Photosynthesis — Set 1
Biology · प्रकाश संश्लेषण · Questions 1–10 of 50
Which pigment is primarily responsible for capturing light energy during photosynthesis?
Correct Answer: D. Chlorophyll a
Chlorophyll a is the essential pigment that initiates the light-dependent reactions. It absorbs energy from blue and red light waves efficiently. Other pigments act as accessory molecules to transfer energy to it.
During the process of photosynthesis, oxygen is released as a byproduct of which event?
Correct Answer: A. Splitting of water
The splitting of water molecules, known as photolysis, releases oxygen into the atmosphere. This reaction occurs within the thylakoid membranes of the chloroplast. It provides the necessary electrons to replace those lost by chlorophyll.
In which part of the chloroplast do the dark reactions (Calvin cycle) take place?
Correct Answer: C. Stroma
The stroma is the fluid-filled space where enzymes fix carbon into sugar. It contains the necessary rubisco enzyme for the Calvin cycle. This stage is independent of direct light but requires products from light reactions.
Which gas is absorbed by plants from the atmosphere to perform photosynthesis?
Correct Answer: A. Carbon dioxide
Plants take in carbon dioxide through small openings called stomata. This gas provides the carbon atoms needed to build organic glucose molecules. Increased levels of this gas can sometimes enhance the rate of photosynthesis.
What is the primary sugar produced as a result of photosynthesis?
Correct Answer: C. Glucose
Glucose is the simple carbohydrate formed during the final stages of the process. It serves as the primary energy source for the plant's growth and cellular activities. Excess glucose is generally converted into starch for long-term storage.
Which metal ion is found at the center of the chlorophyll molecule?
Correct Answer: D. Magnesium
Magnesium is the central atom in the porphyrin ring of the chlorophyll molecule. Its presence is vital for the pigment's ability to absorb solar energy. A deficiency of this mineral leads to yellowing of leaves, known as chlorosis.
The light-dependent reactions of photosynthesis occur specifically in the?
Correct Answer: D. Thylakoid membranes
Light-dependent reactions take place in the thylakoids where pigments are embedded. These reactions convert solar energy into chemical energy stored in ATP and NADPH. These structures are often stacked into columns called grana.
Which of the following colors of light is least effective for photosynthesis?
Correct Answer: C. Green
Green light is mostly reflected or transmitted by chlorophyll rather than absorbed. This reflection is why most plant leaves appear green to the human eye. Red and blue light provide the highest energy absorption for the process.
The first stable product of the Calvin cycle in C3 plants is?
Correct Answer: B. Phosphoglyceric acid (PGA)
The correct answer is 'Phosphoglyceric acid (PGA)'. In C3 plants, the first stable intermediate is a three-carbon molecule called 3-PGA. This occurs when carbon dioxide combines with RuBP under the influence of rubisco. Most common agricultural crops like wheat and rice are C3 plants.
Which enzyme is the most abundant protein on Earth and helps in carbon fixation?
Correct Answer: C. Rubisco
Rubisco facilitates the reaction between carbon dioxide and RuBP in the stroma. It plays a critical role in bringing inorganic carbon into the biological food chain. Despite its importance, it is relatively slow and inefficient in its catalytic activity.