Tag: plastids

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.

Chlorophyll absorbs sunlight of particular wavelength that causes spitting of water at water splitting complex of photosystem II and oxygen gas is released. PSI absorbs light below 680nm while PS II is activated by light below 700 nm; so plants exhibit maximum amount of oxygen released when illuminated with simultaneous exposure to red and far red light. Fixation of $CO _2$ occurs during the dark reaction. Thus, the correct answer is B.

Total amount of dry weight of photosynthate produced by all type of plants per annum is 170000 million tonnes. There are several factors, which limit the formation of dry weight such as reduced nitrogen fixation which will result in reduction of dry weight.

Blue green algae are prokaryotic orgnanisms and lack membrane bound organelles. Mitochondria and cholroplast are double membrane bound organelles of eukaryotes that serve as site of aerobic respiration and photosynthesis respectively. Chromatophores are the pigment containing membranous structures that serve as site for photosynthesis in BGA. Correct answer is A.

• Thylakoid (internal photosynthetic membranes) is a membrane-bound compartment present within the cellular organelle called chloroplast, they are also present in cyanobacteria.
  
• It is a site for the light-dependent reactions of photosynthesis. 
• It is made up of a thylakoid membrane which surrounds the thylakoid lumen.
• The term thylakoid was coined by Menke in the year 1962.
  
• So, the correct answer is 'Menke'.

Intact chloroplast from green leaves can be isolated by the acetone isolation method. The membranes of the chloroplast are proteinaceous in nature so it can be easily isolated by acetone. The samples obtained are loaded to the chromatography apparatus, which shows bands on the chromatogram.

So, the correct option is B.