there are many changes that happen on the molecular level when a plant experiences stress. when in heat shock, for example, their protein molecule structures become unstable, unfold, or reconfigure to become less efficient. membrane stability will decrease in plastids, which is why photosynthesis is the first process to be affected by heat stress. despite the many stresses, xerophytes have the ability to survive and thrive in drought conditions due to their physiological and biochemical specialties.