KS4 Metabolism

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KS4 Metabolism, Exercise & Health
Learning Objectives

4.2.1 Aerobic and anaerobic respiration

Students should:

  • Be able to describe cellular respiration as an exothermic reaction which is continuously occurring in living cells and that the energy transferred supplies all the energy needed for living processes.
  • Know that respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to transfer energy.
  • Be able to compare the processes of aerobic and anaerobic respiration with regard to the need for oxygen, the differing products and the relative amounts of energy transferred.
  • Know that organisms need energy for:
    - chemical reactions to build larger molecules
    - movement
    - keeping warm.
  • Know the word equation for aerobic respiration:
    glucose + oxygen  →  carbon dioxide + water
  • Know the chemical equation for aerobic respiration: (HT only)
    C6H12O6 + 6O2  →  6CO2 + 6H2O
  • Know the word equation for anaerobic respiration in muscles:
    glucose → lactic acid
  • Know that as the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration.
  • Know the word equation for anaerobic respiration in plant and yeast cells: 
    glucose →   ethanol + carbon dioxide
  • Know that anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks.

4.2.2 Response to exercise

Some content is Higher Tier only.

Students should:

  • Know that during exercise the human body reacts to the increased demand for energy.
  • Know that the heart rate, breathing rate and breath volume increase during exercise to supply the muscles with more oxygenated blood that is needed for the increased cellular respiration to transfer more energy to meet the demand.
  • Know that if insufficient oxygen is supplied anaerobic respiration takes place in muscles.
  • Know that the incomplete oxidation of glucose causes a build-up of lactic acid and creates an oxygen debt.
  • Know that during long periods of vigorous activity muscles become fatigued and stop contracting efficiently.
  • Know that one cause of muscle fatigue is the build-up of acid in the muscles.
  • Know that the oxygen debt must be ‘repaid’ once exercise stops causing deep breathing for some time.
  • Be able to investigate the effect of exercise on the body.
  • Know that blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose. (HT only)
  • Know that oxygen debt is the volume of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells. (HT only)

4.2.3 Metabolism

Students should:

  • Know that metabolism is the sum of all the reactions in a cell or the body.
  • Know that the energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules.
  • Know that metabolism includes:
    - conversion of glucose to starch, glycogen and cellulose
    - the formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids
    - the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins
    - respiration
    - breakdown of excess proteins to form urea for excretion.

2.2.5 Health issues

Students should:

  • Know that Health is the state of physical and mental wellbeing.
  • Know that diseases, both communicable and non-communicable, are major causes of ill health, and that some diseases can interact.
  • Know that other factors including diet, stress and life situations may have a profound effect on both physical and mental health.
  • Know that defects in the immune system mean that an individual is more likely to suffer from infectious diseases.
  • Know that Viruses living in cells can be the trigger for cancers.
  • Know that immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
  • Know that severe physical ill health can lead to depression and other mental illness.
  • Be able to translate information between graphical and numerical forms, construct and interpret frequency tables and diagrams, bar charts and histograms, and use a scatter diagram to identify a correlation between two variables.
  • Be able to understand the principles of sampling as applied to scientific data.

2.2.6 The effect of lifestyle on some non-communicable diseases

Students should:

  • Be able to explain the effect of lifestyle factors including diet, alcohol and smoking on the incidence of non-communicable diseases at local, national and global levels.
  • Know that risk factors are linked to an increased rate of a disease and that they can be aspects of a person’s lifestyle or substances in the person’s body or environment.
  • Know that a causal mechanism has been proven for some risk factors, but not in others.  Examples include:
    - The effects of diet, smoking and exercise on cardiovascular disease.
    - Obesity as a risk factor for Type 2 diabetes.
    - The effect of alcohol on the liver and brain function.
    - The effect of smoking on lung disease and lung cancer.
    - The effects of smoking and alcohol on unborn babies.
    - Carcinogens, including ionising radiation, as risk factors in cancer.
  • Be able to explain the human and financial cost of these non-communicable diseases to an individual, a local community, a nation or globally.
  • Interpret data about risk factors for specified diseases.
  • Be able to understand the principles of sampling as applied to scientific data in terms of risk factors.
  • Be able to translate information between graphical and numerical forms.
  • Be able to extract and interpret information from charts, graphs and tables.
  • Be able to use a scatter diagram to identify a correlation between two variables.

2.2.7 Cancer

Students should:

  • Be able to describe cancer as a result of changes in cells that lead to uncontrolled growth and division
  • Know that Benign tumours are growths of abnormal cells which are contained in one area, usually within a membrane. They do not invade other parts of the body.
  • Know that malignant tumour cells are cancers and that they invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours.
  • Know that Scientists have identified lifestyle risk factors for various types of cancer including smoking, obesity, common viruses and UV exposure.
  • Know that there are also genetic risk factors for some cancers.

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