MCAT Biology : Brain and Central Nervous System

Study concepts, example questions & explanations for MCAT Biology

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Example Questions

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Example Question #72 : Nervous System And Nervous Tissue

An individual presents to his physician with an abnormal breathing rhythm. The physician suspects that the problem may be originating from his brain. What part of his brain is most likely not functioning properly?

Possible Answers:

Hypothalamus

Cerebellum

Hippocampus

Medulla oblongata

Midbrain

Correct answer:

Medulla oblongata

Explanation:

The medulla oblongata is responsible for autonomic functions, such as breathing rate and heart rate regulation. Dysfunction of the medulla oblongata could result in problems with breathing rhythm.

The cerebellum is responsible for coordination and balance. The hypothalamus regulates the fight-or-flight response, sex drive, thirst, and hunger. The midbrain is the center for auditory and visual signal relay to the cortex. The hippocampus functions in the retention of memories.

Example Question #73 : Nervous System And Nervous Tissue

Which of the following structures connects the right and left hemispheres of the brain?

Possible Answers:

Mammillary Body

Stria terminalis

Olfactory bulb

Hypothalamus

Corpus collosum

Correct answer:

Corpus collosum

Explanation:

The MCAT contains minimal questions regarding brain anatomy, however, you should have an understanding of a select few structures, one of which is the corpus collosum. The corpus collosum is a bundle of neurons connecting the left and right brain, allowing communication between the left and right hemispheres. If these neurons were damaged somehow, the result would be split-brain syndrome, a condition in which the two halves of the brain do not communicate with one another.

Example Question #1 : Brain And Central Nervous System

Which of the following activities would you expect to be controlled by the cerebral cortex?

Possible Answers:

Memory

Breathing while asleep

Salivation

Heart rate

Correct answer:

Memory

Explanation:

The cerebral cortex is also referred to as the "higher brain." It acts to process thoughts and store memories. More basic, vital activities such as heart beat and breathing are controlled by other, less developed regions of the brain. Note that the hippocampus plays a role in creating memories, but most memories are stored in the cerebrum; this is the link between long term and short term memory storage.

Example Question #75 : Nervous System And Nervous Tissue

Which part of the brain is responsible for controlling body temperature, and adjusting to external temperature conditions?

Possible Answers:

Hypothalamus

Cerebellum

Cerebrum

Thalamus

Correct answer:

Hypothalamus

Explanation:

The hypothalamus is responsible for cooling and heating mechanisms in the body, and thus is the correct answer. 

The cerebrum is responsible for higher brain functions, like conscious thought. The cerebellum is essential for balance and coordination. The thalamus is primarily responsible for integrating and coordinating sensory input to the brain.

Example Question #2 : Brain And Central Nervous System

An individual presents to his physician with a complaint of "uncoordinated muscle movements." After running proper tests, the physician suspects that this individual has some degree of brain injury. Which portion of the brain is most likely to be injured?

Possible Answers:

Midbrain

Medulla oblongata

Hypothalamus

Hippocampus

Cerebellum

Correct answer:

Cerebellum

Explanation:

The cerebellum is responsible for coordination and balance. Injury to the cerebellum can result in a loss of motor coordination.

The medulla oblongata controls autonomic activities, such as regulating heart and respiration rates. The hypothalamus regulates the fight-or-flight response, sex drive, thirst, and hunger. The midbrain is the center for auditory and visual signal relay to the cortex. The hippocampus functions in the retention of memories.

Example Question #3 : Brain And Central Nervous System

A lesion to which brain region would result in a lack of coordinated movement?

Possible Answers:

The hypothalamus

The left temporal lobe

The cerebellum

The medulla oblongata

Correct answer:

The cerebellum

Explanation:

The cerebellum is responsible for the coordination of movement between the motor and sensory cortices. It helps account for movements and correct the magnitude of stimulation of skeletal muscle. The cerebellum is essential for fine-tuning functions like balance and hand-eye coordination.

The medulla, or medulla oblongata, is mainly responsible for the modulation of involuntary vital functions like ventilation rate and heart rate. The hypothalamus plays a key role in the activation of the sympathetic nervous system and also plays a key role in hunger, sexual reproduction, and endocrine function. The temporal lobe is a region of the cerebrum, and is associated with auditory and speech function as well as memory formation.

Example Question #3 : Brain And Central Nervous System

Which section of the brain is responsible for regulating temperature?

Possible Answers:

Medulla

Limbic system

Cerebrum

Frontal cortex

Hypothalamus

Correct answer:

Hypothalamus

Explanation:

Receptors in the hypothalamus regulate temperature by sending nerve signals to muscles and sweat glands in the body. The hypothalamus is located deep within the center of the brain, at the very top of the brain stem. The other answers are different sections of the brain responsible for other tasks. For instance, the cerebrum is the largest section of the brain responsible for memory, consciousness, language and intellect.

Example Question #5 : Brain And Central Nervous System

Which of the following is part of the hindbrain?

Possible Answers:

Cerebellum

Cerebrum

Thalamus

Hypothalamus

Broca's area

Correct answer:

Cerebellum

Explanation:

The hindbrain consists of the pons, medulla oblongata, and cerebellum.

The cerebrum, thalamus, and hypothalamus are part of the forebrain. Broca's area is a specific region of the cerebrum dedicated to understanding language.

Example Question #80 : Nervous System And Nervous Tissue

Which of the following accurately describes white matter?

Possible Answers:

White matter features the cell bodies of the neurons in the spinal cord

White matter is denser than gray matter

White matter consists of myelinated axons in the central nervous system

White matter is located in the central part of the spinal cord and is surrounded by gray matter

White matter is only found in the peripheral nervous system

Correct answer:

White matter consists of myelinated axons in the central nervous system

Explanation:

White matter refers to the white-colored myelin that surrounds the axons of neurons in the central nervous system. These axons are grouped together, creating distinct regions of white matter. In contrast, grey matter refers to the cell bodies of neurons in the central nervous system. The cell bodies are packed together into dense regions to create grey matter.

In a cross-section of the spinal cord, gray matter is located in the center and is surrounded by white matter.

Example Question #141 : Systems Biology And Tissue Types

Which is the correct order of sequences during the knee-jerk reflex?

Possible Answers:

Patella tendon stretches – spinal cord – sensory neuron – motor neuron – quadriceps contract

Quadriceps stretch – sensory neuron – spinal cord – motor neuron – patella tendon contracts

Patella tendon stretches – motor neuron – spinal cord – sensory neuron – quadriceps contract

Patella tendon stretches – sensory neuron – spinal cord – motor neuron – quadriceps contract

Patella tendon stretches – sensory neuron – spinal cord –brain – motor neuron – quadriceps contract (reflex bypasses the brain)

Correct answer:

Patella tendon stretches – sensory neuron – spinal cord – motor neuron – quadriceps contract

Explanation:

During the knee-jerk reflex, the neural signal is initiated by the stretching of the patella tendon, which is transmitted via sensory neuron to the spinal cord. In turn, the signal is transmitted to the motor neuron, resulting in the contraction of quadriceps. Most importantly, the reflex bypasses the brain, allowing a speedy reaction of the body to the stimulus. 

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