paper 1 - exam style questions

• Eating food containing Salmonella bacteria can cause illness. Two symptoms of infection by Salmonella are vomiting and diarrhoea. What causes these symptoms?

  toxins / poisons (secreted by / from / in bacteria)
• Give two ways a person with a mild infection of Salmonella can help prevent the spread of the bacteria to other people.


  any two from: • wash hands after using toilet / being sick or wash hands before preparing / handling food or do not prepare food (whilst infected) • isolate yourself • disinfect clothes / surfaces • do not share utensils / cutlery / towels
• In very serious infections of Salmonella, a doctor can prescribe drugs to kill the bacteria. What type of drug can the doctor prescribe to kill the bacteria?

  antibiotics
• A person with AIDS may take longer than a healthy person to recover from a Salmonella infection. Explain why.

  immune system is damaged / weakened or immune system doesn’t function properly white blood cells cannot kill bacteria / Salmonella (as effectively)
• Salmonella bacteria can be transmitted from chickens to humans. Chickens can be vaccinated to prevent the transmission of Salmonella bacteria to humans. Suggest one other way farmers could prevent the transmission of Salmonella from chickens to humans.


  any one from: • (give chickens) antibiotics • don’t sell infected chickens / eggs • keep infected chickens isolated / indoors • slaughter the infected chickens
• What measurement would the scientist need to take to calculate the area where no bacteria were growing?

  radius (of area with no bacteria growing)
• The scientist showed the results to the restaurant owner. Both cleaning liquids cost the same per dm3. Suggest one other factor the restaurant owner should consider when choosing which cleaning liquid to use.


  any one from: • toxicity / side / health effects • effect on other types of bacteria / pathogens • interaction with other cleaners • ease of use • dilution factor of each cleaner (vs. cost) • time cleaner is effective for
• One metabolic reaction is the formation of lipids. Give one other metabolic reaction in cells.


  any one from: • respiration • formation of proteins • formation / breakdown of glycogen • breakdown of (excess) protein or formation of urea • photosynthesis or formation of glucose / starch (in plants)
• The circulatory system is composed of the blood, blood vessels and the heart. Urea is transported in the blood plasma. Name two other substances transported in the blood plasma.


  any two from: • carbon dioxide • water • glucose • amino acids • lactic acid
• Some athletes train at high altitude. Training at high altitude increases the number of red blood cells per cm3 of blood. Explain why having more red blood cells per cm3 of blood is an advantage to an athlete.


  more haemoglobin (therefore) more oxygen can be carried / transported (for) more (aerobic) respiration of muscle (cells) or more energy released for muscle (cells)
• Which two blood vessels carry deoxygenated blood?

  pulmonary artery vena cava
• Compare the structure of an artery with the structure of a vein.


  any three from: • arteries have a thicker layer of muscle (tissue) or veins have a thinner layer of muscle (tissue) • arteries have a thicker layer of elastic tissue or veins have a thinner layer of elastic tissue • arteries have a narrower lumen or veins have a wider lumen • arteries do not have valves and veins have valves
• A patient may be fitted with an artificial pacemaker. What condition may be treated using an artificial pacemaker?


  an irregular heart beat
• Explain why the masses of the eggs increased.

  (mass increased because) water entered by osmosis from a dilute solution in the beaker to a more concentrated solution in the egg (cell) through a partially permeable membrane
• Plants infected with aphids may show symptoms of magnesium deficiency. Magnesium deficiency symptoms include: • yellow leaves • stunted growth. Explain how a deficiency of magnesium could cause these symptoms.


  yellow leaves due to lack of chlorophyll (therefore) less / no light absorbed (by chlorophyll) (therefore) lower rate of / no photosynthesis (therefore) plant makes less / no sugar / glucose (therefore) plant converts less / no sugar / glucose into protein (for growth, so growth is stunted)
• A farmer thinks a potato crop is infected with potato virus Y (PVY). The farmer obtains a monoclonal antibody test kit for PVY. To make the monoclonal antibodies a scientist first isolates the PVY protein from the virus. Describe how the scientist would use the protein to produce the PVY monoclonal antibody.


  inject the protein / it into a mouse combine lymphocytes with tumour / cancer cells to make hybridoma (cells) find a hybridoma which makes a monoclonal antibody specific to PVY (the scientist) clones (the hybridoma) to produce many cells (to make the antibody)
• CF affects the cell membranes of cells in the lungs and digestive system. What is the function of the cell membrane?


  controls the movement of substances in / out of cell
• In a person with CF, cells lining the lungs and digestive system create too much mucus. explain why children with CF grow more slowly than children without CF.


  fewer (digestive) enzymes enter small intestine • (so) enzymes break down / digest less food • (therefore) less absorption of nutrients • (so) less glucose can enter the blood(stream) • (so) less (glucose) available for respiration • (less absorption of nutrients so) fewer amino acids can enter the blood(stream) • (so) less protein is made (for growth)
• What reagent is used to test for protein in cow's milk?

  Biuret reagent
• What color change indicates a positive test for protein using Biuret reagent?

  The solution turns from blue to lilac
• Which reagent is used to test for starch in cow's milk?

  Iodine solution
• What color change indicates a positive test for starch using iodine solution?

  The solution turns from orange/brown to blue/black
• What is the purpose of Benedict's reagent in testing cow's milk?


  To test for sugars
• What must be done to the milk after adding Benedict's reagent to test for sugars?

  The milk must be boiled or heated above 60 °C
• What color change indicates a positive test for sugars using Benedict's reagent?

  The solution turns from blue to brick red/brown/orange/yellow/green
• What are the steps to test cow's milk for protein, starch, and sugars?

  1. Test for protein:

  • Add Biuret reagent to milk
  • Positive: solution turns from blue to lilac

  1. Test for starch:

  • Add iodine solution to milk
  • Positive: solution turns from orange/brown to blue/black

  1. Test for sugars:

  • Add Benedict's reagent to milk and heat above 60 °C
  • Positive: solution turns from blue to brick red/brown/orange/yellow/green