ppq Flashcards
. FURA-2 is a fluorescent dye that can be used to measure the concentration of Ca2+ ions inside cells.
Scientists have used FURA-2 to study the role of Ca2+ ions in the synapses of living nerve tissue.
FURA-2 was injected into a single sensory neurone that was connected by a synapse to a relay neurone.
FURA-2 fluorescence inside the neurone was observed using a confocal microscope.
i. Explain one advantage of using a confocal microscope in this study
it can be used with living cells
The sensory neurone was stimulated electrically and the FURA-2 fluorescence in the synaptic bulb
was measured. At the same time, an electrode recorded the membrane potential in a postsynaptic
neurone.
The results of this study are shown in the table.
Strength of electrical
stimulation
Low
medium
high
FURA-2 fluorescence in
synaptic bulb
Low
medium
high
Highest membrane potential
in postsynaptic neurone (mV)
-60
+40
+40
The intensity of FURA-2 fluorescence is proportional to the concentration of Ca2+ ions.
The scientists concluded that changes in the concentration of Ca2+ ions in the presynaptic neurone caused
an action potential in the postsynaptic neurone.
Evaluate and explain the scientists’ conclusion.
vaild:
.conc of Ca2+ is proportional to strenght of stimulus
.Ca2+ change from low,medium,high causes a increase in potential
not vaild:
.changes in Ca2+ conc may be caused by action potential
.Ca2+ change from medium to high but no change in potential
Many insects such as moths and bumblebees are insulated with scales and hair, and are known as
facultative endotherms.
Their metabolism during flight can cause the temperature of the flight muscles to increase 20–30 °C
above the external temperature.
i. Using the information provided, explain why many moths and bumblebees are described as
endothermic.
.generate heat via respiration
It is more difficult for moths and bumblebees to maintain their body temperature than for mammals and
birds to maintain their body temperature.
Explain why
insects have a larger SA:VOL ratio and so loose heat faster
The naked mole rat is a mammal. However, it has several features that are unusual for mammals.
Naked mole rats regulate their temperature in a way that is different from most mammals.
i. Some features of thermoregulation in naked mole rats are listed below:
*
They live in complex underground tunnel systems, which tend to have a stable temperature
of 30–32 °C. However, sometimes the environmental temperature can increase or decrease
outside this range.
* In experiments that examine environmental temperature changes, the core body temperature
of naked mole rats remains close to that of the environmental temperature.
* When tunnel temperature increases they often move to cooler parts of the tunnel system.
* When tunnel temperature decreases they often lie together in large groups.
Outline two ways in which thermoregulation in naked mole rats is different from thermoregulation in most
mammals
.mole rats have a lower body temp
.no fur for insulation
In humans, when core body temperature falls below 35 °C, positive feedback causes this decrease in
core body temperature to continue. This process is known as hypothermia.
Explain how positive feedback could accelerate the process of hypothermia.
.positive feedback is when an initial change is increased further
.lower temp reduces kinetic energy so enzyme activity is slowed
.respiration rate falls
are these statements true or false
Peripheral temperature receptors detect the temperature of internal
organs
Receptors in the hypothalamus detect core body temperature
Blood temperature is detected by the receptors in the hypothalamus
Temperature receptors send impulses to the medulla oblongata, which
regulates body temperature
F
T
T
F
Temperature receptors send impulses to the medulla oblongata, which
regulates body temperature
hypothalamus
Name the type of sensory cell in the skin that detects changes in environmental
temperature.
peripheral temperature receptor
Name the corrective homeostatic mechanism that works to restore any changes in body
temperature to the normal range.
negative feedback
the responses that conserve heat
.contraction of erector pili muscles( attached to hairs)
.curling up
.vasoconstriction of arterioles
the responses that cool the body.
sweating
finding shade
a physiological response that generates heat.
shivering
a behavioural (not physiological) response to a decrease in environmental temperature.
curling up
Explain how each of the following adaptations help the animal to control its body temperature.
Elephants have large, thin ears that they move backwards and forwards when hot
Penguins living in cold climates have ‘shunt’ blood vessels. These shunt vessels link
arterioles carrying blood towards their feet with small veins that carry blood away from
their feet.
.large SA and increases air movement over skin
.less blood flow to feet
Explain what is meant by the term homeostasis.
.maintaining a stable internal enviroment within set limits
Describe how negative feedback is used to control blood glucose concentration.
.beta cells detect change
.
if high:
.beta cells release insulin
.absorption of glucose by liver cells
.glucose enters via transport proteins
.glucose converted into glycogen
if low:
.alpha cells release glucagon
.conversion of glycogen into glucose
.conversion of amino acids and lipids to glucose
With reference to Fig. 1.1, describe and explain the role of ATP in the cell.
.releases energy by removing phosphates via hydrolysis
.energy released for metabolism
.ADP attach to a phosphate during respiration and photosynthesis
Describe the way in which an endothermic animal, such as a mammal, normally prevents
its body temperature from decreasing when the external temperature decreases.
.thermoreceptors are stimulated and sends an impluse to the hypothalamus
.vasocontriction of arterioles near skin to reduce heat loss via convection
.increased respiration to generate heat
Describe the components and events involved in a reflex arc and benefit
.action potential in sensory neurone
.to relay neurone
.to motor neurone
.increased movement of AP
A statocyst sensory receptor is shown in Fig. 2.1.
What can you conclude from Fig. 2.1 about the mechanism by which a statocyst acts as a transducer?
.kinetic energy is converted into electrical energy
.statolith moves sensory hairs
se the information in Fig. 2.2 to suggest why naked mole rats do not feel pain when exposed to acid.
.no AP impluses along neurons to CNS
.due to no voltage gated channels open
. Multiple sclerosis ( is an autoimmune disease that damages the nervous system.
i. Suggest how the immune system causes damage to the nervous system.
.antigens on neurones activate immune system
.phagocytes break down neurones
One of the neurones has been affected by MS
MS causes changes to neurones, which reduce the speed at which nervous impulses are conducted.
Using information from Fig. 5, what can you conclude about how MS causes a reduction in the speed of
nervous impulses?
.fewer schwann cells
.no saltatory conduction
Why is transmission of action potentials along the axon slower in the absence of saltatory conduction?
no nodes of Ranvier
*The amplitude and duration of the action potentials in a single neurone are always the same. However,
the amplitude and duration of action potentials can vary between different types of neurone.
Fig. 2.3 shows action potentials in two different types of neurone.
Fig. 2.3
Describe the differences between the two action potentials and suggest explanations for the differences
you have described
.dopamine is less polarised, AP peak is lower and AP duration is longer
.could be beacause that the restining potential is set up by diff type of sodium/potassium pumps in neuron, diff type of potassium ion channels and diff sodium/potassium ion channels in purkyne neurone
The greater blue-ringed octopus, Hapalochlaena lunulata, is one of the most venomous of all animals.
Its bite contains tetrodotoxin (TTX), a neurotoxin that can cause paralysis and death within minutes.
i. The following information has been discovered about the effects of TTX on nerve cells:
- TTX binds to the external surface of the voltage-gated sodium ion channels in the axon
membrane. - Binding of TTX changes the tertiary structure of the channel.
- This means the channel cannot open.
Using the information provided, explain how TTX affects the activity of neurones.
.sodium ion cannot enter
.mo depolarisation of membrane
.membrane remains at resting potential
.prevents action potential being generated
