Psych 301, Fall ’03 Exam 3 Practice Questions 1. What is the relationship between genes and alleles? a. There are typically multiple possible alleles for a given gene. b. There are typically multiple possible genes for a given allele. c. A gene is a connected series of alleles that work together. d. An allele is a connected series of genes that work together. 2. A dominant allele is one that a. leads to aggressive behavior in the individual. b. determines the phenotype regardless of the identity of its partner on the matching chromosome. c. needs to be present on both chromosomes in a pair in order to affect the phenotype. d. directs the action of other genes on the same chromosome. 3. What is the relationship between dominant and recessive alleles? a. The dominant allele directs the activity of the recessive allele. b. In a given individual, the dominant allele is active most of the time and the recessive allele is active only part of the time. c. The recessive allele has no effect on the phenotype if it is paired with a dominant allele. d. Both alleles exert an effect, but the dominant allele’s is more pronounced. 4. Eye color is largely determined by a single gene. The allele for blue eyes is recessive and the allele for brown eyes is dominant. What can be said of someone who is heterozygous for this gene? a. They necessarily have brown eyes. b. They necessarily have blue eyes. c. They have one brown eye and one blue eye (a rare condition in people but one that is common in many breeds of dog). d. There is not enough information to determine their eye color. 5. A polygenic trait a. is affected by many genes. b. is affected by a single gene for which there are many possible alleles. c. is one that differs significantly across racial groups. d. is one for which there are no dominant alleles. 6. The process of producing gametes, cells that have only one set of chromosomes, is called a. mitosis b. meiosis c. differentiation d. discrimination 7. The heritability of a trait refers to a. the probability that it will be passed on to an offspring. b. the proportion of that trait (e.g. the fraction of total IQ points) that is due to genes. c. the proportion of variation across individuals along that trait dimension that is due to variation in genes. d. none of the above. 8. The heritability coefficient is affected by a. genetic diversity in the population under study. b. environmental (experiential) diversity in the population under study. c. neither. d. both. 9. Which of these is not part of a neuron? a. dendrite b. axon c. soma d. synapse 10. Terminal buttons are located a. at the ends of axons b. on the soma c. on glial cells d. at the ends of dendrites 11. Afferent signals are a. signals that determine emotion (affect). b. incoming signals. c. signals that serve only to modify the effects of other signals. d. outgoing signals. 12. The sodium-potassium pump a. sends ions up and down the axon. b. moves ions across the synapse. c. is important in the digestion of proteins. d. moves ions across the cell membrane. 13. The resting potential of a neuron a. is negative. b. is positive. c. is negative in inhibitory cells and positive in excitatory cells. d. is zero. 14. A neuron’s membrane potential is a. its potential for generating electrical charge by allowing ions to pass across its membrane. b. affected by neurotransmitters released by other cells. c. the difference in electrical charge between the inside and the outside of the cell. d. both b and c. 15. All of the following are true about excitatory signals except a. they decrease the polarization of the cell (membrane potential moves towards zero). b. they increase the probability of an action potential. c. they are often triggered by the neurotransmitter GABA. d. they often work by allowing sodium (Na+) into the cell. 16. What is the correct sequence of events during an action potential? a. sodium (Na+) enters the cell, the cell depolarizes, potassium (K+) leaves the cell, the cell repolarizes b. potassium (K+) enters the cell, the cell depolarizes, sodium (Na+) leaves the cell, the cell repolarizes c. sodium (Na+) leaves the cell, the cell depolarizes, potassium (K+) enters the cell, the cell repolarizes d. potassium (K+) leaves the cell, the cell depolarizes, sodium (Na+) enters the cell, the cell repolarizes 17. The threshold for an action potential refers to a. the peak amount of charge that it can carry. b. the amount of depolarization required for it to be triggered. c. the amount of hyperpolarization required for it to be triggered. d. the number of times the action potential must occur before it leads to neurotransmitter being released from the terminal buttons. 18. The all-or-none principle of action potentials refers to the fact that a. when an action potential reaches the terminal button, the cell releases all of its stored neurotransmitters or it releases none. b. at any given moment, either every neuron in the brain is firing or none of them are. c. every action potential is the same size; the cell cannot partially fire. d. a cell must receive excitatory signals from all of its incoming synapses before it can generate an action potential. 19. A refractory period a. is a time when action potentials can travel in the opposite direction down an axon. b. is a time when an action potential cannot happen. c. typically lasts about 1 second. d. is the delay between when a neuron fires and when it absorbs more oxygen from the blood (as measured by PET of fMRI). 20. Which of the following is true about myelin sheaths? a. They insulate the dendrites of a neuron. b. They increase the traveling speed of action potentials. c. They are the reason that grey matter looks grey. d. They are constructed from blood vessels.21. Receptors for neurotransmitters are located in a. the synapse. b. the axon of the pre-synaptic cell. c. the membrane of the post-synaptic cell. d. the brain only. 22. Ionotropic receptors a. also act as ion channels. b. have only indirect effects on membrane potentials. c. are located on the pre-synaptic cell. d. respond to the neurotransmitters Na+ and/or K+ (sodium and potassium ions). 23. Which of the following is a possible action of a dopamine agonist?
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