Which blood vessels have thin walls and contain valves?

A. Veins

B. Capillaries

C. Arteries

D. Platelets

How many DNA molecules would there be after four DNA molecules unzip and replicate?

Two organism that are classfied in the same class will always be classfied in the same A. genus B. family c. phylum D. order

Water is warmed by the sun and

What is the name of the particle that circles the nucleus of an atom?

Which of the following is not an observation or inference on which natural selection is based A. Population produces more offsprings than environment is able to support B.

How does a vascular plant's phloem differ from its xylem? A. Phloem is found only in the leaves. B. Only phloem transports water. c. Only water flows through phloem. D. Phloem has a two-way flow of materials,

Many mutations have been identified in the lac operon. A particular mutation prevents the repressor protein from binding to the operator under all circumstances.

What is the independent variable in this experiment? A) temperature B) Number of chirps C) Number of crickets D) Location of the laboratory

The parents of a client with a mental illness being cared for at home tell the nurse that they have been feeling overwhelmed lately. they say, "we need to get away for a few days to recharge ourselves.

Explain how the conversion of wetlands to farmland has impacted streams and rivers.