Multiple Choice QuestionsVelamen 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.
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.
D.
If both assertion and reason are false.
C4 plants are those plants that produce C4 compound like malic acid or aspartic acid as the first stable compound of CO, fixation cycle, eg. maize. sugar cane etc. These plants can grow in dense tropical, forests where there is poor supply of CO2 because there is internal supply of CO2 Also photorespiration is negligible or absent in these plants. So, they are photosynthetically more efficient than C3 plants. These plants show a special type of leaf anatomy called Kranz anatomy. C4 plants uses mesophyll cells and bundle sheath cells in the outer part of their leaves. The C4 pathway shows 2 carboxylation reactions one in mesophyll chloroplast and the other in bundle sheath. Chloroplasts- CO2 acceptor is PEP and not RuBP and PEP carboxylase is the key enzyme.
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
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