Unit 1 - Tuesday 12 January 2010 Flashcards
Use your knowledge of water potential to explain why these adults get diarrhoea when they drink milk. 2 marks
- The water potential is lower in the lumen
2. Water enters the lumen from the cells by osmosis
What are the products of lactose being catalysed by lactase? 1 mark
Lactose + Water = Glucose and Galactose
What type of reaction includes the addition of water? 1 mark
Hydrolysis
Describe how you could use the biuret test to distinguish a solution of the enzyme, lactase from a solution of lactose. 1 mark
- Add biuret solution
- Lactase will turn solution purple as it is an enzyme.
Explain the result you would expect with the enzyme in the biuret test. 1 mark
As lactase is an enzyme is reacts as it is a protein.
Describe the path by which oxygen goes from an alveolus to the blood. 2 marks
- Through alveolar epithelium
- Through capillary epithelium/endothelium.
Explain why people with miner’s lung have a lower concentration of oxygen in their blood. 1 mark
(Thicker alveolus wall)
- Diffusion pathway is longer
Describe how ventilation helps to maintain this difference in oxygen concentration. 2 marks
In the alveolus;
- Brings in the air containing a high concentration of oxygen.
- Removes air with a lower oxygen concentration.
Give one other way that helps to maintain the difference in oxygen concentration. 1 mark
Circulation of blood
Coal mining in Britain had been dramatically reduced by 1990.
Some scientists concluded that the rise in reported cases of miner’s lung after 1992 shows that the disease takes a long time to develop.
Evaluate this conclusion. 2 marks
- Graph shows fluctuations
- Correlation does not mean causation as other factors may be the reason for miners lung.
Methotrexate is a drug used in the treatment of cancer. It is a competitive inhibitor and affects the enzyme folate reductase.
Explain how the drug lowers the rate of reaction controlled by folate reductase. 2 marks
- Methotrexate has a similar structure to substrate.
- Binds to the complementary active site.
- Less E-S complexes can form.
Methotrexate only affects the rate of the reaction controlled by folate reductase. Explain why this drug does not affect other enzymes. 1 mark
- Methotrexate is only similar shape to specific substrate so only fits into this active site.
There are large numbers of mitochondria in this cell. Explain how these organelles help the cell to absorb the products of digestion. 2 marks
- Site of aerobic respiration where ATP is produced.
- Active transport occurs where it goes against the concentration gradient.
Coeliac disease is a disease of the human digestive system. In coeliac disease, microvilli are damaged.
Although people with coeliac disease can digest proteins they have low concentrations of amino acids in their blood.
Explain why they have low concentrations of amino acids in their blood. 2 marks
- Reduced surface area so less absorption.
- Membrane bound enzymes less effective; so proteins not digested.
The students gave their results as a ratio. What is the advantage of giving the results as a ratio? 2 marks
- Allows comparison
- Idea that discs had a different starting mass
