Question

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in NADPH production in the chloroplasts. (Interestingly, reduction of NAD+ to NADH in the mitochondria is unaffected). Given this observation, which of the following changes would occur in these plants

(1) 3-PGA levels would increase
(2) RuBP levels would decrease
(3) The plant's ability to make glucose would increase

Answer 1

(1) is the correct option

Step-by-step explanation:

• Calvin cycle reduces atmospheric CO2 in 3-C sugar with the use of ATP AND NADPH,which produced in light reaction
• Reaction of Calvin cycle can be divided in three stages:
• Carboxylation, Reduction and Regeneration
• In carboxylation,reaction is catalysed by RuBISCO and RuBP is the CO2 acceptor forming 2 molecules of 3-PGA (first stable intermediate)
• Reduction of 3-PGA to glyceraldehyde 3 phosphate occurs using NADPH and ATP
• Regeneration of CO2 acceptor (RuBP) from glyceraldehyde 3 phosphate occurs
• If there is decrease in level of NADPH then it won't be used up during reduction step and hence 3 PGA will not convert into glyceraldehyde 3 phosphate and therefore level of 3 PGA will increase