Author: Philip Colls
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Receptors – taxis and reflexes booklet revision questions   NAME:
Q1. Scientists investigated the effect of humidity on the movement of the insect, Tenebrio molitor.
The insects were placed in choice chambers with one side kept at 100% humidity and the other side kept at 30% humidity.
The insects were used one at a time and the path the insect followed recorded on paper.
Figure 1 shows a typical result. The solid dot shows the final recorded position of the insect.
Figure 1
 
(a)     What type of behaviour was shown by the insect in Figure 1?
Give evidence from Figure 1 to support your answer.
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(b)     The scientists found that the insects moved for 94% of the time in the more humid side, but in the drier side they moved only 20% of the time. The scientists concluded that reduced movement in the drier side was an adaptation that reduced water loss.
Use your knowledge of gas exchange in insects to explain how this behaviour would reduce water loss in the insects.
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(c)     Tenebrio molitor has two antennae on its head. These are sense organs.
The scientists found that one insect stopped when it reached the boundary between the two sides of the choice chamber and seemed to perform various movements with its antennae. The insect then moved to the drier side.
This behaviour can be seen in Figure 2. The points marked with a Q indicate where the insect showed this behaviour.
Figure 2
 
What type of behaviour did the scientists conclude that the insect in Figure 2 was showing?
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(1)
(d)     After observing the behaviour of the insect in Figure 2, the scientists hypothesised that if an insect had one of its antennae removed it would have a tendency to turn to one side and move in circles. The scientists tested this hypothesis by cutting one antenna off another insect and observing its movement.
The result of this experiment can be seen in Figure 3.
Figure 3

Does the movement observed in Figure 3 support the scientists’ hypothesis?
Give the reason for your answer.
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(e)     The scientists then investigated the effect of a range of humidities on the activity of the insects. Figure 4 shows their results. The triangles represent the number of insects still moving after 15 minutes.
Figure 4
 
A student studying Figure 4 concluded that as humidity increases, so does movement of the insects.
Evaluate the student’s conclusion.
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 (2)  (Total 9 marks)
Q2. Termites are insects. Some species live in colonies in the soil. Although most termites are wingless, winged termites are sometimes produced. The winged termites fly from the soil, mate and start new colonies.
A scientist studied the behaviour of winged termites. He divided these termites into three groups.
•        Group A had their eyes covered.
•        Group B had their antennae removed.
•        Group C was the control group.
He put individual winged termites on a sloping board that was illuminated from one side. The diagram shows the direction of movement of a typical termite from each of the three groups.
 
(a)     (i)      What type of behaviour was shown by the termite from group B?
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(ii)     Give the evidence for your answer.
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(b)     Explain what the results from group A suggest about the factors controlling the behaviour of winged termites.
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(3)
(c)     Suggest one advantage to the termites from group C of the behaviour shown in the investigation.
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(2)
(Total 7 marks)
Q3.
Woodlice use gills for gas exchange. These gills are situated on the outside of the animal so water loss occurs from the gill surface. When a number of woodlice occur together they often form a ‘clump’ with individual woodlice touching each other.
A student investigated the effect of clumping on the rate of water loss from the woodlice. The student divided the 12 woodlice into two groups. He allowed the woodlice in group A to clump together, but kept the woodlice in group B separate from each other.
The following table shows the mean mass of the woodlice in each group.
 
Time / minutes | Mean mass of woodlice / g
| Group A | Group B
0 | 0.180 | 0.175
20 | 0.170 | 0.130
40 | 0.165 | 0.110
60 | 0.160 | 0.090
80 | 0.160 | 0.080
(a)     (i)      Calculate the percentage loss in the mean mass of the woodlice in Group A during the investigation. Show your working.

 
 
Answer ____________________
(2)

(ii)     Woodlice in Group B had a greater percentage loss in mean mass during the investigation than woodlice in Group A. Explain why.
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(iii)    It would be useful to give the loss in mean mass as a percentage in this investigation.
Explain why.
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(Total 6 marks)
Q4.
The diagram below shows a nerve pathway in an animal.
 
