Photosynthesis Quiz - ICSE Class 10 Biology
Free practice quiz: Photosynthesis (ICSE Class 10 Biology). 46 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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Which of the following molecules is the primary electron acceptor in the light-dependent reactions of photosynthesis?
- ATP
- NADP+
- Glucose
- Water
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Answer: B. NADP+
During the light-dependent reactions, light energy is used to split water molecules and excite electrons. These high-energy electrons are then passed along an electron transport chain, ultimately reducing NADP+ to NADPH. NADPH is a crucial electron carrier that will be used in the Calvin cycle to reduce carbon dioxide into sugars.
Which of the following is NOT a pigment involved in photosynthesis?
- Chlorophyll a
- Carotenoids
- Anthocyanins
- Chlorophyll b
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Answer: C. Anthocyanins
Chlorophyll a and b are the primary photosynthetic pigments. Carotenoids are accessory pigments that absorb light in different wavelengths and transfer energy to chlorophyll. Anthocyanins are water-soluble pigments that often contribute to the red, purple, or blue colors of plant tissues but are not directly involved in capturing light energy for photosynthesis.
The enzyme catalyzing the reduction of NADP+ to NADPH in the light-dependent reactions is located in:
- The stroma of the chloroplast
- The lumen of the thylakoid
- The thylakoid membrane
- The inner mitochondrial membrane
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Answer: C. The thylakoid membrane
The enzyme NADP+ reductase, which catalyzes the final step of electron transfer to NADP+ to form NADPH, is embedded within the thylakoid membrane. The electrons are passed to it from the electron transport chain, and NADP+ is reduced on the stromal side of the membrane.
The bundle sheath cells in C4 plants are characterized by:
- High concentrations of PEP carboxylase and low concentrations of RuBisCO.
- High concentrations of RuBisCO and low concentrations of PEP carboxylase.
- Equal concentrations of PEP carboxylase and RuBisCO.
- Absence of both PEP carboxylase and RuBisCO.
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Answer: B. High concentrations of RuBisCO and low concentrations of PEP carboxylase.
In C4 plants, the spatial separation of carbon fixation ensures that the Calvin cycle occurs in bundle sheath cells. These cells are rich in RuBisCO, the enzyme that fixes CO2 into the Calvin cycle, and are generally low in PEP carboxylase, which is primarily found in the mesophyll cells.
Which statement is true regarding the relationship between chlorophyll and accessory pigments in light absorption?
- Accessory pigments absorb light energy and pass it to chlorophyll a, broadening the absorption spectrum.
- Chlorophyll a is the only pigment that absorbs light directly.
- Accessory pigments are located in the stroma, while chlorophyll is on the thylakoid membrane.
- Accessory pigments are more efficient than chlorophyll a in converting light energy to chemical energy.
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Answer: A. Accessory pigments absorb light energy and pass it to chlorophyll a, broadening the absorption spectrum.
Accessory pigments, such as carotenoids and chlorophyll b, absorb light energy at wavelengths that chlorophyll a cannot absorb efficiently. They then transfer this absorbed energy to chlorophyll a molecules in the reaction centers, thereby increasing the overall efficiency of light capture during photosynthesis.