This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Chloroplast Structure and Function – Light Absorption”.
1. Energy absorbed from sunlight is stored as chemical energy in which of the following biomolecules?
a) ATP, ADP
b) ATP, NADPH
c) NAD, FAD
d) NADH2, ATP
Explanation: Energy from sunlight is absorbed and saved in the form of chemical energy in two types of biomolecules in plants namely ATP and NADPH. ATP is the cell’s primary source of energy and NADPH is the cell’s primary source of reducing power.
2. Which types of molecules are synthesized in light-independent (dark) reactions?
d) nucleic acids
Explanation: The second stage of events involved in photosynthesis is referred to as light-independent (dark) reactions. In these carbohydrates are synthesized from carbon dioxide using energy stored in ATP and NADPH.
3. Photon of light of higher wavelength has _____________ energy.
Explanation: Energy of photons are inversely proportional to the wavelength given by the formula E=hv. So the light having lower wavelength will have higher energy and vice verse.
4. Pigments absorb light of particular wavelengths.
Explanation: Pigments are compounds that appear visibly colored because they only absorb light of particular wavelengths. Chlorophyll is a green colored pigment found in chloroplasts of plants.
5. Which part of the chlorophyll is responsible for absorption of light?
a) hydrophobic phytol chain
b) porphyrin ring
c) thylakoid membrane
d) outer membrane
Explanation: Chlorophyll has two parts; porphyrin ring and hydrophobic phytol chain. Porphyrin ring functions in the absorption of light and the hydrophobic phytol chain maintains the integration of chlorophyll in photosynthetic chain.
6. Which atoms are present in the porphyrin of a chlorophyll molecule?
Explanation: In myoglobin and hemoglobin the porphyrins contain iron (heme groups) whereas porphyrins present in chlorophyll contain magnesium atom.
7. What are carotenoids?
b) cell organelles
c) terrestrial plants
d) granulated thylakoids
Explanation: Carotenoids are accessory light-absorbing pigments found in terrestrial plants. β-carotene is a carotenoid. These pigments absorb in blue and green regions of the spectrum.
8. Carotenoids dissipate absorbed energy as heat.
Explanation: Carotenoids function as secondary light absorbers during photosynthesis and draw excess away from excited chlorophyll molecules (to prevent the formation of singlet oxygen) to dissipate it as heat.
9. Which of the following type of spectrum is a plot of efficiency of different types of wavelengths in bringing about the photosynthesis?
a) absorption spectrum
b) action spectrum
c) efficiency spectrum
d) reflection spectrum
Explanation: Action spectrum is a plot of relative rate of photosynthesis induced by lights of different wavelengths. The spectrum identifies wavelengths that are effective in inducing a physiological response.
10. Which of the following contains a linear system of conjugated double bonds?
Explanation: β-carotene is a carotenoid, a pigment that acts as accessory light absorber during photosynthetic reaction. It has a linear system of conjugated double bonds.
Sanfoundry Global Education & Learning Series – Cell Biology.
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