Velamen present in orchids helps in

• absorption of nutrients from host plant

• respiration

• absorption of moisture from air

• synthesising food

Assertion: The higher concentration of O₂ in the atmosphere is inhibitory to photosynthesis.

Reason: CO₂ is the main substrate of photosynthesis.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

203.

Assertion : Dark reaction is purely enzymatic reaction.

Reason : It occurs only in absence of light.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

What is common between chloroplasts, chromoplasts and leucoplasts

• Presence of pigments

• Possession of thylakoids and grana

• Storage of starch, proteins and lipids

• Ability to multiply by a fission-like process

Assertion: Under conditions of high light intensity and limited CO₂ supply,
photorespiration has a useful role in protecting the plants from photo-oxidative damage.

Reason: If enough CO₂ is not available to utilize light energy for carboxylation to proceed, the excess energy may not cause damage to plants.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: Photosynthetically C₄ plants are less efficient than C3 plants.

Reason: The operation of C₄ pathway requires the involvement of only bundle-sheath cells.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is falsen

• If both assertion and reason are false.

The sugarcane plant has

• dumb-bell shaped guard cells

• pentamerous flowers

• reticulate venation

• capsular fruits.

Assertion : C₄ photosynthetic pathway is more efficient than the C₃ pathway.

Reason : Photorespiration is suppressed in C₄ plants.

• If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion

• If both Assertion and Reason are true but the Reason is not the correct explanation of the assertion

• If Assertion is true but Reason is false

• If both Assertion and Reason are false

Assertion : The atmospheric concentration of CO₂ at which photosynthesis just compensates for respiration is referred to as CO₂ compensation point. 

Reason : The CO₂ compensation point is reached when the amount of CO₂ uptake is less than that generated through respiration because the level of CO, in the atmosphere is more than that required for achieving CO₂ compensation point.

• If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion

• If both Assertion and Reason are true but the Reason is not the correct explanation of the assertion

• If Assertion is true but Reason is false

• If both Assertion and Reason are false

Photorespiration in C₃ plants starts from:

• phosphoglycerate

• phosphoglycolate

• glycerate

• glycine