Photosynthesis in Higher Plants Test - 8

During this process, the electrons in water are removed and passed to the reaction center chlorophyll. The associated hydrogen ions are released from the water molecule, and after two water molecules are thus split, the oxygen atoms join to form molecular oxygen (O2), a waste product of photosynthesis.

Photosynthesis is the process by which organisms that contain the pigment chlorophyll convert light energy into chemical energy which can be stored in the molecular bonds of organic molecules (e.g., sugars). During the process of photosynthesis, light penetrates the cell and passes into the chloroplast. The light energy is intercepted by chlorophyll molecules on the granal stacks. Some of the light energy is converted to chemical energy. During this process, a phosphate is added to a molecule to cause the formation of ATP. The third phosphate chemical bond contains the new chemical energy. The ATP then provides energy to some of the other photosynthetic reactions that are causing the conversion of CO₂ into sugars.

Dark reaction in photosynthesis is called so because it does not directly depend on light energy.

Photosynthesis is the process of carbon fixation which mainly takes place in two steps, light reaction, and dark reaction. ATP and NADPH2​ are produced in the light reaction which is utilized for carbon fixation during the dark reaction. When the plant makes the glucose molecule, it gets the carbon and oxygen atoms it needs from carbon dioxide, which is taken by the air through the stomatal openings. Carbon dioxide doesn't have any hydrogen in it, though, so the plant must use another source for hydrogen. The source that it uses is water. 

So, the correct answer is option B.

Photosynthetic cells contain special pigments that absorb light energy, chlorophyll, the primary pigment used in photosynthesis, reflects green light and absorbs red and blue light most strongly.
The part of the solar spectrum used by plants has an estimated mean wavelength of 570 nm, therefore, the energy of light used during photosynthesis is approximately 28,600/ 570 per einstein.

The maximum photosynthesis takes place in blue and red regions of the visible light as indicated by the absorption spectra of chlorophyll a and chlorophyll b. Absorption spectrum of a particular pigment is the curve plotted on a graph paper representing the amount of light absorbed at each wavelength by that pigment. The absorption spectra of these pigments show that they absorb maximum at 480 nm (blue light) and 680 nm (red light) regions of spectrum.

Thus, the correct answer is option C.

The photosynthetic rate is influenced by many external (light, temperature, carbon dioxide, water, oxygen) and internal (chlorophyll content, protoplasmic condition, accumulation of end products) factors. The concentration of carbon dioxide in the atmosphere is 0.03 percent (300 parts per million). Plants can thrive well in this condition.

In the year 1937 and 1939, Robert hill studied the light dependent reaction and revealed that oxygen evolved during photosynthesis came from water. In his experiment, he used Dichlorophenolindophenol (DCPIP) as a redox dye to measure the rate of photosynthesis. The dye is blue in oxidized state with a maximal absorption at 600 nm whereas in reduced, DCPIP is colourless.

Enzyme RUBISCO has an affinity for both CO₂ and O₂ and its name changes depending on who it is binding to. When it binds to oxygen, it is called ribulose bisphosphate oxygenase. Though the affinity of RUBISCO to oxygen is said to be more than that for CO₂, it depends upon the concentration of O₂ and CO₂ and temperature conditions which ultimately decide what RUBISCO binds to.

Emerson effect was observed by Robert Emerson in 1957. Emerson effect shows that photosynthesis proceeding very slowly when light of 700 nm wavelength is used can be increased by illuminating with light of shorter wavelength i.e. 650 nm. So, Emerson effect is related to increase in photosynthesis when lights of two different wavelengths are provided together. Emerson effect is also known as enhancement effect. It indicates the existence of two pigment systems, i.e. pigment system I and pigment system II.

So, the correct answer is option A.

The only color in the visible spectrum not used at all by green plants would be green because that is the light that is getting reflected off of the plant.

The process of photosynthesis is faster than respiration. This difference is crucial in making food available to all the living organisms in the food chain as all the organisms either directly or indirectly depend on photosynthesizing plants for food supply. Gross production of sugars or fixation of carbon dioxide minus respiratory losses in producers equals the net production. The rate of respiration in green plants has been reduced to suit the sedentary life style. The green plants have evolved for a sedentary life and most of the plant body is dead. In fact, most of the big woody trunk and brown areas of a plant body are dead and only the green leaves are living. This reduces the demand for food for respiration so that green plants are able to provide food to other more active organisms. The rate of respiration depends on the physiological demands of organisms. In active organisms energy demands are more and rate of respiration will be more. But in general usually, overall it is highly essential to have photosynthesis proceed at rates higher than respiration. 

So, the correct answer is option B.

Lime water absorbs carbon dioxide and hence there is no carbon dioxide for the leaf and hence photosynthesis does not take place and no starch is prepared. Hence on iodine test, the presence of starch is negative and thus proves that carbon dioxide is required for photosynthesis.

Richard Martin Willsttter, was a German organic chemist whose study of the structure of plant pigments, chlorophyll included, won him the 1915 Nobel Prize for Chemistry. He studied the structure of alkaloids (colorless, complex, and bitter organic compounds), anthocyanins (red, blue, and violet plant pigments), and chlorophyll (the green, light-absorbing catalyst in plants). He also corrected mistakes in the scientific understanding of cocaine's atomic structure and synthesized that drug, and pioneered the technique of chromatography ("color-writing"), developed independently by Willsttter and his student Arthur Stoll (1887-1971) in the 1920s.

So, the correct answer is option A.