Tag: photosynthetic pigments

Thylakoid is a sheet-like membrane-bound structure which is the site of the light-dependent photosynthesis reactions within the chloroplasts and cyanobacteria. Photosystems are then functional and structural units of protein complexes involved in photosynthesis.

The electron transport chain is a series of the proteins and organic molecules which are found in the inner membrane of the mitochondria. Photolysis is the chemical process by which molecules are broken down into smaller units through the absorption of light.

The synthesis of ATP in chloroplasts, promoted by light, is termed as photophosphorylation

So the correct option is A.

Phytochrome is a light sensitive pigment in plants and some bacteria and fungi. It exists in two interconvertible forms- Pr and Pfr. Pfr absorbs far red light of 730 nm wavelength. When it absorbs far red light, it converts to its original form, Pr. Thus Pfr is the active form of phytochrome which inhibits flowering.

Chlorophyll pigments trap sunlight during the process of photosynthesis but get destroyed on exposure to light of higher intensity. An exposure to high light intensity for even a small duration can be harmful. The destruction of chlorophyll when exposed to light of high intensity is called as solarization. It occurs due to irreversible chemical changes in the structure of chlorophyll molecule.

Plants are able to detect and respond to light, gravity, changes in temperature and chemicals. Plants respond to the changing seasons to initiate their development and flowering. The photoperiodic stimulus is found to be responsible for flowering, light quality, vernalization, autonomous and GA pathways are also responsible for regulating the flowering time in plants. While vernalization and photoperiodic pathways are environmental dependents, the autonomous pathway promotes flowering in all conditions. Hence for a tree that flowers thrice a year, the plant has to be both photo and thermo-insensitive.

Photosynthetic units are referred as quantasomes. Quantasomes are particles found in the thylakoid membrane of chloroplasts in which photosynthesis takes place.

Photosynthesis is a redox reaction in which carbon dioxide is reduced to sugars in dark reaction and water is oxidised to release oxygen in light reaction of photosynthesis. $C^{14}$ label was used to trace the path of carbon in the dark reaction in $C _3$ plants by Calvin, Benson and Basham. The $O^{18}$ label was used by Rumen and Kamen to experimentally prove that the source of oxygen released during light reaction of photosynthesis is water.

The main photoreceptor for photoperiodism and many other light initiated plant responses (such as germination and seedling establishment) is phytochrome. It is a family of about five blue-green pigment proteins, each of which is coded for by a different gene in higher plants, like angiosperms. 

The eukaryotic cell also possesses several membrane-bound organelles. The cell is composed of the nucleus, Golgi complex, lysosome, chloroplast, mitochondria, etc. Chlorophyll is the coloured pigment inside the chloroplast which is involved in the process of photosynthesis.

Option 'E' is true.

The process of photosynthesis takes place in the chloroplasts, using chlorophyll, the green pigment involved in photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide gas to produce food for the plant. Chloroplasts capture light energy from the sun to produce the free energy stored in ATP and NADPH through a process called photosynthesis.