Each human egg and sperm cell carries 23 chromosomes, so a fertilized zygote has 46.
Correct Answer
True
True. Each parent contributes 23 chromosomes, giving the zygote 23 pairs, or 46 in all, so half of a person's genetic material comes from each parent.
Category: Genetics and Evolution
Question 2
A recessive trait is expressed whenever a person carries just one copy of the recessive allele.
Correct Answer
False
False. A recessive trait appears only when a person has two copies of the recessive allele; with one copy, a dominant allele masks it.
Category: Genetics and Evolution
Question 3
Height and skin color are examples of polygenic traits, which are influenced by many genes.
Correct Answer
True
True. Polygenic traits are controlled by multiple genes, which is why they vary along a continuum rather than falling into a few distinct categories.
Category: Genetics and Evolution
Question 4
Under natural selection, organisms that are poorly suited to their environment are the most likely to survive and reproduce.
Correct Answer
False
False. Natural selection, described by Charles Darwin, favors organisms that are better suited to their environment, which survive and reproduce more and pass on their genes.
Category: Genetics and Evolution
Question 5
A mutation is a sudden, permanent change in a gene.
Correct Answer
True
True. Mutations are lasting changes in genetic material; most are harmful or neutral, but an occasional beneficial one supplies the variability that natural selection acts on.
Category: Genetics and Evolution
Question 6
Glial cells support neurons by providing structure, insulation and transport of nutrients and waste.
Correct Answer
True
True. Glia are the support cells of the nervous system; they hold neurons in place, form myelin, move nutrients and waste, and help with immune responses.
Category: Neurons and Synapses
Question 7
The axon carries a neural signal toward the cell body.
Correct Answer
False
False. The axon carries the signal away from the cell body toward the terminal buttons; dendrites are the branches that carry incoming signals toward the cell body.
Category: Neurons and Synapses
Question 8
Once a neuron reaches threshold, its action potential travels down the axon at full strength without fading.
Correct Answer
True
True. This is the all-or-none principle: a neuron either fires completely or not at all, and once started the action potential keeps its full strength along the axon.
Category: Neurons and Synapses
Question 9
An antagonist drug mimics a neurotransmitter and activates its receptor.
Correct Answer
False
False. An antagonist blocks or impedes a neurotransmitter at its receptor; a drug that mimics a neurotransmitter and activates the receptor is an agonist.
Category: Neurons and Synapses
Question 10
The parasympathetic division returns the body to routine resting functions after a threat has passed.
Correct Answer
True
True. The parasympathetic division slows the heart, constricts the pupils and stores glucose, reversing the arousal produced by the sympathetic division.
Category: Nervous System Divisions
Question 11
Afferent nerve fibers carry motor commands away from the central nervous system to the muscles.
Correct Answer
False
False. Afferent fibers carry sensory information toward the central nervous system; efferent fibers carry motor commands away from it to the muscles.
Category: Nervous System Divisions
Question 12
The central nervous system consists of the brain and the spinal cord.
Correct Answer
True
True. The brain and spinal cord make up the central nervous system, while the nerves that connect it to the rest of the body form the peripheral nervous system.
Category: Nervous System Divisions
Question 13
Each cerebral hemisphere controls movement on the same side of the body.
Correct Answer
False
False. Each hemisphere controls the opposite side of the body, so the left hemisphere controls the right side and the right hemisphere controls the left side.
Category: Cerebral Cortex
Question 14
The corpus callosum is a thick band of axons that connects the left and right hemispheres.
Correct Answer
True
True. The corpus callosum lets the two hemispheres share information; cutting it, as in split-brain surgery for severe epilepsy, prevents that communication.
Category: Cerebral Cortex
Question 15
The somatosensory cortex, which processes touch, temperature and pain, is located in the occipital lobe.
Correct Answer
False
False. The somatosensory cortex lies in the parietal lobe; the occipital lobe contains the primary visual cortex.
Category: Cerebral Cortex
Question 16
The amygdala is involved in emotional experience and in attaching emotional meaning to memories.
Correct Answer
True
True. The amygdala is a limbic structure that processes emotions such as fear and links emotional significance to memories.
Category: Brain Structures
Question 17
The cerebellum regulates body temperature and appetite.
Correct Answer
False
False. The hypothalamus regulates body temperature and appetite; the cerebellum coordinates balance, movement and motor skills.
Category: Brain Structures
Question 18
An EEG measures brain activity with very precise timing but locates that activity less precisely than an fMRI does.
Correct Answer
True
True. EEG electrodes on the scalp track electrical activity millisecond by millisecond, which makes EEG useful for studying sleep, but they give only a rough picture of where the activity comes from. fMRI shows location in much finer detail.
Category: Brain Imaging
Question 19
A spinal reflex, such as pulling a hand away from a hot stove, must be processed by the brain before the movement occurs.
Correct Answer
False
False. Spinal reflexes are handled by the spinal cord itself without waiting on the brain, which is what makes these protective responses so fast.
Category: Nervous System Divisions
Question 20
Compared with neurotransmitters, hormones take effect more quickly and their effects end sooner.
Correct Answer
False
False. Hormones travel through the bloodstream, so their effects are slower to begin and longer lasting than the effects of neurotransmitters acting at synapses.
Category: Endocrine System