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(a) Fig. 1.1 shows seven species of fish that live on reefs in the Caribbean.
Use the key to identify each species. Write the letter of each species (A to G) in the correct box beside the key. One has been done for you.
Key
| 1 (a) | Body shape is long and narrow, at least 10 times as long as its depth | go to 2 |
| Body shape is not long and narrow, less than 10 times long as its depth | go to 3 | |
| 2 (a) | Fins are pointed | Aulostomus maculatus F |
| Fins are smooth | Gymnothorax moringa | |
| 3 (a) | Both eyes are on top of the head | go to 4 |
| Eyes are on either side of the head | go to 5 | |
| 4 (a) | Tail fin is long and thin | Dasyatis americana |
| Tail fin is short | Bothus ocellatus | |
| 5 (a) | Fish has one or several dark spots | go to 6 |
| Fish has no dark spots | Epinephelus striatus | |
| 6 (a) | Fish has two fins on its back | Pseudupeneus maculatus |
| Fish has more than two fins on its back | Chaetodon capistratus |
The wavelengths of light that penetrate water influence the features of fish. Blue light does not penetrate far into water; red light penetrates much further.
Many different species of cichlid fish live in Lake Victoria in Africa. Some species live in shallow water and others live in deeper water.
Table 1.2 summarises some of the features of males and females of these species.
Table 1.2
| habitat | body colour of males | retina in eyes of females |
| shallow water | blue | detects blue light |
| deep water | red | detects red light |
Body colour and colour vision are both inherited features. Females select the males that they mate with and prefer bright coloured males. Male and female eyes of the same species of cichlid fish are similar.
(b) (i) The ancestors of red and blue cichlid fish were brown.
State how the different body colours of the males first happened.
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(ii) Suggest the advantages of different cichlid fish being able to detect blue and red light.
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(c) Lake Victoria receives considerable pollution from the surrounding area which makes the water cloudier and reduces the penetration of blue light.
Suggest and explain the likely long-term effects of the cloudy water on the red and blue cichlid fish.
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540
566
554
Fig. 2.1 shows a diagram of human skin in hot weather.
(a) Name structures A to D.
A ............................................................................................................................
B ............................................................................................................................
C ............................................................................................................................
D ............................................................................................................................ [4]
(b) Describe how the structures (A to D) in the skin help to maintain a constant body temperature. You may refer to the structures by their letters.
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(c) (i) Blood flow through the skin changes in response to changes in the air temperature. State and explain what happens to blood flow through the skin when the temperature of the surrounding air becomes very cold.
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(ii) Explain how the changes you have described in (c)(i) reduce heat loss.
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(d) The control of body temperature is an example of negative feedback. Describe how negative feedback is involved in the control of body temperature.
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588
569
586
(a) Describe how sucrase catalyses the breakdown of sucrose. You should refer to Fig. 3.1 in your answer.
[Image_Fig_3.1]
[3]
(b) Three enzymes, \textbf{P}, \textbf{Q} and \textbf{R}, were extracted from different regions of the alimentary canal of a mammal. The effect of pH on the activity of the enzymes was investigated at 40 \textdegree C. The results are shown in Fig. 3.2.
[Image_Fig_3.2]
(i) Explain why the investigation was carried out at 40 \textdegree C.
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[2]
(ii) Using information in Fig. 3.2, describe the effects of increasing pH on the rate of activity of enzyme \textbf{Q}.
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[3]
(iii) Enzymes increase the rate of breakdown of different types of food substances in digestion.
Name enzymes \textbf{P}, \textbf{Q} and \textbf{R}.
P ..................................................................................................................................................................
Q ..................................................................................................................................................................
R ..................................................................................................................................................................
[3]
(c) Some baby foods are manufactured by pre-digesting foodstuffs containing carbohydrates, fats and proteins with enzymes.
Describe the roles of different types of enzymes in preparing these baby foods.
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[4]
536
549
556
(a) Compare the growth curve shown in Fig. 4.1 with a sigmoid growth curve.
(b) (i) Calculate the percentage loss of forest in Brazil between 1990 and 2005. Show your working.
Answer: ..................................................%
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(ii) State two reasons why forests are cut down.
1. ................................................................................
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2. ................................................................................
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[Table_1]
(c) Outline the effects of large scale deforestation on the following aspects of the environment.
number of species ..................................................................................
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soils ....................................................................
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rivers ....................................................................
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atmosphere ............................................................
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[8]
(d) Drinks cartons have proved difficult to recycle because they are made of plastic, aluminium and paper. A factory in Brazil uses new technology to recycle all these components as raw materials for the packaging industry.
Explain the importance for the environment of developing technologies for recycling materials, such as those found in drinks cartons.
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[3]
531
588
548
Fig. 5.1 shows a root hair cell.
(a) Name structures A, B and C.
A
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B
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C
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(b) Explain two ways in which root hair cells are adapted to carry out their functions.
1.
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2.
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(c) Root hair cells need a supply of sugars to provide energy.
Explain how root hair cells obtain a supply of sugars.
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[2]
517
548
542
Fig. 6.1 shows the changes in the concentrations of four hormones during one menstrual cycle.
(a) State what happens at X and at Y during the menstrual cycle.
X ..........................................................................................................................
Y .......................................................................................................................... [2]
(b) Describe the roles of oestrogen in controlling the menstrual cycle.
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(c) Some women who cannot conceive may be treated with FSH.
(i) Describe how FSH is used as a fertility drug and how it may allow a woman to conceive.
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(ii) Suggest one implication of using fertility drugs.
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(d) Explain why it is important that FSH is not secreted during pregnancy.
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550
535
552
