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(a) (i) The main component of milk is a liquid that is an important solvent in the body. State the name of this solvent. [1]
(ii) Table 1.1 shows some of the nutrients found in human milk, the elements that make up the nutrients, the enzymes that digest them and the products of digestion.
Complete Table 1.1.
(b) Milk also contains vitamins and mineral salts.
(i) Explain why vitamin D is important for the nutrition of children. [3]
(ii) Explain why iron is important in the diet. [2]
(c) Rubella and kwashiorkor are two diseases that affect children. Rubella is a transmissible disease and kwashiorkor is a non-transmissible disease.
(i) Define the term transmissible disease. [2]
(ii) Explain why women should be vaccinated against rubella before they reach reproductive age. [4]
(iii) Outline the causes of kwashiorkor. [2]
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(a) (i) State the name of molecule A in Fig. 2.1.
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(ii) State the name of structure B in Fig. 2.1.
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(iii) Explain the role of molecule A in protein synthesis, as shown in Fig. 2.1.
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(b) Insulin is secreted from cells in the pancreas when the concentration of glucose in the blood increases. Outline the role of insulin.
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(c) State the names of two substances, other than insulin, that are secreted by the pancreas.
1 ..................................................................................................................................
2 .................................................................................................................................. [2]
[Total: 11]
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532
Scientists measured the rate of photosynthesis in the leaves of a sunflower plant, *Helianthus annuus*. The scientists used the apparatus shown in Fig. 3.1 to measure the rate of photosynthesis.
(a) The apparatus in Fig. 3.1 maintains a constant temperature and a constant humidity.
(i) Explain why temperature has an effect on the rate of photosynthesis. [4]
(ii) Explain why the rate of photosynthesis will decrease if the humidity in the apparatus becomes very low. [3]
(iii) The apparatus was left for 15 minutes. Explain how the scientists would use the readings for the concentration of carbon dioxide in chambers 1 and 3 to calculate the rate of photosynthesis. [2]
(b) The scientists carried out another investigation using the same apparatus at different temperatures. They measured the rate of uptake of carbon dioxide in the light and then they measured the rate of release of carbon dioxide in the dark. The results are shown in Fig. 3.2.
(i) Use the information in Fig. 3.2 to complete Table 3.1.
[Table_1]
| temperature / °C | rate of uptake of carbon dioxide in the light / μg per hour per cm2 of leaf | rate of release of carbon dioxide in the dark / μg per hour per cm2 of leaf |
|---|---|---|
| 20 | ||
| 35 | 90 | 45 |
(ii) The scientists determined that photosynthesis in the leaves at 35°C used carbon dioxide at a rate of 135μg per hour per cm2 of leaf. Fig. 3.2 shows that the rate of carbon dioxide uptake at 35°C was 90μg per hour per cm2 of leaf. Explain why the rate at which carbon dioxide is used in photosynthesis is greater than the rate of carbon dioxide uptake. [2]
(iii) Explain why the results in Table 3.1 are expressed as 'per cm2 of leaf' rather than 'per leaf'. [1]
(c) Some crops are grown in controlled environments. Glasshouses are an example of a controlled environment. Fig. 3.3 shows a glasshouse where lettuces are growing.
Discuss the advantages of growing crops in glasshouses. [6]
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(a) Outline the reasons why large mammals, such as some species of rhinoceros, are endangered.
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(b) In 2013, Cincinnati Zoo in the USA announced that they were hoping to breed together rhinoceros that were brother and sister as part of their captive breeding programme.
(i) Discuss the problems that using such closely related animals might have for the conservation of rhinoceros.
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(ii) Captive breeding programmes often use artificial insemination.
Outline the process of artificial insemination.
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[Total: 10]
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500
(a) Table 5.1 shows four functions of the human gas exchange system. Complete Table 5.1 by identifying the part of the human gas exchange system that carries out each function.
Table 5.1
| function | part of the human gas exchange system |
| --- | --- |
| contracts to decrease air pressure in the lungs | |
| allows air to flow between the larynx and the lungs | |
| contracts to lower the ribs in forced expiration | |
| site of gas exchange | |
[4]
(b) Scientists investigated the effect of increasing carbon dioxide concentration in the air on the rate and depth of breathing. The people who took part in the investigation were healthy volunteers.
The people breathed atmospheric air containing 0.04% carbon dioxide for five minutes. They then breathed air containing 2% carbon dioxide for five minutes and then returned to breathing atmospheric air for a further five minutes.
The results are shown in Fig. 5.1.
[Image_Fig5.1]
Describe the effects of changing the carbon dioxide concentration of the air on the rate and depth of breathing, as shown in Fig. 5.1.
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[4]
(c) Complete the sentences by writing the appropriate word or phrase in the spaces provided.
During physical activity the carbon dioxide concentration in the blood increases. The reason for this is an increase in the rate of ............................. that occurs in the ........................................ in muscle cells. The increase in the concentration of carbon dioxide in the blood is detected by the ........................................ , which increases the rate and depth of breathing so that carbon dioxide can be ........................................ from the body. This is important because carbon dioxide is a ........................................ substance and can cause harm if it accumulates.
[5]
[Total: 13]
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There are four blood groups in the ABO system in humans: A, B, AB and O.
The gene that determines blood group has three alleles: $I^A$, $I^B$ and $I^o$.
(a) Parents with the genotypes $I^A{}^o$ and $I^B{}^o$ are planning to have more children.
Complete the genetic diagram to determine the probability that the next child will have blood group O.
parenteral blood groups A B
parenteral genotypes $I^A{}^o$ $I^B{}^o$
[Table]
Punnett square
phenotypes of the children ..........................................................
probability that the child will have blood group O .............................................. [4]
(b) Explain why the ABO blood group system is an example of co-dominance.
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(c) Fig. 6.1 shows the percentages of the global population with the four different blood groups in the ABO system.
[Image]
With reference to Fig. 6.1, explain why the ABO blood group system is an example of discontinuous variation.
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[Total: 8]
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