FREE NEET Biology Practice MCQ Test: Photosynthesis In Higher Plants Exercise 4 Questions Answers With Detailed Explanations [PDF]

Answer: (b)

The $C_4$ pathway allows photosynthesis to occur at very low concentrations of carbon dioxide as PEP carboxylase has an extremely high affinity for carbon dioxide. This pathway also works well at high temperatures and light intensity, enabling efficient photosynthesis in tropical plants.

Answer: (d)

C4 plants show kranz anatomy, i.e., the mesophyll is undifferentiated and its cells occur in concentric layers around vascular bundle, which is surrounded by large sized bundle sheath cells, in a wreath like manner. In this type of plants, the initial fixation of $CO_2$ occur in mesophyll cell. The primary acceptor (phosphoenol pyruvate) combines with $CO_2$ to form oxaloacetic acid which later reduces to malic acid. Malic acid is then translocated to bundle sheath cell for further decarboxylation.

Answer: (a)

Paper chromatography is an analytical method that is used to separate coloured chemicals or substances, especially pigments. This can also be used in secondary or primary colours in ink experiments. Leaf pigments of any green plants can be separated by using paper chromatography. A chromatographic separation of the leaf pigments shows that the colour we see in leaves is due to a single pigment but due to four pigments: chlorophyll a (bright or blue green in the chromatogram), chlorophyll b (yellow green), xanthophylls (yellow) and carotenoids (yellow to yellow orange).

Answer: (b)

The Calvin cycle is also known as C₃cycle because CO₂ reduction is cyclic process and first stable product in this cycle is a 3-C compound (i.e., 3-phosphoglyceric acid or 3-PGA). In this cycle, CO₂ acceptor molecule is RuBP or RuDP (i.e., Ribulose 1, 5-biphosphate or Ribulose 1, 5-diphosphate). There occurs covalent bonding of CO₂ to RuBP and the enzyme catalyzing this reaction is RuBP-carboxylase/oxygenase (RuBisCO).

Answer: (c)

Equation for $C_{4}$ pathway

6 PEP + 6 RuBP + 6CO 2 + 3 0 ATP + 12 NADPH + 6PE P + 6 Ru BP + $C_{6}H_{12}O_{6} + 30 ADP + 30 H_{3}PO_{4}$ + 12 NADP +

The net reaction of $C_{3}$ dark fixation is 6RuBP + $6CO_{2}$ + 18ATP + 12 NADPH + 6 RuBP + $C_{6}H_{12}O_{6}$ + 18 ADP + 18P + 12NADP+

Answer: (c)

Answer: (d)

Answer: (a)

Crassulacean acid metabolism (CAM) is photosynthesis by the $C_4$ pathway in which carbon- dioxide is taken up during the night, when the plant's stomata are open and fixed into malic acid. During the day, when the stomata are closed, carbon dioxide is released from malic acid for use in the Calvin cycle. This is important for plants that live in arid conditions as it enables them to keep their stomata closed during the day to reduce water loss from evaporation. Crassulacean acid metabolism is common in succulent plants of desert regions, including cacti and spurges and in certain ferns.

Answer: (a)

Answer: (b)

Answer: (c)

The light dependent production of ATP from ADP + Pi in the chloroplasts is called photophosphorylation. Photophosphorylation is of 2 types – Cyclic photophosphorylation – It involves only PS-I, water is not utilised and so no oxygen is evolved. Here two ATP molecules are produced. Non-cyclic photophosphorylation – It involves both PS-I and PS-II, water is utilised and so oxygen is evolved. Here one ATP molecule and one $NADPH_2$ molecule are produced.

Answer: (a)

Answer: (d)

Carotenoids of higher plants are fat soluble compound that includes carotenes and xanthophylls. Most of them absorb light of violet and blue range. Green light is absorbed in less amount.

Answer: (b)

Chemiosmotic hypothesis has been put forward by Mitchell (1961) to explain the mechanism of ATP synthesis.

Answer: (a)

Manganese ($Mn^{2+}$) is used for photolysis of water to produce oxygen and electrons during light reaction of photosynthesis. It is the phenomenon of breaking up of water into hydrogen and oxygen in the illuminated chloroplast. It acts as an essential cofactor.

Answer: (b)

Photosystem II has almost equal number of chlorophyll a and chlorophyll b molecules. It is darkgreen in colour and located mostly in the appressed parts of grana thylakoids towards the inner surface of membranes.

Answer: (b)

Answer: (a)

Answer: (a)

In leaves of C4 plants, malic acid synthesis during C$O_{2}$fixation occurs in mesophyll cells. The mesophyll cells per form $C_{4}$ cycle and the cells of bundle sheath perform $C_{3}$ cycle.

Answer: (d)