Homeostasis Practice Questions (2018+) Flashcards
Scientists investigated the effect of drinking ice-cold water on:
* internal body temperature
* the rate of sweating
Give the reason why the person should not move during the investigation
- movement would release (extra) heat
- movement would increase body temperature
- movement would increase sweating
How does the thermoregulatory centre send information to sweat glands in
the skin?
via nerve(s) / neurones
or
via (nerve) impulse(s)
The results show that when the ice-cold water was drunk, the temperature near
the brain decreased.
Explain why the temperature near the brain decreased
blood is cooled at stomach / mouth
(cooled) blood flows to the brain
The rate of sweating changes between 24 minutes and 36 minutes.
Explain how this change helps to maintain the person’s normal body
temperature.
less sweating occurs
so less heat is lost or less cooling
What happens to the volume of water lost as sweat when a person runs a
marathon?
(volume) increases
Blood entering the kidneys goes through the process of
___________________
Glucose is not found in urine because of __________________
Urine is removed from the body in the process of _________________
filtration
reabsorption
excretion
Describe the advantages and disadvantages of having a kidney transplant
instead of having dialysis
- no need for regular / long hospital visits or is a long-term
solution - flexible lifestyle, such as can go on holidays
- may not live near a hospital or reference to transport costs
- no risk of infection from frequent needles / treatment
- less / no need to control diet
- maintains correct concentration of substances in blood / body
- cheaper long term for NHS / hospital
Disadvantages of kidney transplant - may be rejected
- have to keep taking anti-rejection drugs or
immunosuppressants - (suitable) donor may not be available or need for tissue
matching - risk from surgery (e.g. anaesthesia or infection)
- recovery from surgery will take a long time
- does not last forever (therefore further surgery needed)
Marathon runners often drink sports drinks during a race.
Explain why
to replace water / ions / salt
(that is) lost in sweat
Name the process by which water is lost from the skin.
sweat(ing)
Why does the body need to lose water from the skin?
any one from:
* for cooling
* to maintain body temperature
Which organ monitors body temperature?
brain
The organ that monitors internal body temperature receives
information about temperature from the skin.
Which structures in the skin send impulses with this information?
receptors
How does sweating help to control body temperature?
cools us down
Body temperature is kept within a narrow range.
When the core body temperature is too low, this is detected by the
thermoregulatory centre in the brain.
Describe how the body responds when a decrease in core body temperature is
detected.
blood vessels supplying skin
constrict
allow vasoconstriction
do not allow capillaries /veins constricting
do not allow moving blood vessel
less blood flow (to / through capillaries / to skin)
allow blood flows further away from skin surface
so less energy is lost (to the surroundings)
allow less heat is lost
‘shivering’ by muscle (contraction)
allow muscles contract (and relax) rapidly
releasing energy or respiring (more)
if the eye then focuses on the words in a book, changes would occur in the eye.
The light rays would be refracted more by the lens.
(b) How does the lens refract the light more
by becoming thicker
Which two structures control the shape of the lens?
ciliary muscles
suspensory ligaments
To form a clear image, the light rays entering the eye must focus on one
structure in the eye.
Name the structure.
retina
What is meant by the term ‘reflex action’?
response / reaction
automatic or no thinking or not conscious or involuntary
A woman’s hand accidentally touches a hot object.
The woman moves her hand away rapidly.
Describe how the woman’s nervous system coordinates the reflex action
receptor (in skin of finger / hand) detects stimulus / temperature
change
allow receptor detects heat ignore pain
(electrical) impulses pass along neurones
allow electrical signals pass
along nerve cells
ignore messages
(impulses pass from) sensory to relay to motor neurones
synapse between neurones where chemical crosses gap
allow neurotransmitter / acetylcholine
for chemical
allow by diffusion
(synapses) in spinal cord / CNS
ignore brain
muscle contraction (to pull hand away)
or effector is a muscle
Give three ways coordination by the endocrine system is different from
coordination by the nervous system.
coordination by endocrine system is:
slower
longer-lasting
(chemical / hormone) via blood instead of electrical / impulse /
neurones
Which part of the brain controls balance when riding a bicycle?
cerebellum
The ears send information about sound to the brain.
Which word describes the brain?
coordinator
What type of cell carries impulses from the ears to the brain?
neurone
Which part of the eye has cells that detect light?
retina
The eyes of some birds have specialised cells to detect ultraviolet (UV)
light.
Some fruits reflect UV light.
Explain why it is an advantage for birds to be able to detect UV light.
can see fruit / food
(so) get more food
What process occurs in the eye when the student looks at the trees instead of the book?
accommodation
What change happens in the student’s eyes when they look up at the trees?
light rays are refracted less
Name the common defect of the eye which causes distant objects to
appear out of focus.
