Hummingbirds vary in appearance among related species. The diagram shows two hummingbirds, P and Q, that represent different species.

Living cells cannot use heat to provide the activation energy for biochemical reactions because which choice(s) complete the sentence correctly? a) answer choice ii. eliminate b) answer choices ii and iv. c) answer choice iii and iv. d) all answers can complete the sentence.

Match each description to the appropriate biome. tropical savanna desert tropical rain forest taiga tundra has sparse vegetation and very cold temperatures located near the equator and contains trees that form dense canopy layers is very hot and dry, and has plants that need little water has cold winters, heavy snowfall and is dominated by conifers has warm temperatures and is dominated by grasses

As the human population grows, what happens to our natural-resource requirements? o they increase o they decrease o they do not change. they go in cycles