Distinguishing pyramid of biomass from pyramid of numbers in a parasitic food chain

Steps:

• Outline the chain: grass (producers, high biomass/many individuals) → cows (few, high biomass) → insects (many small parasites, low biomass) → birds (few, low biomass).
• Define pyramid of numbers: shows organism counts per trophic level; inverted here between cows (few) and insects (many).
• Define pyramid of biomass: shows total dry mass per level; upright as mass decreases upward, with insects' low mass despite high numbers.
• Match diagrams: upright shape (1) fits biomass; inverted shape (3) fits numbers.

Why A is correct:

• A assigns 1 (upright) to biomass, matching the 10% energy transfer rule where standing crop mass decreases up trophic levels, and 3 (inverted) to numbers due to parasitic abundance.

Why the others are wrong:

• B: Swaps assignments; biomass cannot be inverted as total mass always decreases.
• C: 4 likely upright or irregular, not matching inverted numbers from insect proliferation.
• D: 3 as biomass wrongly inverts mass; 2 likely doesn't show insect peak.

Final answer: A