- myopia
- short-sightedness
Name the part of the brain that is responsible for making a decision
(cells in) retina sensitive to light
impulse passes along (sensory) neurone
(along) optic nerve
Suggest how the fMRI scanner could help to find out more about the brain
damage a person has
- can ask people to do different tasks (while taking scan)
allow can ask person to do a (specific)
task - to see which part of brain is active / inactive
allow to see which part of the brain is
working - to compare with a person without brain damage
- to see (exactly) where the damage is
- (traditional) MRI scanner cannot be used if people can’t stay still
Describe how the brain receives information about light entering the eye.
(cells in) retina sensitive to light
impulse passes along (sensory) neurone
(along) optic nerve
Explain how birds that detect UV light have evolved from birds that could
not detect UV light
- mutation (in gene / DNA)
- randomly or due to chance
- causes new / different protein / (visual) pigment to be made
- in the retina of bird
- (so more) variation in the wavelengths of light birds retinas
could detect - birds with the mutation or birds able to detect UV are more
likely to see fruits (that reflect UV) - birds with the mutation or birds able to detect UV are more
likely to see where small mammals are or have been - therefore get more food (small mammals or fruit)
- avoid being eaten (by small mammals)
- out competing those birds without the mutation or birds not
able to detect UV - so more likely to survive and reproduce or have offspring
- by natural selection
- passing on allele / gene / mutation to offspring
- repeated over many generations
What is a reflex action?
- fast / rapid
- protect (from danger / harm)
- a response / a reaction
ignore ‘action’ - automatic / involuntary or not under conscious control
A muscle in the arm moves the hand away from the hot object.
How does the arm muscle do this?
the muscle contracts
‘Drinking coffee speeds up reactions.
Give evidence from the table above to support the students’ conclusion
(after drinking coffee) ruler falls less far (before being caught)
Explain how the person’s eye could adjust to form a clear image of a
nearer object.
ciliary muscles contract
(so ciliary muscles have a) smaller diameter
(so) suspensory ligaments loosen / slacken
do not accept ‘relax’
(so) lens thickens or lens becomes more curved / rounded
(thicker) lens is more convergent
light rays / image focused on retina
Explain why a long-sighted person has difficulty seeing near objects
clearly.
eye(-ball) is (too) short or lens cannot be thickened enough
(so) light ‘focuses’ behind retina
Long-sightedness can be corrected by wearing spectacles.
Describe how spectacle lenses can correct long-sightedness.
convex / converging lens
light rays bent / refracted (inwards) more
light rays focused on retina
Describe how the structures shown in Figure 2 help to coordinate a reflex
action.
- receptor detects stimulus
- e.g. receptor detects pressure
- receptor generates impulses / electrical signals
- neurones conduct impulses / electrical signals
- neurone A conducts impulses to spinal cord
- neurone A = sensory neurone
- synapse between neurones
- chemical (/ neurotransmitter) crosses synapse
- chemical stimulates impulse(s) in neurone B
- neurone B = relay neurone
- neurone C = motor neurone
- effector carries out response
- e.g. muscles of the arm / leg contract
- muscles contract or gland secretes chemicals
The students measured 10 reaction times for each person rather than 3
reaction times
to increase validity / repeatability
or
to get representative results
because of variation in results
Give one conclusion about the effect of caffeine on reflex actions.
caffeine speeds up reflex actions
or
reduces reaction time
Describe the changes in the pupil and iris going from A to B in Figure 1.
Explain how these changes occur.
Refer to the changes in light level in your answer
pupils dilated (at B)
in dim light / low light levels
because circular muscles (in iris) relax
(and) radial muscles contract
Explain how the blurred vision is corrected.
figure 2 shows myopia where light does not focus on the retina
in figure 3 the lens bends the light so that light focuses on the retina
A woman has a head injury.
Her symptoms include:
* finding it difficult to name familiar objects
* not being able to remember recent events.
Suggest which part of her brain has been damaged.
cerebral cortex
A man has a head injury.
He staggers and sways as he walks.
Suggest which part of his brain has been damaged.
cerebellum
Why is it more dangerous for old people to drive cars?
reaction time (too) long or reactions (too) slow
(so) more likely to have / cause an acciden
Describe the difference between the function of a receptor and the function
of an effector
receptors detect / sense stimuli / change in surroundings or convert
stimulus into an impulse
example of a receptor
allow any appropriate organ or part of an organ, eg
eye / retina or named type of receptor eg light
effectors allow / make response or convert an impulse to an action
(effector) muscle / gland
What is a synapse?
junction
between neuron(e)s
Describe how information passes across a synapse.
chemical released
- (chemical released) from one neurone
ignore produced - (chemical) passes (across synapse) to next neurone to
stimulate / cause (electrical) impulse
allow diffuses for passes (across)
Name a sense organ involved in a reflex co-ordinated by the spinal
cord.
skin
In reflexes co-ordinated by the brain there are no relay neurones.
Suggest why there is a difference in the mean speed of the impulse
for the two reflexes.
- synapses slow down transmission / impulse
allow idea of movement of chemical being slower
than electrical impulse - fewer synapses (via brain)
allow one synapse compared to two or only one
synapse - (therefore) fewer delays
