Which option correctly pairs a biotic stress with an abiotic stress exemplar?

• A. Biotic: drought; Abiotic: aphid infestation.
• B. Biotic: aphid infestation; Abiotic: drought.
• C. Biotic: salinity; Abiotic: disease.
• D. Biotic: temperature extremes; Abiotic: weed competition.

Answer: (B)

The main idea here is telling apart stresses caused by living organisms from those caused by non-living environmental factors. Biotic stresses come from pests, pathogens, or any living organism that harms the plant. Abiotic stresses come from non-living conditions like water shortage, high salinity, or extreme temperatures.

Aphid infestation is a living organism causing damage, so it’s a biotic stress. Drought is a lack of water, an environmental condition that isn’t caused by any living creature, so it’s abiotic. Pairing these two makes sense: living pest pressure with a non-living water stress.

The other options mix the categories: drought is abiotic (not biotic) even when paired with something living; disease is a biotic factor but is paired with an abiotic one in those cases; salinity and temperature extremes are abiotic, while weed competition is a biotic factor.