8.4.2 Regions of the human brain and brain imaging: MRI, fMRI, PET and CT Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 8

The 20 questions

1. Which region of the brain is mainly responsible for conscious thought, voluntary movement and sensory perception?

   • Cerebral hemispheres, including the cortex, which control conscious thought, voluntary movement and sensory processing
   • Medulla oblongata, which controls involuntary functions such as breathing, heart rate and the diameter of blood vessels
   • Hypothalamus, which regulates body temperature, thirst and the release of hormones from the pituitary
   • Cerebellum, which co-ordinates balance, posture and the timing of smooth voluntary movements

2. Which region of the brain co-ordinates balance and smooth movement?

   • Medulla oblongata, which contains the cardiovascular and ventilation centres that control involuntary functions
   • Cerebellum, which co-ordinates voluntary movements, balance and posture
   • Hypothalamus, which monitors the internal environment and controls the release of hormones from the pituitary
   • Pons, a region of the brainstem that relays signals between the cerebrum and the cerebellum but does not control movement

3. Which region of the brain controls involuntary processes such as heart rate and breathing rate?

   • Cerebral cortex, which controls conscious decisions and voluntary actions across the whole body
   • Cerebellum, which co-ordinates the timing of voluntary movements and maintains posture and balance
   • Corpus callosum, which connects the two cerebral hemispheres and transfers information between them
   • Medulla oblongata, which contains the cardiovascular and ventilation centres that control heart rate and breathing

4. Which region of the brain controls body temperature, thirst and the release of hormones from the pituitary?

   • Medulla oblongata only, which controls breathing and heart rate and has no role in hormone release
   • Cerebellum, which co-ordinates balance and the smooth timing of voluntary movement across the limbs
   • Hypothalamus, which monitors temperature and thirst and controls the pituitary gland through nerve and hormone signals
   • Cerebral hemispheres, which control conscious thought, memory and voluntary action across the cortex

5. Which imaging technique uses X-rays taken from many angles to produce cross-sectional images?

   • Functional MRI (fMRI), which detects changes in blood oxygenation to show which regions of the brain are active
   • Positron emission tomography (PET), which detects gamma rays from a radioactive tracer to show metabolic activity
   • Magnetic resonance imaging (MRI), which uses strong magnetic fields and radio waves to build detailed soft-tissue images
   • Computed tomography (CT), which rotates an X-ray source around the body and combines many images into cross-sections

6. Which technique uses a strong magnetic field and radio waves to align and detect hydrogen nuclei in the body?

   • Ultrasound, which uses high-frequency sound waves that echo from the boundaries between tissues
   • MRI, which uses strong magnetic fields and radio waves to detect signals from hydrogen nuclei in water and fat
   • CT, which uses X-rays and detects how much radiation is absorbed by the tissues of the body
   • PET only, which uses radioactive tracers and does not involve any magnetic field or radio waves

7. Which imaging technique uses a radioactive tracer that emits positrons to show metabolic activity?

   • Electroencephalography, which records the electrical activity of the brain through electrodes on the scalp
   • PET, which detects gamma rays produced when positrons from a tracer annihilate, showing metabolic activity
   • MRI, which uses magnetic fields to produce high-resolution images of soft tissue in the body
   • CT, which uses X-rays to produce images of the bones and internal organs of the body

8. Which advantage does MRI have over CT for imaging soft tissue?

   • MRI can only image bone, which makes it less useful than CT for showing the soft tissues of the body
   • MRI gives better contrast of soft tissues and does not use ionising radiation, unlike CT
   • MRI is faster than any other technique, so it is always preferred in emergency situations for every injury
   • MRI uses ionising radiation to give better contrast in soft tissue than CT does for the same region

9. What does fMRI measure to show brain activity?

   • Gamma rays from a radioactive tracer, which are emitted by the active regions of the brain during a task
   • The electrical charge on bone, which varies with the activity of the nerves in the nearby tissues
   • Changes in blood oxygenation, which reflect neuronal activity, since active regions use more oxygen
   • The concentration of sodium in the cerebrospinal fluid, which rises when neurones are active in a region

10. Which statement describes a disadvantage of PET scanning?

    • It cannot be used on the brain, since the tracer does not reach the cerebral tissues in sufficient amounts
    • It involves exposure to radioactive material, so the dose must be controlled and the scans are limited
    • It takes images without any tracer, which means the results are less accurate than those from other scans
    • It does not show any metabolic activity, so it gives no information about the function of the tissue

