q1. · web viewthis question gave details of the reflex arc involved with pupil reflex. in part (a)...
TRANSCRIPT
2J Coordination
Time: 1 hour 5 minutes
Total marks available: 65
Total marks achieved:
Q1.
(a) Complete the table to show the characteristic features of the three groups of organisms.Use a tick if the group has the characteristic and a cross if the group does not have the characteristic. The first box has been done for you. (4)
(b) The table below shows some characteristics shared by most animals. Complete the table by giving the missing characteristics and examples. (4)
(c) Another characteristic shown by animals is the ability to respond to their surroundings.
For example, a person may withdraw their hand from a hot object. Describe the sequence of events that cause this response.
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(5)
(Total for question = 13 marks)
Q2.
The diagram shows a section through the human eye.
(a) Name the structures labelled A, B and C.
A ...............................................................................................B ...............................................................................................C ...............................................................................................
(b) Explain the changes that take place in structures B and C when a person focuses on a nearby object.
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(c) Structures in the eye respond to stimuli by means of reflex actions.(i) Describe one reflex action that occurs in the eye.
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(ii) Give a reason for this reflex action.
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(iii) Human responses are also controlled by hormones.
(3)
(2)
(2)
(1)
For one named example of a hormone, give its site of production and its effect.
Hormone
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Site of production
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Effect
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(3)
(Total for question = 11 marks)
Q3.
Students carried out a simple investigation to show how the sensitivity of the skin differs on the finger tips, the back of the hand and the wrist.
Students worked in pairs.The two prongs of a hairpin were fixed 0.5 cm apart.This hairpin was then used by one student to touch the skin of another student, who was looking away.The first student used both prongs or one prong as a stimulus.The second student then indicated whether he thought both prongs or just prong was used.His response was recorded as correct or incorrect .This was repeated 10 times for each area of the skin.The procedure was then repeated using prongs 1 cm apart and 2 cm apart. Students could then identify the most sensitive area of the skin.
(a) Some of the percentages of correct responses at each distance have been recorded in the table. Complete the table by writing in the missing percentages.
(2)
(b) On the grid provided, plot a bar graph to show how sensitivity changes with each
area of the skin.
(c) Which area of the skin is the most sensitive? Explain your answer.
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(d) Suggest a reason for the difference in sensitivity between the areas of the skin.
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(e) The teacher told the students to touch the skin with the prongs using the same pressure each time. Suggest a reason for this.
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(1)
(Total for question = 13 marks)
Q4.
The diagram shows the difference in the pupil diameter of the eye in bright light and after moving into dim light. The difference is caused by a reflex action.
(a) The table gives descriptions of parts of the reflex arc involved with the reflex action.
Complete the table by naming each part.
One has been done for you.(3)
(b) Explain how the lens changes when you view a near object.
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(4)
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(Total for question = 7 marks)
Q5.
Antiperspirants are used to reduce sweating under the arms.
An investigation was carried out to find out the effectiveness of an antiperspirant. Ten students put antiperspirant on the skin of their left armpit. No antiperspirant was put on the skin of their right armpit. Each student then weighed two pieces of cotton wool and placed one piece under each armpit. The cotton wool was used to absorb any sweat that was produced.
The ten students exercised at the same intensity for five minutes and then reweighed each piece of cotton wool.They calculated the percentage increase in the mass of the cotton wool. Their results are shown in the table.
(a) The results for the left armpits with antiperspirant contain one anomalous result.Calculate the correct average for the percentage increase in mass of the cotton wool with antiperspirant. Show your working.
(2)
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(b) The results for the right armpits without antiperspirant are not all the same. Suggest two reasons to explain this.
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(c) Which of the following formulae, A, B, C or D, should be used to calculate the percentage increase in the mass of each piece of cotton wool.
Put a cross in the correct box.
(d) Exercise increases the rate of sweating, but people also sweat at rest.(i) Explain how the rate of sweating of a person at rest is affected if that person is in hot air.
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(ii) Explain how the rate of sweating of a person at rest is affected if that person is in air with a high humidity.
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(2)
(Total for question = 9 marks)
Q6.
One of the characteristics of living organisms is the ability to respond to a change in their surroundings.
In mammals, such as humans, responses are controlled by nervous or hormonal communication.
(a) ADH is an example of a hormone.(i) Where is ADH produced?
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(ii) Describe the effects of ADH in the body.
