Two different versions of the same gene, such as one coding for a cleft chin and one for a smooth chin, are called what?
Alleles
✓
Chromosomes
Phenotypes
Nucleotides
Correct Answer
Alleles
Alleles are alternative forms of a single gene, and a person inherits one from each parent. Chromosomes are long strands of DNA that carry many genes. Phenotypes are the observable traits that result from genes and environment. Nucleotides are the building blocks that make up DNA.
Category: Genetics and Evolution
Question 2
A man inherited one allele for a cleft chin from his mother and one for a smooth chin from his father. Which term describes his genotype for this trait?
Homozygous dominant
Heterozygous
✓
Homozygous recessive
Polygenic
Correct Answer
Heterozygous
Heterozygous means having two different alleles for a gene, written Bb. Homozygous dominant would mean two dominant alleles (BB). Homozygous recessive would mean two recessive alleles (bb). Polygenic describes a trait controlled by many genes, not a person's allele pair for one gene.
Category: Genetics and Evolution
Question 3
Why has the allele for sickle-cell anemia persisted in regions where malaria is common?
People with two copies are immune to malaria
The allele is dominant over the normal allele
Carriers with one copy are protected against malaria
✓
The allele arises anew from mutation in every generation
Correct Answer
Carriers with one copy are protected against malaria
People who carry one copy of the sickle-cell allele show few symptoms and are protected against malaria, so they survive and reproduce more often where malaria is common. People with two copies are immune to malaria is wrong, because they develop sickle-cell anemia and gain no malaria immunity. The allele is dominant over the normal allele is wrong, because sickle-cell anemia requires two copies. The allele arises anew from mutation in every generation is wrong, because it persists through inheritance and natural selection.
Category: Genetics and Evolution
Question 4
Which concept holds that genes set the limits of a person's potential while the environment determines where within those limits the person ends up?
Epigenetics
Natural selection
Genetic-environmental correlation
Range of reaction
✓
Correct Answer
Range of reaction
Range of reaction describes genes as setting upper and lower boundaries and the environment as determining where a person falls between them. Epigenetics studies how environment changes gene expression. Natural selection is the process by which better-suited organisms survive and reproduce more. Genetic-environmental correlation describes genes and environment influencing each other in both directions.
Category: Genetics and Evolution
Question 5
Which part of a neuron consists of branching extensions that receive incoming signals from other neurons?
Dendrites
✓
Axon
Terminal buttons
Myelin sheath
Correct Answer
Dendrites
Dendrites branch out from the cell body and receive messages from other neurons. The axon carries the signal away from the cell body. Terminal buttons at the end of the axon release neurotransmitters. The myelin sheath insulates some axons and speeds transmission.
Category: Neurons and Synapses
Question 6
Which structure, formed by glial cells, insulates some axons and speeds the transmission of neural signals?
Synaptic cleft
Myelin sheath
✓
Soma
Dendrite
Correct Answer
Myelin sheath
The myelin sheath is a fatty coating made by glial cells that wraps some axons and lets signals travel faster; its loss in multiple sclerosis disrupts signaling. The synaptic cleft is the gap between neurons. The soma is the cell body that holds the nucleus. A dendrite is a branch that receives signals.
Category: Neurons and Synapses
Question 7
What is the approximate resting potential of a typical neuron?
-55 mV
+30 mV
-70 mV
✓
0 mV
Correct Answer
-70 mV
At rest the inside of a neuron is about 70 millivolts more negative than the outside, because of uneven ion concentrations across the membrane that the sodium-potassium pump helps keep in place. -55 mV is roughly the threshold that must be reached to trigger an action potential. +30 mV is roughly the peak of an action potential. 0 mV would mean no charge difference across the membrane.
Category: Neurons and Synapses
Question 8
When a neuron's membrane potential reaches threshold, channels open that let which ions rush into the cell?
Potassium ions
Chloride ions
Calcium ions
Sodium ions
✓
Correct Answer
Sodium ions
Reaching threshold opens sodium channels, and positively charged sodium ions flood in, driving the membrane potential up into an action potential. Potassium ions flow out afterward, returning the cell to a negative charge. Chloride ions are not the ions that drive the rising phase. Calcium ions matter at the terminal buttons for neurotransmitter release, not for the rising phase along the axon.
Category: Neurons and Synapses
Question 9
After a neurotransmitter is released, leftover molecules in the synapse are pumped back into the neuron that released them. What is this process called?
Reuptake
✓
Repolarization
Myelination
Summation
Correct Answer
Reuptake
Reuptake clears neurotransmitter from the synaptic cleft by returning it to the sending neuron, where it can be reused. Repolarization is the return of the membrane to a negative charge after an action potential. Myelination is the formation of the myelin sheath around axons. Summation is the adding together of incoming signals at a neuron.
Category: Neurons and Synapses
Question 10
How do SSRI medications, often prescribed for depression, change the activity of serotonin?
They block its receptors
They keep it in the synapse longer
✓
They break it down in the synapse
They stop its release from the neuron
Correct Answer
They keep it in the synapse longer
SSRIs are selective serotonin reuptake inhibitors, so they slow the pumping of serotonin back into the sending neuron and leave more of it in the synapse. They block its receptors describes an antagonist, which would reduce serotonin's effect. They break it down in the synapse would lower serotonin, the opposite of the goal. They stop its release from the neuron would also reduce serotonin signaling.
