Why is sunlight the source for all food energy in an ecosystem?

What unit of time on Earth is based on the revolution of the Earth around the Sun? A. Day B. Hour C. Year D. Month

Which of the following forces is responsible for keeping the planets in orbit around the Sun? A. electromagnetic force B. friction C. gravity D. magnetism

Describe in detail how gases are exchanged between the respiratory system and the circulatory system in the lungs

The burning of coal and oil for energy affects the carbon cycle in which way? A. It increases the amount of carbon in existence. B. It decreases the amount of carbon in existence. C. It increases the amount of atmospheric carbon. D.

Many bacterial infections of the lower digestive tract are treated with

Who used a compound microscope to see chambers within a cork and name them cells

What is the force of resistance acting between objects in contact and tending to dampen their motion? options: 1. gravity 2. sliding force 3. friction 4. electromagnetic force

Which of the following describes a relationship of commensalism? A. A tapeworm latches itself in the intestines of a rat, feeding off all the nutrients eaten by the rat. B. Oxpecker Birds eat parasitic tricks off the backs of zebras C.

Which of these statements about osmosis and active transport is NOT correct? A) Both endocytosis and active transport require cell energy. B) Osmosis requires cell energy while active transport does not.

Which of the following two cycles are the most closely related in their role in sustaining life?