A substance that enters Earth's cycles and does harm to living things is

a. a pollutant.

b. hydrogen.

c. freshwater.

d. oxygen.

When water used to cool machinery is returned to a river, it raises the river water temperature. this causes a sharp decline in small invertebrate populations. based on the food web, a likely consequence of this change would be?

Arrange the phases in the life cycle of the Sun in order from the birth of the Sun to the time in the far distant future when the Sun has cooled. Phases: becomes a black dwarf. becomes a white dwarf. begins nuclear fusion at its core.

What must happen for a solar eclipse to occur? A) The moon must be full. B) The moon must pass behind Earth. C) The moon's orbit must cross the plane of the ecliptic. D) The moon's orbit must not cross Earth's penumbra.

Some species of marine annelids that are closely related to lugworms do not have gills. Based on your understanding of basic physiological principles, do you expect the gill-less species to be smaller or larger than the lugworm species that

Why would scientists collect species that they are studying

Drag and drop each phrase to show whether it describes a pond or a lake. sunlight reaches the bottom Pond Lake small and shallow plant growth throughout no plant growth on the bottom deep and cold Sunt does not reach bottom

What is a leading cause of death for paddlers in small crafts such as canoes kayaks and rafts boat ed?

How would a change in the sequence of nucleotides in a DNA molecule affect the mRNA transcribed from the DNA molecule?

Which planet rotates most slowly about it axis

What is an advantage of using cell culture rather than bacterial culture to produce biological molecules?