Question

C3, C4 and CAM plants have advantages and disadvantages under specific environmental conditions. In theory a hybrid plant carrying all three mechanisms would have the largest flexibiliy to respond and do well under various conditions

Indicate what steps should be activated or turned off during the following environmental conditions and motivate that on an energy level and water loss how that optimizes photosynthetic yield:

i. 10^oC night temperature, 30^oC day temperature, dry ground, high light intensity

ii. 10^oC night temperature, 15^oC day temperature, wet ground, high light intensity

iii. 10^oC night temperature, 40^oC day temperature, wet ground, high light intensity

iv. 10^oC night temperature, 40^oC day temperature, dry ground, high light intensity

Answer 1

In C3 plants, photosynthesis is less efficient in high light and temperature conditions. C3 plants will outcompete C4 in wet areas. CAM plant grow in xerophytic condition.C3 plants require an optimum temperature range of 18 – 24oC. C4 plants require an optimum temperature range of 30 – 40oC.Cam plants can tolerate higher temperatures.CAM has photosynthetic cycle similar to C4. Only difference is low water requirement and tolerance to very hih temperature.Based on these informations we can infer the following

i. 10oC night temperature, 30oC day temperature, dry ground, high light intensity

30oC day temperature,dry ground and high light intensity favours C4 over C3 so C3 will be shut. 30oC day temperature favours C4 over Cam , so C3 and CAM will shut down , C4 will remain on.

ii. 10oC night temperature, 15oC day temperature, wet ground, high light intensity

wet ground means CAM needs to be shut down .15oC day temperature favours C3 so C4 will shut down, C3 will be on but photorespiration will lead to energy loss

iii. 10oC night temperature, 40oC day temperature, wet ground, high light intensity

wet ground means CAM needs to be shut down. 40oC day temperatureand  high light intensity favours C4. So C3 will shut down , C4 will be on.

iv. 10oC night temperature, 40oC day temperature, dry ground, high light intensity

40oC day temperature,dry ground and high light intensity favours CAM over C3 & C4, so C3 & C4 will be shut. CAM will remain on