What types of cells does HIV infect?
A. basophils and killer T cells
B. B cells and red marrow cells
C. helper T cells and macrophages
D. liver cells and cardiac muscle cells
E. epithelial cells and eosinophils
Answer: C
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In an experiment on the effects of deforestation of a portion of a northern temperate deciduous forest, all the trees were removed from a small mountainside watershed area and herbicides were applied for three years to prevent regrowth. Measurements of the concentration of calcium (an important nutrient) in runoff water were taken both before and after the deforestation. Monthly measurements also were made in a similar watershed in another part of the same forest that had been left undisturbed. The findings are displayed in the graph below. (There is an image in your packet #101-105) 2002 test Which of the following factors affecting the hydrologic cycle would have the LEAST impact on calcium loss from the disturbed watershed?
(A) Total precipitation (B) Surface runoff (C) Evaporation (D) Transpiration (E) Porosity of soil
Which of the following is NOT a feature associated with filtration?
A) nitrocellulose or plastic membrane filters B) sterilization of heat-sensitive materials C) varying thicknesses of membrane filters used D) use of HEPA filters to filter air E) ability of some filters to trap viruses and proteins
The advantages of a four-chambered heart is that it __________
a. prevents mixing of oxygenated and deoxygenated blood b. prevents deoxygenated blood from entering the heart c. allows better flow of blood to the tissues d. prevents mixing of oxygenated and deoxygenated blood and allows tissues to be bypassed e. prevents mixing of oxygenated and deoxygenated blood and allows better flow of blood to the tissues
When a stimulus is applied to a receptor in the skin, an action potential is propagated along a neuron to the brain, where another signal is sent back to the muscle for a response. Which of the following best describes what occurs when the action potential reaches a chemical synapse at the end of an axon?
(A) The action potential jumps from one axon to the next connecting axon. (B) The action potential travels through the synapse to the next connecting dendrite. (C) The action potential jumps the synapse to the next connecting dendrite. (D) The action potential causes a release of neurotransmitters that travel across the synapse.