Category: Neurons and Synapses
Question 11
Parkinson's disease is associated with the degeneration of dopamine-producing cells in which brain structure?
Reticular formation
Hippocampus
Substantia nigra
✓
Amygdala
Correct Answer
Substantia nigra
The substantia nigra produces dopamine that is critical for movement, and its degeneration causes the motor symptoms of Parkinson's disease. The reticular formation regulates arousal and the sleep-wake cycle. The hippocampus is a forebrain structure involved in learning and memory. The amygdala is a forebrain structure involved in emotion.
Category: Brain Structures
Question 12
A hiker who suddenly spots a bear feels her heart race and her pupils dilate. Which part of the nervous system is producing these changes?
Parasympathetic nervous system
Somatic nervous system
Enteric nervous system
Sympathetic nervous system
✓
Correct Answer
Sympathetic nervous system
The sympathetic division of the autonomic nervous system prepares the body for fight or flight by raising heart rate, dilating the pupils and releasing glucose. The parasympathetic nervous system does the opposite, returning the body to rest. The somatic nervous system controls voluntary movement and senses. The enteric nervous system governs the digestive tract, not the whole-body alarm response.
Category: Nervous System Divisions
Question 13
Which part of the peripheral nervous system carries the signals for voluntary movements such as typing on a keyboard?
Somatic nervous system
✓
Autonomic nervous system
Sympathetic nervous system
Parasympathetic nervous system
Correct Answer
Somatic nervous system
The somatic nervous system relays sensory information to the central nervous system and carries motor commands to skeletal muscles for voluntary actions. The autonomic nervous system controls organs and glands outside voluntary control. The sympathetic nervous system is the autonomic branch that drives the stress response. The parasympathetic nervous system is the autonomic branch that restores rest and routine functioning.
Category: Nervous System Divisions
Question 14
After a stroke, a patient understands speech well but struggles to produce spoken words. Damage to which brain area best explains this pattern?
Wernicke's area
Broca's area
✓
Occipital lobe
Cerebellum
Correct Answer
Broca's area
Broca's area in the frontal lobe is essential for producing language, so damage there makes speaking very difficult while comprehension can remain. Wernicke's area damage impairs understanding of language instead. The occipital lobe processes vision. The cerebellum coordinates balance and movement rather than language production.
Category: Cerebral Cortex
Question 15
Where in the brain is the primary visual cortex located?
Temporal lobe
Parietal lobe
Occipital lobe
✓
Frontal lobe
Correct Answer
Occipital lobe
The primary visual cortex sits in the occipital lobe at the back of the brain. The temporal lobe contains the auditory cortex and is involved in hearing and memory. The parietal lobe processes body senses such as touch and pain. The frontal lobe handles reasoning, motor control and language production.
Category: Cerebral Cortex
Question 16
Which brain structure acts as a sensory relay station for every sense except smell?
Hypothalamus
Hippocampus
Pons
Thalamus
✓
Correct Answer
Thalamus
Information from all the senses except smell passes through the thalamus before being sent on to other brain areas for processing. The hypothalamus regulates homeostatic functions such as body temperature and appetite. The hippocampus is involved in learning and memory. The pons connects the hindbrain to the rest of the brain and helps regulate sleep.
Category: Brain Structures
Question 17
Damage to which brain structure is most likely to disrupt automatic functions such as breathing, heart rate and blood pressure?
Medulla
✓
Cerebellum
Hippocampus
Occipital lobe
Correct Answer
Medulla
The medulla, at the base of the brainstem, controls automatic processes such as breathing, heart rate and blood pressure. The cerebellum coordinates balance and movement. The hippocampus supports learning and memory. The occipital lobe processes visual information.
Category: Brain Structures
Question 18
Which gland is often called the master gland because its hormones regulate the activity of other endocrine glands?
Thyroid
Pituitary
✓
Adrenal
Pineal
Correct Answer
Pituitary
The pituitary, at the base of the brain, releases messenger hormones that control other endocrine glands, though it largely follows instructions from the hypothalamus. The thyroid regulates metabolism and appetite. The adrenal glands release epinephrine and norepinephrine in the stress response. The pineal gland secretes melatonin, which regulates some biological rhythms.
Category: Endocrine System
Question 19
People with diabetes do not produce enough of which pancreatic hormone, which normally lowers blood glucose?
Glucagon
Thyroxine
Insulin
✓
Melatonin
Correct Answer
Insulin
Insulin from the pancreas lowers blood sugar by helping cells take in glucose, and diabetes involves too little of it. Glucagon is also made by the pancreas but raises blood glucose. Thyroxine is a thyroid hormone that regulates metabolism. Melatonin is a pineal hormone involved in sleep rhythms.
Category: Endocrine System
Question 20
A split-brain patient sees a picture of a key flashed only to the left visual field. What is the patient typically able to do?
Name the key aloud
Draw the key with the right hand
Write the word key with the right hand
Draw the key with the left hand
✓
Correct Answer
Draw the key with the left hand
The left visual field sends information to the right hemisphere, which controls the left hand, so the patient can draw the object with the left hand. Name the key aloud fails because speech depends on the left hemisphere, which never received the image once the corpus callosum is cut. Draw the key with the right hand fails because the right hand is controlled by the left hemisphere. Write the word key with the right hand fails for the same reason.
Category: Cerebral Cortex