at bundle sheath. Bundle sheath is surrounded by a ring of Mesophyll cells.
Dimorphic Chloroplast :Bundle sheath chloroplast are larger and thylakoids are not arranged in granum.
Mesophyll Chloroplast are small and thylakoids are arranged in granum.
Plants with this kind of anatomy have the C₄ cycle or Hatch and slack pathway which takes place in two phases.
First phase in stroma of mesophyll cells and phase II in Bundle sheath cells.
Advantage of this cycle is that fixation of carbon di oxide by such plants can occur ever when the atmospheric carbon di oxide concentration is less than 10ppm.
But the cycle consumes 30 ATPs to produce one glucose molecule.

C₄ plants show Kranz anatomy. In C₄ plants vascular bundles are surrounded by a layer of bundle sheath. Bundle sheath is surrounded by a ring of Mesophyll cells. Dimorphic chloroplast is a characteristic feature is C₄ plants.
Bundle Sheath chloroplast : Larger chloroplast, thylakoids not arranged in granum
Mesophyll chloroplast : Smaller chloroplast, thylakoids arranged in granum.

According to Blackman, "at any given point of time the lowest factor among essentials will limit the rate of photosynthesis". For example, when even sufficient light intensity is available, photosynthesis may be low due to low CO₂ in the atmosphere. Here, CO₂ acts as a limiting factor.

When the rate of photosynthesis equals the rate of respiration, there is no exchange of oxygen and carbon dioxide and this is called as carbon dioxide compensation point.

The first product is a 4-carbon and so it is named as C₄ cycle. Oxalo acetic acid is a dicarboxylic acid and hence this cycle is also known as dicarboxylic acid pathway.

DCMI stands for dichloro dimethyl urea. It can inhibit electron flow during light reaction of photosynthesis. Non cyclic photophosphorylation can be inhibited by DCMI.

During the Noncyclic photophosphorylation in light reaction of photosynthesis, the electron flow looks I like the appearance of letter 'Z' and is known as 'Z' scheme.

A curve obtained by plotting the amount of absorption of different wavelengths of light by a pigment is called its absorption spectrum.

Bioluminescence is the production and emission of light by a living organism. Bioluminescence is rare in true plants.

Quantasomes are the morphological expression of physiological photosynthetic units, located on the inner membrane of thylakoid lamellae. One quantasome contains about 230 chlorophyll molecules. It constitutes a photosynthetic unit.

In some bacteria, oxygen is not evolved during photosynthesis and is called as non-oxygenic and anaerobic photosynthesis. Ex: Green sulphur, Purple sulphur and green filamentous bacteria.

(i) No. there is no scientific proof for this statement. During day time photosynthesis takes place oxygen is evolved.
(ii) This reaction requires light hence the above statement is incorrect.

(i) Group A shows maximum photosynthesis. chlorophyll pigments of the spectrum is (400 - 450 nm), hence the photosynthesis is high.
(ii) Group B will show negligible amount of photosynthesis, because chlorophyll does not absorb any light in this region (500 - 550nm). It reflects green.

The plants undergoes Photorespiration.
(i) It is the excess respiration taking place in photosynthetic cells due to absence of CO₂ and increase of O₂.
(ii) This condition changes the carboxylase role of RUBISCO into oxygenase.