FREE NEET Biology Practice MCQ Test: Photosynthesis In Higher Plants Exercise 3 Questions Answers With Detailed Explanations [PDF]

Answer: (c)

In Photosystem I or Photoact I electrons released by P-700 are accepted by a substance of iron-sulphur-protein complex denoted as A(FeS). A(FeS) is thus reduced and it passes these high electrons to oxidised ferredoxin and it gets reduced. From reduced Fd these electrons are passed to FAD which now reduced to $FADH_{2}$ and then electrons and hydrogen are accepted by NADP which makes $NADPH_{2}$. Here photosystem I ends.

Answer: (a)

Answer: (a)

$C_4$ pathway was first reported in members of Family Gramineae (grasses) like sugarcane, maize, sorghum, etc.

Answer: (d)

Rate of net photosynthesis in $C_3$ plants is 15-35 mg $CO_2$ /$dm^2$/hr while in $C_4$ plants it 40-80 mg $CO_2$ /$dm^2$/hr. This variation in rate is due to photorespiration. Photorespiration is an inhibitory process which decreases the rate of photosynthesis. In excess of oxygen RuBP carboxylase converts to RuBP oxygenase. As a result glycolate synthesis is enhanced and leads to begin photorespiration. Photorespiration is negligible or absent in $C_4$ plants and present only in $C_3$ plants. So $C_4$ plants are photosynthetically more efficient.

Answer: (d)

Answer: (a)

Answer: (d)

The dark reactions or Blackman's reactions or biosynthetic phase involves three steps: (i) Fixation of $CO_2$ , (ii) Reduction of $CO_2$ and (iii) Synthesis of other compound from glucose. It is independent of light. Pigment System I is relatively very weakly fluorescent while pigment system II is strongly fluorescent. Light energy absorbed by pigment in the two systems is ultimately trapped by the $P_700$ and $P_680$ . Light reaction is associated with the grana of the chloroplasts. It takes place in the presence of light only.

Answer: (c)

Rate of yield is dependent of light as photosynthesis is dependent on light. Maximum rate of photosynthesis occur when light is brightest (high light intensity). But during monsoon, the light is dim (low light intensity) and so this reduces rate of photosynthesis and hence yield.

Answer: (b)

Answer: (d)

Answer: (c)

Water molecule breaks up into hydrogen and oxygen in the illuminated chloroplasts. This is called photolysis of water. If a photosynthesising plant is releasing $^{18}O$ more than the normal, the plant must have been supplied with $H_2O$ with $^{18}O$.

Answer: (c)

As the intensity of light increases, the rate of photosynthesis also increases. But at higher light intensity, the rate of photosynthesis decreases, because of the following reasons–

(i) other factors required for photosynthesis become limiting.

(ii) destruction of chlorophyll occurs, so there will be no carbohydrate (sugar) formation.

Answer: (b)

Answer: (c)

Photosynthetically Active Radiation (PAR) ranges from400-700 nm. This is the visible range of light energy. The range of other wavelengths are100-300 nm:Ultraviolet (UV) range390-430 nm:Infrared (NIR) range760-100,00 nm:Mid Infrared (MIR) range

Answer: (a)

Answer: (c)

In some photoautotrophic bacteria bacteriochlorophyll and bacteriophaeophytin or bacterioviridin pigments containing membraneous extensions called chromatophores are present. These are sites of bacterial photosynthesis .

Answer: (d)

Accessory pigments are light-absorbing compounds that traps light energy and channels it to chlorophyll a which initiates the reactions of photosynthesis. Accessory pigment includes the carotenoids, phycobiliproteins, and chlorophylls b, c, and d. Indeed, they not on enable a wider range of wavelength of incoming light to be utilized for photosynthesis but also protect chlorophyll a from the photo-oxidation.

Answer: (a)

Answer: (d)

Answer: (c)

Water is split at photosystem–II to donate electrons to the reaction centre. The resulting protons are moved across the membrane to establish the proton motive force and oxygen is given off as a by-product.