Question

The Aristidoideae subfamily of grasses inhabits arid regions and respire using the C4 photosynthetic pathway. A related grass, Axonopus compressus, grows in moist, shaded environments and photosynthesizes using the more common C3 photosynthetic pathway. What is a possible explanation for the difference in respiration? (2 points) Question 14 options: 1) The grasses coevolved different respiratory mechanisms of the same species in different environments. 2) The grasses evolved as a result of biotic stresses. 3) The grasses evolved different respiratory methods to adapt to the differences in water availability of their environments. 4) The grasses evolved similar respiratory methods due to their common cellular structures.

Answer 1

Answer 3 is the most correct choices. The difference in respiration is a result of adaptation to differences in water availability in their environments. In a more arid area, a different photosynthetic pathway would be needed because the air is more dry and most likely has a lesser amount of rainfall. In contrast, a moist, shaded environment would use the more commo C3 photosynthetic pathway because the air is more moist and most likely has a higher amount of rainfall.