11. A patient has a tumour pressing on the cerebellum. Which symptom would be most consistent with this?

    • Loss of hormone secretion from the pancreas, since the cerebellum signals the pancreas to release insulin
    • Increased heart rate only, since the cerebellum controls the cardiovascular system directly
    • Failure of the kidney to filter the blood, since the cerebellum controls the rate of urine production
    • Loss of balance and co-ordination, since the cerebellum is needed for smooth and balanced movement

12. A patient has damage to the medulla oblongata. Which function is most likely affected?

    • Growth of long bones, since the medulla controls the release of growth hormone from the pituitary
    • Language understanding only, since the medulla is the centre of language processing in the brain
    • Skin colour, since the medulla controls the production of melanin in the skin of the body
    • Breathing and heart rate, since the medulla contains the centres that control these involuntary functions

13. Which imaging technique would be best for detecting a fracture of the skull?

    • fMRI, which shows changes in blood oxygenation and is used to detect activity in the brain
    • PET, which uses radioactive tracers to show metabolic activity in the body tissues
    • CT, which shows bone detail clearly and is well suited to identifying fractures of the skull
    • Electroencephalogram only, which records electrical activity from the scalp and cannot show bone

14. Which imaging technique would be most useful for showing which region of the brain is active while a person reads a passage?

    • Ultrasound of the abdomen, which uses sound waves to show the organs in the abdominal cavity
    • fMRI, which detects changes in blood oxygenation that reflect neural activity during a task such as reading
    • CT, which uses X-rays to show the structure of the bones and soft tissues of the head
    • Chest X-ray, which shows the structures of the lungs and heart but not the brain at all

15. A student compares CT and MRI. Which conclusion is best supported?

    • CT uses X-rays and is good for bone, while MRI uses magnetic fields and gives detailed soft-tissue images
    • CT uses no radiation, whereas MRI uses X-rays to produce images of the soft tissues
    • MRI shows only the blood flow in the heart, whereas CT shows the structure of the whole brain
    • CT and MRI are identical in every way, since both use the same physical principle to build images

16. A PET scan shows high uptake of a glucose-based tracer in one region of the brain. What does this suggest?

    • That region is made of bone, since bone is the only tissue that takes up glucose tracers in the body
    • That region has high metabolic activity, since glucose uptake is greatest where cells use the most energy
    • That region has no blood supply, since the tracer cannot reach any tissue that is supplied by blood
    • That region has low metabolic activity, since the tracer is taken up only by inactive tissue

17. Which statement about the cerebral hemispheres is correct?

    • They are the site of conscious thought, memory and voluntary movement, and are divided into two halves
    • They are located in the spinal cord, which connects the brain to the rest of the body through the nerves
    • They produce insulin for the pancreas, since the hemispheres control the endocrine glands in the body
    • They control only involuntary functions such as heart rate, which are regulated by the cortex alone

18. Which of the following best explains why MRI can show soft tissue in more detail than CT?

    • MRI uses higher energy X-rays than CT, which penetrate soft tissue more effectively to show its structure
    • MRI detects only calcium in bones, which makes the soft tissue around the bones easy to see in the images
    • MRI relies on the different relaxation times of hydrogen nuclei in different tissues, which gives contrast between them
    • MRI measures the sound produced by the brain, and different tissues produce different sounds that are recorded

19. A researcher wants to show which regions are active during a memory task, without using radiation. Which technique is most suitable?

    • X-ray, which shows the bones of the skull but gives no information about the activity of the brain
    • fMRI, which detects changes in blood flow and oxygenation without ionising radiation, so it can be repeated
    • CT, which uses X-rays to build images of the brain structure and is suitable for repeated use in studies
    • PET with a radioactive tracer, which shows the activity of the brain but requires a radioactive dose each time

20. Which evaluation is best for the claim that a brain scan can fully explain a person's thoughts?

    • Correct, because all scans show exact thoughts in the form of images that can be read without any interpretation
    • Incorrect, because scans show no information about the brain, so they cannot be used to study any function at all
    • Incorrect, because scans show activity and structure, and interpretation of patterns is needed, so they cannot fully explain thoughts alone
    • Correct, because all brain regions have a fixed single function, so any scan can read the thought directly

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