Photosynthesis — Set 5
Biology · प्रकाश संश्लेषण · Questions 41–50 of 50
During photosynthesis, the energy from ATP is used to fix ______.?
Correct Answer: A. Carbon
ATP provides the required energy to convert inorganic carbon dioxide into organic sugar. This occurs during the reduction phase of the Calvin cycle. Without this energy input, the conversion of carbon would be impossible.
What is the role of NADPH in the Calvin cycle?
Correct Answer: A. Provide electrons/hydrogen
NADPH acts as a reducing agent by donating electrons and hydrogen ions to the carbon intermediates. This reduction step is essential for forming high-energy sugar molecules. It is produced during the non-cyclic light-dependent pathway.
Which of the following is the correct chemical equation for photosynthesis?
Correct Answer: C. 6CO2 + 6H2O -> C6H12O6 + 6O2
The correct answer is '6CO2 + 6H2O -> C6H12O6 + 6O2'. The standard equation shows six molecules of CO2 and water reacting to form glucose and oxygen. Light energy is the catalyst that drives this endergonic reaction forward. This represents a perfect balance of matter and energy transformation.
The thickness of the leaf's cuticle primarily helps to?
Correct Answer: A. Reduce water loss
The waxy cuticle prevents excessive transpiration, ensuring the plant has enough water for photosynthesis. This is especially important for plants living in sunny or windy conditions. It also provides a barrier against pathogens and physical damage.
Which of the following structures connects two grana in a chloroplast?
Correct Answer: B. Stroma lamellae
Stroma lamellae are tubular membranes that connect the stacked grana together. They play a role in separating the two photosystems and facilitating energy transfer. They also ensure the structural integrity of the internal chloroplast membrane system.
Photosynthesis occurs in which layer of the leaf's internal structure?
Correct Answer: D. Mesophyll
The mesophyll layer contains the highest density of chloroplast-rich cells. It is divided into palisade and spongy layers to optimize light capture and gas exchange. This tissue is specifically adapted to be the primary factory for sugar production.
What is the primary function of guard cells in a leaf?
Correct Answer: A. Open and close stomata
Guard cells change shape based on water pressure to control the size of stomatal pores. This allows the plant to balance the need for CO2 with the risk of dehydration. They are the only epidermal cells that contain chloroplasts.
The red and purple colors of some leaves and fruits are due to?
Correct Answer: C. Anthocyanins
Anthocyanins are water-soluble vacuolar pigments that appear red, purple, or blue. They protect tissues from ultraviolet light and help attract pollinators or seed dispersers. Unlike chlorophyll, they are not directly involved in the light-harvesting process.
Which of the following is produced during the light reaction and used in the dark reaction?
Correct Answer: D. ATP and NADPH
ATP and NADPH are the chemical link between the light-dependent and light-independent stages. They provide the energy and electrons required to reduce CO2 into sugar. They are synthesized in the thylakoid and utilized in the stroma.
In deep-sea environments, some organisms use chemicals instead of light to make food in a process called?
Correct Answer: C. Chemosynthesis
Chemosynthesis uses the energy from chemical reactions, such as hydrogen sulfide, to produce organic matter. This allows life to thrive in complete darkness near hydrothermal vents. It is a vital alternative to photosynthesis in extreme ecosystems.