Question

which of the following is not a possible effect of rising carbon dioxide levels on plants?
a. increased photosynthesis
b. increased plant mortality
c. increased crop productivity
d. increased plant growth

please select the best answer from the choices provided

a
b
c
d

Explanation:

• Option A: Carbon dioxide is a reactant in photosynthesis. Higher levels can increase the rate of photosynthesis as plants have more of this key reactant, so this is a possible effect.
• Option B: Rising CO₂ levels generally have positive or neutral direct effects on plant physiology (like increased photosynthesis, growth, productivity). Increased plant mortality is not a typical direct effect of rising CO₂ on plants (other stressors like temperature changes or pests might cause mortality, but CO₂ itself doesn't directly increase mortality; it often benefits plant growth/photosynthesis/productivity).
• Option C: With increased photosynthesis (due to more CO₂), plants can produce more biomass, which can lead to increased crop productivity (though other factors like nutrient availability can limit this, but it is a possible effect).
• Option D: More photosynthesis means more energy and resources for the plant, which can lead to increased plant growth, so this is a possible effect.

Answer:

B. Increased plant mortality