Plant Biology — Common Exam Question Types

1.Common question: which of the following occurs in the stroma, the thylakoid membrane, or the thylakoid lumen?

2.Answer: Water splitting that releases oxygen happens in the thylakoid lumen. Electron transport chain happens in the thylakoid membrane. Hydrogen ion accumulation happens in the thylakoid lumen. ATP synthesis happens at the membrane with ATP released to the stroma. Calvin cycle and carbon fixation happen in the stroma. NADPH is produced on the stroma side.

3.Common question: which adaptation helps plants survive in hot, dry environments?

4.Key features. Opening stomata at night equals CAM plants. PEP carboxylase in mesophyll cells equals C4 plants. Storing malate in vacuoles equals CAM. Calvin cycle compartmentalized in bundle-sheath cells equals C4.

5.Common question: what is the primary force driving water transport in xylem?

6.Answer: transpiration pull combined with cohesion of water molecules. Transpiration at the leaf creates negative pressure that pulls the water column up; hydrogen bonds between water molecules keep the column intact.

7.Common question: which was the first adaptation enabling life on land?

8.Answer: cuticle and stomata — solving the desiccation problem. Cuticle is a waxy layer preventing water loss; stomata allow controlled gas exchange.

9.Common question: how might transgenes escape from GMO crops to wild populations, and how can we prevent it?

10.Three escape routes. One: pollen drift via wind or insect pollination carries GMO pollen to wild relatives. Two: seed dispersal mixes GMO seeds with non-GMO. Three: horizontal gene transfer to soil microorganisms — rare but theoretically possible.

11.Four prevention methods. One: GURT, also called terminator technology, makes GMO seeds sterile. Two: maternal inheritance — insert the transgene into chloroplast DNA, since pollen does NOT carry chloroplasts. Three: physical isolation with buffer zones. Four: temporal isolation by staggering flowering times.

12.Year one thirteen essay focus: chloroplast transformation is the most elegant answer — since pollen almost never carries chloroplast DNA, the transgene cannot spread through pollen.