Syllabus Edition
First teaching 2014
Last exams 2024
1 markDefine hydrophilic.
2 marksState two advantages of a carbon atom being able to form four bonds to neighbouring atoms.
3 marksList three carbon compounds that living organisms are based upon.
1 markState which part of metabolism is occurring at II in the flowchart below.
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1 markState the aspect of the molecular behaviour of water that is used to explain why it is highly important to living organisms.
3 marksTwo of the properties of water are its cohesive and adhesive forces.
Describe how these properties are useful to living organisms.
2 marksBoth water and methane are small molecules containing single covalent bonds between their atoms.
State two differences between these two molecules that make their physical properties very different.
2 marksList two physical properties, associated with their state of matter, that differ between water and methane.
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1 markDefine molecular biology.
1 markState the name of the compound that was synthesised artificially, providing evidence that living organisms are not required to produce organic compounds.
3 marksDraw a labelled diagram of a water molecule.
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2 marksIdentify which of the diagrams below is a lipid, giving one reason why.
2 marksDraw a molecular diagram of D-ribose.
2 marksList, using simplified notation, two of the chemical groups found in a generalised amino acid.
2 marksState, giving one reason, which diagram shows the structure of a saturated fatty acid.
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3 marksOne mark is available for clarity of communication throughout this question.
Outline the theory that states that organic molecules could only be derived from living systems.
5 marksDistinguish between anabolic and catabolic reactions.
Include one example of each reaction.
7 marksDescribe the properties of water molecules that enable them to transport metabolites, using four named examples.
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2 marksSuggest, with a reason, which label (I, II, or III) indicates a catabolic reaction.
1 markThe diagram in part (a) illustrates how life is based on certain biochemical compounds.
Identify which major group of carbon-containing compounds is dominant in this diagram.
3 marksFats and cholesterol are essential to structures and functions in the bodies of animals and therefore need to be transported in blood.
Discuss how these molecules are transported.
4 marksDraw a labelled diagram of a generalised amino acid.
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2 marksEastern collared lizards and pigs are two examples of animals that pant to keep cool.
Suggest how panting helps these animals to cool down.
2 marksMethane is a product of the incomplete breakdown of dead organic matter. Methane can be seen bubbling out of the water in volcanic springs.
Explain why, once methane has been produced, it bubbles off the water.
3 marksDraw a labelled diagram showing cohesive forces between three water molecules.
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2 marksOutline the significance of the surface tension of water to living organisms.
2 marksUsing your knowledge of the properties of water, explain why dilute aqueous solutions (eg. glucose solution) are clear.
3 marksExplain the relationship between the osmolarity of a solution and its water potential.
2 marksExplain how water's high specific heat capacity helps to keep environmental conditions constant for organisms.
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6 marksWater exists in all three of its physical states in Nature.
Give an example of each physical state of water that exists in Nature and how it affects organisms and ecosystems.
2 marksCompare and contrast the properties of methane and water.
2 marksExplain why a methane molecule (CH4) forms a tetrahedral shape.
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3 marksOne mark is available for clarity of communication throughout this question.
Multiple pieces of evidence are required for scientists to falsify theories.
Discuss the evidence that scientists used to falsify the theory of vitalism.
4 marksDeamination (the removal of an amino group from a molecule) and gluconeogenesis (the production of glucose from non-carbohydrate sources) are two reactions that occur in the liver.
From the information given, suggest with reasons, which metabolic reactions these are classified as.
8 marksExplain the properties of water that are key for the survival of an oak tree.
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Which property or properties (A, B, C) explain the ability of water to dissolve solutes?
Property A: Polarity of water molecules
Property B: High specific heat capacity of water
Property C: Hydrogen bonding
Describe the properties of carbon that make it an ideal element as the basis of living systems.
A group of students investigated the thermal properties of water. To do this, they poured hot water at 70°C into two thin plastic cups and measured the rate of cooling of each cup. The sides of one cup were covered with tissue paper soaked in hot water. The sides of the other cup were left uncovered. The temperature of the water in each cup was recorded with a thermometer every 2 minutes for 10 minutes. The results are shown in the graph below.
Other than the starting temperature of the water (70°C), give two conditions that must be kept the same for each cup throughout the experiment.
With reference to a thermal property of water, explain how the experiment in part c) can demonstrate the response of the human body to prevent overheating.
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Water plays a very important role within the cytoplasm of cells. Two properties of water that make it an important part of the cytoplasm of cells are its polarity and its ability to act as a universal solvent.
For each of these two properties, explain why this makes water important for the cytoplasm.
The relatively high specific heat capacity of water is of great biological significance to organisms.
State one example of how this property is biologically important.
With reference to bonding, explain how the relatively high specific heat capacity of water enables it to buffer temperature changes.
The diagram below shows three water molecules in close proximity to each other. Using a dotted line, draw a hydrogen bond between water molecules. Also use the symbols δ+ and δ- to indicate small electrostatic charges on the appropriate atoms.
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Distinguish between anabolic reactions and catabolic reactions.
Complete the table with tick marks (✓) in the appropriate boxes.
| Cellular reaction | Anabolic | Catabolic |
| Fats → fatty acids and glycerol | ||
| Accumulation of starch from sugars in plants | ||
| Anaerobic respiration in yeast cells | ||
| Hydrolysis of polypeptides into amino acids |
The diagram below shows part of a biochemical pathway that takes place commonly in cells.
Deduce whether the pathway is anabolic or catabolic and give evidence from the diagram for your answer.
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Compare and contrast the terms adhesion and cohesion in the context of water molecules in biological tissues.
The diagram shows a pond skater (or water strider).
Certain small animals such as pond skaters and fisher spiders can walk across bodies of water without breaking the surface.
Use your knowledge of water's properties to suggest how detergent pollution contaminating ponds and lakes can have a detrimental effect on these small animals.
Outline how vasodilation affects the volume of water lost as sweat in humans.
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One mark is available for clarity of communication throughout this question.
Explain the importance of hydrogen bonding in biological molecules.
Compare and contrast the structures of water (H2O) and methane (CH4) and use any structural differences to account for the differences in the two compounds' chemical and physical properties.
Explain how certain biological molecules are hydrophilic, some are hydrophobic and others are amphipathic. Use named molecules as examples in your answer.
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