Biology Test 317

Chlorophyll a, shows higher rate of photosynthesis. Hence, it is conclude that chlorophyll a is the chief pigment associated with photosynthesis.

The key features of plant photosynthesis were known, namely, that plants could use light energy to make carbohydrates C₆H₁₂O₆ from CO₂ and water, Where C₆H₁₂O₆ represents glucose.

Each photosystem has all the pigments (except one molecule of chlorophyll a) forming a light harvesting system also called antennae. These pigments help to make photosynthesis more efficient by absorbing different wavelengths of light.

Phytochrome absorbs red of wavelength 660nm and far red of wavelength 730nm.

The C₄ plants respond to higher temperatures and show higher rate of photosynthesis while C₃ plants have a much lower temperature optimum.

The central element of chlorophyll contain Magnesium element.

This option is correct. Cyt b₆-f complexes are evenly distributed in the stroma and granal thylakoids.

Photolysis of water is mainly carried out to compensate the electrons that are transferred to photosystem I by photosystem II during the non-cyclic photophosphorylation that reduce NADP⁺ into NADPH.

Most of the plants that are adapted to dry tropical regions have the C₄ pathway. e.g. Sugarcane, Maize, Sorghum,etc. These plants are known as C₄ plants. For the formation of sugars, C₄ plants undergo C₄ cycle as well as C₃ cycle or Calvin cycle. In these plants double fixation of carbon dioxide occurs.

ATP consumed in C₄ plants:

C₄ cycle - 2 ATP per CO₂ fixed

C₃ cycle - 3 ATP per CO₂ fixed 

Total - 5 ATP per CO₂ fixed

Thus, to form one molecule of glucose or to fix 6 CO₂, 6 X 5 = 30 ATP are consumed.

In chloroplast there is the membranous system consisting of grana, the stroma lamellae, and the fluid stroma. There is a clear division of labour within the chloroplast. The granum is responsible for trapping the light energy.