Question

trophic levels & energy transfer
(herbivores)
tertiary consumers
10 kcal/m²/year
the vast majority of energy
is lost as heat to the
environment. said heat is
produced by cellular
respiration, a necessary
function for life.
secondary consumers
100 kcal/m²/year
(carnivores)
only about 10% of a levels
absorbed energy is absorbed
by the next one
primary consumers
(omnivores)
1000 kcal/m²/year
primary producers
10,000 kcal/m²/year
(autotrophs)
decomposers live off energy by
decomposing dead and solid matter
from the other trophic levels
decomposers
(saprotrophs)
○ addition or removal of a top predator causes a ripple effect that changes the entire
food web
○ removing all decomposers to eliminate a food web
○ humans cannot affect the energy available in an ecosystem at all

Explanation:

1. For the first option: In an ecosystem, top predators (tertiary consumers here) are keystone species. Removing or adding them disrupts the food web (e.g., trophic cascade), causing ripple effects. This matches ecological principles.
2. Second option: Decomposers are vital for nutrient cycling. Removing all decomposers would collapse the ecosystem, not "eliminate a food web" as a valid action, and it's ecologically unsound.
3. Third option: Humans affect ecosystems (e.g., deforestation, pollution) which impacts energy flow (e.g., reducing producers affects energy available to higher levels), so this is false.

Answer:

A. addition or removal of a top predator causes a 'ripple effect' that changes the entire food web