bioenergetics

• Word and symbol equation for photosynthesis

  carbon dioxide + water -> glucose + oxygen

  (light)

  6CO2 + 6H2O C6H12O6 + 6O2
• What is meant by the term 'limiting factor'

  A factor which is not at an optimum level to enable maximum rate

  of photosynthesis e.g. temperature
• Name the green pigment present in plant cells and state its role.

  Chlorophyll - to transfer energy from the environment and use it to synthesise glucose from carbon dioxide and water
• List three ways glucose produced by photosynthesis is used in plants

  Used for respiration; used to produce fats or oils for storage; used to produce amino acids for protein synthesis; converted into insoluble starch for storage; used to produce cellulose to strengthen cell walls.
• List three ways commercial farmers improve the environmental conditions in large greenhouses to maximise photosynthesis and ensure they make a profit.

  Increase the air temperature with heaters.

  Provide artificial lighting to supplement the sunlight and through the night.

  Increase the amount of carbon dioxide in the atmosphere by burning fossil fuels
• State how you test a leaf for starch and the positive result.

  Place leaf in boiling water, transfer to ethanol, wash in leaf in hot water, and add iodine - positive - blue-black.
• Describe an experiment to investigate how light intensity affects the rate of photosynthesis.

  Alter the light intensity by altering the distance of the lamp from the plant. Measure the numbers of bubbles produced within a set period.
• Why is photosynthesis an endothermic reaction?

  Takes in heat energy from the surroundings.
• Why do plants need nitrates from the soil?

  to make protein
• Describe the role of the palisade layer in the leaf.

  Where photosynthesis occurs - contain lots of chloroplasts to absorb light.
• Describe how water moves from the roots to leaves.

  Transpiration stream via the xylem.
• What is respiration?

  A chemical energy that releases energy.
• State what energy is needed for.

  Chemical reactions to build larger molecules, keeping warm and movement.
• Write down the word equation for aerobic respiration in a plant cell.

  glucose + oxygen -> carbon dioxide + water
• Write down the word equation for anaerobic respiration in an animal cell.

  Glucose -> lactic acid
• Write down the word equation for anaerobic respiration in a yeast cell

  glucose ->​ carbon dioxide + ethanol
• Why is fermentation of economic importance?

  Used in the manufacture of bread and alcoholic drinks.
• Describe three ways in which the body responds to vigorous exercise in order to ensure sufficient oxygen reaches the muscle cells.

  Increase in heart rate; increase in breathing rate and increase in breath volume.
• if exercise carries on for a long time, what happens to the muscles?

  Muscles become fatigued and stop contracting efficiently.
• Why is respiration described as an exothermic reaction?

  Respiration is an exothermic reaction because it transfers energy to the environment.
• In which organelle does respiration take place?

  mitochondria
• Describe how excess glucose is stored.

  Converted into glycogen and stored in the liver and muscles.
• What is meant by the oxygen debt?

  The amount of extra oxygen which is needed to remove all lactic acid from the body is known as the oxygen debt.