Photosynthesis in ${\mathrm{C}}_4$ plants is relatively less limited by atmospheric ${\mathrm{CO}}_2$ levels because
1. The primary fixation of ${\mathrm{CO}}_2$ is mediated via PEP carboxylase.
2. Effective pumping of ${\mathrm{CO}}_2$ into bundle sheath cells.
3. Four carbon acids are the primary initial ${\mathrm{CO}}_2$ fixation products.
4. RuBisCO in ${\mathrm{C}}_4$ plants has higher affinity for ${\mathrm{CO}}_{2.}$

During photorespiration, the oxygen consuming reaction (s) occur in
1. Stroma of chloroplasts and mitochondria
2. Stroma of chloroplasts and peroxisomes
3. Grana of chloroplasts and peroxisomes
4. Stroma of chloroplasts

The chemiosmotic coupling hypothesis of oxidative phosphorylation proposes that adenosine triphosphate (ATP) is formed because
1. there is a change in the permeability of the inner mitochondrial membrane toward adenosine diphosphate (ADP)
2. high energy bonds are formed in mitochondrial proteins
3. ADP is pumped out of the matrix into the intermembrane space
4. a proton gradient forms across the inner membrane

Read the following four statements a, b, c and d and select the right option having both correct statements:
(a) Z scheme of light reaction takes place in presence of PS I only
(b) Only PS I is functional in cyclic photophosphorylation
(c) Cyclic photophosphorylation results into synthesis of ATP and NADPH
(d) Stroma lamellae lack PS II as well as NADP reductase
Options :
1. (c) and (d)
2. (b) and (d)
3. (a) and (b)
4. (b) and (c)

In Kranz anatomy, the bundle sheath cells have
1. thick walls, many intercellular spaces and few chloroplasts
2. thin walls, many intercellular spaces and no chloroplasts
3. thick walls, no intercellular spaces and large number of chloroplasts
4. thin walls, no intercellular spaces and several chloroplasts

With reference to factors affecting the rate of photosynthesis, which of the following statements is not correct?
1. Increasing atmospheric ${\mathrm{CO}}_2$ concentration up to 0.05 % can enhance ${\mathrm{CO}}_2$ fixation rate
2. ${\mathrm{C}}_3$ plants respond to higher temperatures with enhanced photosynthesis while ${\mathrm{C}}_4$ plants have much lower temperature optimum
3. Tomato is a greenhouse crop which can be grown in ${\mathrm{CO}}_2$ – enriched atmosphere for higher yield
4. Light saturation for ${\mathrm{CO}}_2$ fixation occurs at 10% of full sunlight

Assertion: Not all organisms use carbon dioxide as a source of carbon atoms to carry out photosynthesis.
Reason: Photoheterotrophs use organic compounds, rather than carbon dioxide, as a source of carbon.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: The Calvin cycle in most plants occurs during daylight.
Reason: None of the steps of the Calvin cycle require light directly

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false

Assertion: Action spectrum of photosynthesis is much broader than the absorption spectrum of chlorophyll a.
Reason: Accessory pigments with different absorption spectra are also present in chloroplasts.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.