Biology Test Biology Ecology and Evolution 3

Question 1

What is the primary source of energy for most ecosystems on Earth?

Accepted Answer

Solar energy captured by photosynthesis

Answer

Photosynthetic organisms (plants, algae, cyanobacteria) convert solar energy into chemical energy, forming the energetic foundation of most food webs.

Question 2

Which type of speciation occurs when a physical barrier geographically separates a population?

Accepted Answer

Allopatric speciation

Answer

Allopatric speciation occurs when a population is divided by a geographic barrier, preventing gene flow and allowing the groups to diverge into separate species.

Question 3

In a food web, what is the effect of removing a keystone predator?

Accepted Answer

The prey population explodes, destabilizing the ecosystem

Answer

Without the keystone predator, prey populations grow unchecked (trophic cascade), often overgrazing or outcompeting other species and reducing biodiversity.

Question 4

Which biogeochemical cycle involves bacteria converting atmospheric nitrogen into forms usable by plants?

Accepted Answer

Nitrogen cycle

Answer

In the nitrogen cycle, nitrogen-fixing bacteria convert atmospheric N₂ into ammonia (NH₃), which plants can absorb and use to build proteins.

Question 5

What does 'r-selected' reproductive strategy describe in ecology?

Accepted Answer

Species that produce many offspring with little parental investment

Answer

r-selected species maximize reproductive rate by producing many offspring with minimal parental care, thriving in unstable or unpredictable environments.

Biology Practice Test Practice Test

Biology Practice Test Practice Test

Biology Test Biology Ecology and Evolution 3