paper 1 Flashcards
describe how energy for photosynthesis reaction is gained by plants
light is absorbed by the green pigment in leaves called chlorphyll
describe how movement of potassium oons into guard cells causes the stomata to open
- potassium ions increase the concentration of the solution
- water moves in by osmosis
- the cell swells uneavenly
- because the inner walls are less flexible than the outer walls
causes of anomolous results in pondweed experiment
- temparature changed
- there were different mass/length of pondweed
- there was air/oxygen in the syringe/measuring cylinder/apparatus
- pondweed had not acclimatised yet
why is percentage change used?
so that results can be compared
sources of error in potato osmosis experiment
- the concentration of the solutions
- the chips might not have been dried properly
- the accuracy of the balance
how does water move from roots to the leaves
- from the transpiration stream
- through the xylem (in the xylem)
why is having less stomata on the upper surface of the leaf an advantage? (2 marks)
- there is less water lost
- so it does not wilt
why is the surface of the potatos dried in osmosis experiment?
so that excess water does not contribute to the mass of the cubes
aseptic techniques for culturing microorganisms
- sterilise equipment
- use sterilised agar
- secure lid of petri dish with adhesive tape
- only lift lid of petri dish a little when setting up
ways the body prevnts entry of pathogens
- acid in stomach kills pathogens in food
- skin is a physical barrier and produces antimicrobial secretions
- hairs in nose trap pathogens
- trachea/bronchi has mucus which is sticky and traps pathogens
- bronchi have cilia which waft mucus to throat to be swallowed
how does less chlorphyll lead to stunted growth
- less photosynthesis as theres less chlorophyll
- this means less glucose made
- so less energy released for growth
- because glucose is needed for respiration
- and less amino acids/proteins/cellulose for growth
- as glucose is needed for making these
why is haveing less stomata an advantage to the plant?
- less water evaporates
- so the plant does not wilt
steps for drug testing
- preclinical trials of new drug on cells/tissue/live animals to test for toxicity, dosage and efficacy
- clinical trials to test on healthy volunteers at very low dosages
- to monitot safety and side effects
- then on volunteers with illness for trials to find the optimum dosage and test for for efficacy
- double blind trials and using a placebo which does not contain the new drug
- should be given randomly to patients so no one knows who has it
- then peer review of data to help prevent false claims
how is glucose moved from small intesitne to a muscle cell
- glucose absorbed by diffusion into bloodstream
- then blood delivers glucose to muscles in capillaries
how can cancer in stomach cause cancer in the liver
if the cancer is malignant then cancer cells can spread to other organs via the blood forming a secondary tumor
