Why are two photosystems necessary?

How can you tell that the green sum on a pond is a plant

How long is my arm?

Which causes a sea breeze? Air temperatures are cooler than normal. Air flows from the poles toward the equator. Air blows over long distances at different speeds. Air above land warms quicker than air over water.

Why is insertion/deletion of three bases less deleterious than insertion/deletion of one or two bases.

Drew currently walks two miles every day after school but wants to take his workout to the next level. Which of these changes would you suggest he make to his routine to increase his stamina? A. Walk before school instead of after B.

10. What is a genotype? A an organism's combination of genes for a trait B an organism's appearance as a result of its genes C the ratio of dominant to recessive genes in an individual D the collection of dominant genes in an organism

How much of a person's weight is water?

What are the two components of the central nervous system in vertebrates?

A river has a large amount of algae growing. Which most likely caused the growth?

Which of the following statements is true? Natural energy sources are nonrenewable and being depleted. Current fuels are not polluting the air. Mercury released into aquatic ecosystems comes from rock erosion.