SAMS Paper 1 Flashcards
Past Paper Questions
What process do plants use to move mineral ions into root cells?
Active transport
Describe how the water moves from roots to the leaves.
- by the transpiration stream
- in the xylem
A student collected data of the number of stomata on the upper and lower surface of the leaf. Describe how the student might have collected the data.
- mount epidermis on a slide
- count stomata in one area
- repeat in four more areas
- repeat method on other surface of leaf
- calculate mean
The plant has very few stomata on the upper surface of the leaf.
Explain why this is an advantage to the plant.
- less water lost
- so it does not wilt
All tools should be washed in disinfectant after using them on plants infected with TMV.
Suggest why.
to kill the virus
OR
to prevent virus spreading
Suggest how scientists can use a plant to produce many plants with the same genes.
take stem cells from the meristem
OR
tissue culture
Describe how you would test for the presence of glucose.
- heat the mixture and add a few drops of Benedict’s solution
- glucose turns the solution from blue to orange
TMV can cause plants to produce less chlorophyll. This causes leaf discolouration. Explain why plants with TMV have stunted growth.
- less photosynthesis because of lack of chlorophyll
- therefore less glucose made
- less energy released for growth
- because glucose is needed for respiration
- therefore less amino acids for growth
- because glucose is needed for making amino acids
Describe the ways the body prevents the entry of microorganisms.
- acid in stomach kills pathogens in food
- skin forms a barrier / produces antimicrobial secretions
- hairs in the nose trap (particles which may contain) pathogens
- trachea / bronchi has mucus which traps pathogens
Explain what drug testing must be done before a new drug can be used to treat people.
- pre-clinical trials of the new drug on live animals to test toxicity, dosage and efficacy
- clinical trials / test on healthy volunteers and patients at very low doses
- so that you can monitor for safety / side effects
- and only then do trials to find the optimum dosage and test for efficacy
- double blind trial / use of placebo
- which does not contain the new drug
- random allocation of patients to groups
- so no one knows who has placebo / the new drug
- peer review of data
- to help prevent false claims
Describe how glucose from the small intestine is moved to another cell.
- glucose is absorbed by diffusion into the bloodstream
- then blood delivers glucose to muscles in capillaries
Investigation of anaerobic respiration in yeast cells. Image: Yeast cells in sugar solution covered with a layer of liquid paraffin.
What is the purpose of the liquid paraffin?
to stop air getting in
What would expect the concentration of carbon dioxide to be during maximum rate of anaerobic respiration?
concentration of CO2 is high
Suggest an experiment to give a reproducible way to measure the rate of the reaction. Include any apparatus you would use.
- collect the gas with a measuring cylinder
- (volume collected) in a certain time using a timer
Compare anaerobic respiration in a yeast cell with anaerobic respiration in a muscle cell.
- yeast produces ethanol but muscles produce lactic acid
- yeast produces CO2 but muscles do not
- both release small amounts of energy
