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Questions in biology

[Done] In the context of classical conditioning, which of the following statements is true of habituation? A. It refers to the weakening of a conditioned response when the unconditioned stimulus is absent. B. It refers to the decreased responsiveness to a stimulus after repeated presentations. C. It is the process of learning to respond to certain stimuli and not others. D. It is the process by which a conditioned response can recur after a time delay, without further conditioning

[Done] Which is a primary sexual characteristic?

[Done] What is the purpose of a control group in an experiment? A. To ensure that all variables are held constant B. To provide a standard of comparison C. To manipulate the independent variable D. To observe the effects of the dependent variable

[Done] Select the best answer for the question. 7. Fish respiratory systems exchange gas and receive oxygen at the gills. This oxygen then enters the blood stream and is pumped through the heart and back through the gills without first returning to the heart. This order of events best describes which type of circulation system? A. Recycling B. Open C. Double loop D. Single loop

[Done] Impulses travel over the synapse through which of the following? A. axon terminals B. neurotransmitters C. myelin sheaths D. Schwann cells

[Done] Which is a key component of the energy molecule ATP? A. sodium B. phosphorus C. chlorine D. sulfur

[Done] The relationship between bacteria and legumes that results in nitrogen is best described as A. parasitic B. mutualistic C. commensalistic D. none of the above

[Done] Fiona puts her hands into a sinkful of lukewarm water; Luke puts his hands into a sinkful of ice-cold water. Based on what is known about neural transmission, you could predict that the action potentials will: A. be weaker in Fiona's system because the stimulus is less intense B. be the same in both individuals due to the all-or-none principle C. travel a shorter distance in Luke's system because the stimulus is more intense D. travel more quickly in Luke's system because the stimulus is more intense

[Done] Which term refers to variables that are kept constant in an experiment? A. Independent variables B. Dependent variables C. Controlled variables D. Experimental variables

[Done] The carbon cycle ensures that carbon is not lost. Which is another important benefit of the carbon cycle? A. The carbon cycle helps regulate Earth's temperature. B. The carbon cycle ensures that living things have a continual source of hydrogen. C. The carbon cycle helps transport nutrients in bodies of water. D. The carbon cycle ensures that there is a continual supply of water.