(a)     The nerve pathway shown in the diagram may be regarded as a simple reflex arc.
Use the diagram to explain why.
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(b)     Suggest two advantages of simple reflexes.
1. _________________________________________________________________
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2. _________________________________________________________________
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(2)
(c)     In the nerve pathway in the diagram, synapses ensure that nerve impulses only travel towards the muscle fibre.
Explain how.
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(2)
(d)     Axon P was found to conduct impulses much faster than other axons in the nerve pathway shown in the diagram.
Describe and explain one feature of axon P that might cause this difference.
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(2)
(Total 7 marks)

Q5. A biologist investigated the behaviour of a species of worm that lives in soil. He cultured three samples of worms in three separate trays of soil for many days. Each culture:
•        contained a food supply
•        was kept at a different temperature.
The temperatures of the cultures were 17 °C, 20 °C and 23 °C. The biologist then removed food from the trays for several hours. Then he transferred each sample of worms onto a glass surface where there was no food. Each surface had a temperature gradient across it. After 1 hour, the biologist recorded the position of each worm.
The figure below shows his results. On each diagram,  marks where he released the worms onto the glass surface.
Temperature gradient
                        
Temperature gradient
     
Temperature gradient
                         
(a)     The biologist concluded that the worms’ behaviour demonstrated taxis.
How do these results support this conclusion?
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(b)     Using the information provided, suggest an explanation for the worms’ behaviour on the glass surfaces in the absence of food.
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(c)     In each experiment, the biologist exposed the surfaces to light that was dim and even, so he could see where the worms went.
Apart from seeing where the worms went, suggest two reasons why it was important that the light was dim and even.
1. _________________________________________________________________
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2. _________________________________________________________________
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(Total 7 marks)
Q6.
When a finger accidentally touches a hot object, a reflex action occurs. The biceps muscle contracts, causing the arm to be flexed and the finger is pulled away. The diagram shows the arrangement of the bones in the arm, the muscles used for flexing and straightening the arm and the nervous pathways associated with the contraction of these muscles.
 
(a)     Explain the importance of reflex actions.
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(3)
(b)     (i)      Describe the sequence of events which allows information to pass from one neurone to the next neurone across a cholinergic synapse.
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(6)
(ii)     Give two differences between a cholinergic synapse and a neuromuscular junction.
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2. ____________________________________________________________
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(2)
(Total 11 marks)
Q7.
A student investigated the effect of distance from a forced turn on the direction woodlice turned when next given a choice. The following figure shows her results.
 
(a)     Describe the response of woodlice to increased distance between turns.
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(b)     Can you conclude that woodlice show turn alternation behaviour when the distance between the forced turn and the second turn was 10 cm?
Explain your answer.
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(2)

(c)     The student suggested that the difference in turning behaviour of the woodlice in her investigation was due to the distance between the first and second turn. Her friend suggested that it was due to the time taken to get from the first to the second turn and not the distance. Suggest how you could investigate which of these two possibilities is more likely.
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(3)
(d)     Woodlice usually live in areas where stones and twigs form obstacles. Obstacles in the path of woodlice cause them to make forced turns. The more obstacles there are in the path, the shorter the distance between the forced turns.
Use the data in the figure above to explain how the behaviour of woodlice results in them moving rapidly out of unfavourable areas.
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(2)
(Total 9 marks)