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(b) Describe two ways in which nervous communication differs from hormonal communication.
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(c) Plants are also able to respond to their surroundings. The diagram shows young cereal shoots (coleoptiles) which are placed in different light conditions.
Complete the diagram to suggest how each of the shoots would appear after two days.(3)
(d) Plant roots also respond to external stimuli.Describe the response of roots to gravity and explain how this response benefits the plant.
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(3)
(Total for question = 12 marks)
Q1.
Part (b) asked candidates to complete a table to show the features of bacteria fungi and viruses. Most scored well on this item and on (b) which required linking characteristics of life with examples. In part (c) candidates had the opportunity to describe the events in the withdrawal reflex. Most who had learnt the components scored well.
Q2.
This question examined student understanding of the eye. The conjunctiva was correctly recalled by only the best candidates, with most responses naming part A as the cornea. Part B, the lens, was easily recognised by most but, part C, the ciliary muscle, was often wrongly recognised as the suspensory ligaments. The examiners were looking for references to the ciliary muscles contracting and the lens shape changing to be more convex in order for credit to be given in part
(b). Many candidates gained full marks, though their choice of terminology was often lacking in precision. Part (c) (i) and (ii) were done well with the most popular description being the pupil reflex in bright light. It was pleasing to note that the candidates were very knowledgeable about the hormones listed in the specification and, as such, part (iii) was well answered. However, there were some who were confused about the respective roles of progesterone and oestrogen when referring to the uterus wall, and about FSH and LH with regard to the timing of ovulation.
Q3.
This question described an investigation and presented data from a simple experiment to show how the sensitivity of the skin differs on the finger tips, back of hand and wrist. A similar experiment is described in the teachers' guide and in many textbooks. In part a) candidates had to compute the percentage correct from the raw data and almost all did this correctly. They then had to plot a bar graph in part b) to show the results of the investigation. Most did this very well and gained full marks. Some chose to combine data for the different distances and others chose to plot a line graph. In part c) most could use the data to identify that the finger tips are the most sensitive and then go on in part d) to suggest why. Many candidates suggested that on the finger tips one would find more receptors or that the nerve endings are closer together. In part e) most could suggest that if one varied the pressure then the experiment would not be a fair test and the better candidates explained why this would be the case.
Q4.
This question gave details of the reflex arc involved with pupil reflex. In part (a) students had to match parts of the reflex arc to the correct description. Most students were able to name the retina and the synapse but less identified the sensory neurone and the iris. In part (b) most students scored 3 or 4 marks for describing how the lens changes when viewing a near object.
Q5.
This question tested candidates on their understanding of a novel investigation and explored understanding of data analysis. The correct average in (a) should have been calculated by adding up all the values except any anomalous result and dividing by the number of these values. The result for student 9 was anomalous, so the total of 16 should have been divided by 9, not 10. The best candidates were aware of this. Wrong answers could still gain one mark if the examiners saw the number 16 in the working, showing correct addition of the values. Most gave at least one acceptable response in (b). Candidates who simply stated that sweat production differs in different people were notcredited unless they gave a valid explanation. Part (c) revealed that weaker candidates are unaware of the correct way to calculate a percentage increase. In (d) (i), most candidates appreciated that sweat production increases in hot
air in an attempt to cool the body. Part (d) (ii) was more challenging with only the best candidates appreciating that there is less evaporation in humid air, which leads to less heat loss and the response to sweat more in an attempt to cool the body. There was much confusion between the terms sweating and evaporation.
Q6.
In this question candidates needed to recall where ADH is produced. Most candidates stated the pituitary glands and some the hypothalamus. On this occasion at International GCSE we were prepared to accept the site of release and the site of production. In part (a) (ii) candidates had to describe theeffects of ADH on the body. The best responses described how ADH increases the permeability of the collecting duct wall. This leads to more water being reabsorbed into the blood by osmosis resulting in a smaller volume of more concentrated urine being released. Some candidates tried to describe the effect of less ADH and generally confused themselves.In part (b) most could recall two differences between nervous and hormonal communication. In part (c) candidates had to predict the outcome of an experiment on coleoptiles and light. Almost all could draw the correct response for the light from all around and most for unidirectional light few gained the mark for coleoptile in darkness. In (d) most candidates could describe the response of roots as positively geotropic and helping the plant by absorbing water and mineral ions. Fewer mentioned the role of the roots in anchoring the plant.
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