21'

• Which is the equation for photosynthesis? [1 mark]

  C6H12O6 + 6O2 → 6 CO2 + 6 H2O

  6 CO2 + 6 H2O → C6H12O6 + 6O2

  6 H2O + 6O2 → C6H12O6 + 6 CO2

  6O2 + 6 CO2 → C6H12O6 + 6 H2O

  6 CO2 + 6 H2O → C6H12O6 + 6O2
• (Rate fo photosynthesis) What was the independent variable in this investigation? [1 mark]

  Distance of the pondweed from the lamp

  Length of the piece of pondweed

  Number of bubbles of gas produced

  Time taken to collect the gas

  distance of the pondweed from the lamp
• The lamp gets warm when it is on. This causes the temperature of the water box to increase.

  Explain how an increase in temperature would affect the results of this investigation. [2 marks]


  - bubbles (of gas) would be produced faster

  - (because) enzymes work faster
• Suggest two improvements to the investigation so the results would be more valid. (Rate of photosynthesis) [2 marks]

  - measure the volume of gas produced

  - use the same bulb / lamp
• Describe how to test a sample of food for protein, starch and sugar. Give the colours that would be seen if the food sample contained protein, starch and sugar. [6 marks]

  PROTEIN-

  - grind up food

  - add Biuret (reagent / solution)

  - turns purple / lilac

  STARCH-

  - add iodine (solution)

  - turns black / blue-black / dark blue

  SUGAR-

  - grind up food •

  - mix with water

  - add Benedict's (reagent / solution)

  - heat mixture (≥ 65 °C) (water bath)

  - turns (brick) red / orange
• Fermentation is an exothermic reaction. What does exothermic mean? [1 mark]


  releases energy (to the surroundings)
• The spread of malaria is reduced by releasing sterile mosquitos into the environment. Explain how releasing sterile mosquitos reduces the spread of malaria. [2 marks]

  - reduces breeding / reproduction (in mosquitos)

  - (so) fewer mosquitos to bite people
• Pathogens also cause diseases in plants. Figure 4 shows a rose black spot fungal spore and a tobacco mosaic virus.

  Name the piece of equipment used to view the virus.

  electron microscope
• Explain why plants infected with tobacco mosaic virus grow slowly. [3 marks]

  - less chlorophyll in leaves

  - (so) reduced photosynthesis

  - (so) less glucose produced so less amino acids / proteins / cellulose made
• Which blood vessel transports blood with the highest oxygen concentration into the heart? [1 mark]

  pulmonary vein
• Which blood vessel transports blood at the highest pressure? [1 mark]

  aorta
• What is the correct order for blood flowing through the heart to the lungs? [1 mark]

  left atrium → left ventricle → pulmonary artery

  left atrium → left ventricle → pulmonary vein

  right atrium → right ventricle → pulmonary artery

  right atrium → right ventricle → pulmonary vein

  right atrium → right ventricle → pulmonary artery
• Statins and stents are two treatments used to reduce the risk of someone having a heart attack. Evaluate the use of statins compared with the use of a stent to reduce the risk of a heart attack. [6 marks]

  statin:

  A- decrease blood cholesterol, cheaper than stent

  D- effects take time, needs long term

  stent:

  A- immediate effect, rapid recovery from operation

  D- risk of infection from op./ surgery
• Many people who survive a heart attack get out of breath easily when they exercise gently. Explain why heart attack survivors get out of breath easily. [4 marks]

  - heart (muscle) cannot contract / pump as effectively / powerfully

  - (so) less blood pumped out of heart or to body (on each beat / contraction)

  - (so) less oxygen (reaches cells / body) for (aerobic) respiration

  - (so) breathing rate increases to supply more oxygen
• Explain why stem cells are used to make the patches. [2 marks]

  - they're undifferentiated

  - (therefore) can form heart (muscle) cells
• Give two advantages of using stem cells made from the person's own cells, rather than using embryonic stem cells. [2 marks]

  - cells will not be rejected

  - no risk of damage to embryo
• Describe how water is transported from the soil to the atmosphere through a plant. [4 marks]

  - (absorbed from soil) by osmosis through root hair (cells)

  - travels through xylem (vessels) to the leaves

  - lost through stomata (to atmosphere)

  - idea of driven by evaporation / transpiration
• Dissolved sugars are moved through a plant in phloem tissue. What is the name of the process that moves dissolved sugars through phloem tissue? [1 mark]

  translocation
• Explain one way sieve tube cells are specialised for their function. [2 marks]

  - have pores in the end walls

  - (so) dissolved sugars / food / contents can move from cell to cell
• What does the structure of the companion cells suggest about the process that moves dissolved sugars through the phloem tissue? Give a reason for your answer. [2 marks]

  - Is an active process

  - (as) cells have many mitochondria
• Describe why it is important that dissolved sugars are moved both upwards and downwards in a plant. [3 marks]

  - are made in the leaves by photosynthesis

  - all cells / tissues need sugar for respiration

  - transported to meristems for growth / cell division / mitosis