Mark schemes
Q1.
(a)     1.      Kinesis;
Ignore any prefix
2.      Movement is random / non-directional
OR
Insect is not moving towards a particular stimulus;
2
(b)     1.      Less respiration so less gas exchange;
2.      (So) spiracles open less so less water loss;
2
(c)     Taxis;
Ignore any prefix
1
(d)     No (no mark), the insect does not move in circles;
Shows kinesis / results similar to Figure 1;
2
(e)     For (max 1)
1.      The data show a positive correlation;
Must state this as the description is given in the stem.
2.      Large sample / number of insects so valid / reliable / representative;
Against (max 1)
3.      (however) there are overlaps in individual experiments at all humidities;
4.      70–90% humidity there is little / no change in movement / movement only increases after 76% humidity;
Accept any value in this range
2 max
[9]
Q2.
(a)     (i)      Taxis;
Ignore references to positive and negative, and prefixes such as photo-
Accept taxes / tactic
Allow phonetic spelling
1
(ii)     Moves towards stimulus / towards light;
Direction must be correct.
1
(b)     Gravity;
Antennae involved;
Doesn’t show light is involved / doesn’t respond to light as they are
unable to see / as eyes are covered;
Accept geotaxis
3
(c)     Helps them to leave the soil / ground / reach the surface;
Disperse / produce new colonies;
Avoid competition;
2 max
[7]
Q3.
(a)     11.1;;
Allow one mark for calculating loss in mass as 0.02g and calculating a percentage;
Accept 11.11 / 11 but not 11.0
2
(b)     1.      (More mass loss) linked to losing more water;
2.      Gills (more) exposed to air / covered (less) by other woodlice so greater surface area (exposed);
3.      (Not clumped) so lower humidity (around each woodlouse) so greater evaporation / diffusion (of water);
Assume ‘They’ refers to woodlice in group B
3
(c)     Initial masses different;
1
[6]
Q4.
(a)     Only 3 neurones / nerve cells (in reflex arc)
1
(b)     1.      Rapid;
2.      Protect against damage to body tissues;
3.      Do not have to be learnt;
4.      Help escape from predators;
5.      Enable homeostatic control.
2 max
(c)     1.      Neurotransmitter only made in / stored in / released from pre-synaptic neurone;
2.      (Neuro)receptors only on the post-synaptic membrane;
2
(d)     1.      Axon P is myelinated;
2.      So shows saltatory conduction / impulses jump between nodes of Ranvier
OR
3.      Axon P has a larger diameter;
4.      So less resistance to flow of ions.
Mark as 1 & 2 OR 3 & 4
2
[7]
Q5.
(a)     1.      (Taxis is) movement towards / away from a stimulus / a directional response / movement (to a stimulus);
2.      (Move towards) temperature they were used to / cultured in;
Movement towards temperature they were used to = 2 marks
2 max
(b)     1.      Hungry, so seeking food / in absence of food respond to temperature;
Ignore references to temperature and enzymes
Must be stated not inferred from other statements
2.      Move towards temperature they were used to / cultured in;
3.      Associate (this temperature) with food;
Accept they think food is here
Stated not inferred
4.      (Then) stay in this temperature;
3 max
(c)     1.      (Dim) worms live in soil / dark / affected by bright light / dim light is like normal environment / what they are used to;
2.      (Even) because worms might move towards / away from bright light / to avoid creating light gradient / prevent worms showing phototaxis / all parts of surface exposed to same light;
Accept to avoid kinesis due to light
3.      (Dim light) ensures heat from light not a variable / heat from lamp could kill / dry out worms;
Not just to control variables / factors
2 max
[7]
Q6.
(a)     1. automatic (adjustments to changes in environment) / involuntary;
2. reducing / avoiding damage to tissues / prevents injury / named injury
    e.g. burning;
3. role in homeostasis / example;
4. posture / balance;
5. finding / obtaining food / mate / suitable conditions;
6. escape from predators;
(ignore ‘danger’ or ‘harm’ unless qualified)
3 max
(b)     (i)      1. (impulse causes) calcium ions / Ca^++ to enter axon;
2. vesicles move to / fuse with (presynaptic) membrane;
3. acetylcholine (released);
4. (acetylcholine) diffuses across synaptic cleft / synapse;
5. binds with receptors on (postsynaptic) membrane; 
(reject active sites, disqualify point)
6. sodium ions / Na^+ enter (postsynaptic) neurone;
7. depolarisation of (postsynaptic) membrane;
8. if above threshold nerve impulse / action potential produced
6 max
(ii)     neurone to neurone and neurone to muscle;
action potential in neurone and no action potential in muscle / 
sarcolemma;
no summation in muscle;
muscle response always excitatory (never inhibitory);
some neuromuscular junctions have different neurotransmitters;
(penalise ‘nerve’ once)
2 max
[11]
Q7.
(a)     Decrease (woodlice turning in opposite direction to forced turn with increasing distance between turns) then more rapid decrease;
(Rapid decrease) when distance between turns is 9cm / 80% woodlice turning in opposite direction;
Accept ‘after 9cm’ or between 9 and 10cm’ but not at 10cm
2
(b)     No (no mark)
Equal numbers / 50% turn each way;
(Would expect this) by chance / at random;
2
(c)     1.      Keep distance same;
2.      Increase time / delay woodlice / decrease speed of woodlice
3.      (Increase time) between forced and second turns;
Allow one mark for measure time taken for stated / set distance
3
(d)     Short distances result in more (woodlice showing) turn alternation;
Keeps woodlice going in one direction / stops them going round in circles;
2
[9]