BY4-June 2013 Flashcards
Suggest a reason for the slower speed of response by jellyfish.
Only have a nerve net/no CNS.
Nerve fibres non-myelinated.
Narrower axons.
Name the substance that plants use to detect day and night length.
Phytochrome.
Suggest two density I dependant factors, which might prevent numbers of red kites to continue to rise.
Nesting sites.
Source of food.
Mates.
Disease.
Suggest on density independent factor that might cause the population of the red kite in Wales to crash in the future.
Deforestation.
Explain how carbon dioxide is used in the production of glycerate-3-phosphate.
RuBP and carbon dioxide are fixed together. RuBP carboxylase (RUBISCO) catalysed the reaction. Unstable 6C compound formed, splits into two 3C.
State the general role of muscles and glands in simple reflexes.
Effectors carry out the response/react to stimulus.
Describe how glycerate-3-phosphate is converted to triode phosphate.
Glycerate 3 phosphate reduced using reduced NADP.
ATP also required to supply energy.
Reduced NADP and ATP from light dependant reactions.
State why only some of the triode phosphate produced by the Calvin Cycle can be used to produce the hexose phosphate.
Some triode phosphate needed to regenerate RuBP.
Suggest how many times the Calvin cycle must occur to produce one molecule of glucose.
Six times.
Suggest two reasons for the the use of a sparser in fermenters.
Improves aeration.
Helps to mix the contents.
Improves contact with nutrients.
Suggest why the pH probe is needed.
Monitor pH.
Used to determine whether acid or alkaline must be added to maintain optimum pH for growth.
State one waste gas that will need to be removed if the microorganism is an obligate aerobe.
Carbon dioxide.
Suggest why its necessary to warm contents at start and cool towards end.
Heated at the start to speed up enzyme reactions/growth.
Removal of heat produced by respiration/more microbes at the end so more respiration and heat.
Suggest reasons for preventing the fermenter becoming contaminated with other microorganism.
Competition for nutrients.
Lower yield.
Toxic products.
Contamination of product.
Explain the reasons for reduced NAD being required to maintain a proton gradient.
Reduced NAD supplies protons.
And brings high energy electrons.
Electrons supply energy for proton pumping.
Outline the pathway for the production of triose phosphate in glycolysis.
Glucose is phosphorylated by ATP.
Two phosphorylations/production of hexose biphosphate.
Hexose biphosphate is split from 6C to 3C.
Explain the biomechanical reasons for carrying out the reaction, despite the fact that lactate is toxic in high concentrations.
Allows reduced NAD to be converted back into NAD without oxygen.
Allows for ATP production without oxygen.
Allows glycolysis/substrate level phosphorylation to continue.
No O2 to act as final hydrogen acceptor, must use pyruvate.
Explain in terms of movement of ions, what causes the rise in membrane potential.
(Voltage gated) sodium channels open.
Sodium ions rush in/sudden influx.
State the name given to the rapid fall in membrane potential.
Repolarisation.
Suggest how cardiac muscle fibres would respond when the voltage across the membrane rises.
Contraction.
Consider the ethics of killing a frog to obtain cardiac muscle fibres by giving one argument in favour and one against.
Frog has right to life, causes suffering and distress to frog.
Benefits to medicine/health of heart research.
Name the vessel that brings blood to the kidney.
Renal artery.
Describe two structural features of glomeruli that allow ultrafiltration to occur.
Many gaps in the endothelium.
Basement membrane with pores, acting as molecular sieve.
Efferent arteriole has smaller diameter than afferent.
Using your knowledge of processes occurring in the nephron, explain the difference in glucose concentration between glomerular filtrate and urine.
All glucose selectively reabsorbed.
Reabsorption in the proximal convoluted tubule.
Reabsorption by active transport.
Describe the role of the nephron an collecting duct in achieving this increase in concentration.
Water reabsorbed from filtrate.
Less urea reabsorbed.
Sodium ions reabsorbed in proximal convoluted tubule.
Therefore water reabsorbed by osmosis in proximal convoluted tubule.
Active transport of sodium ions in the ascending limb of loop of Henle.
Descending limb permeable, ascending limb impermeable.
Hypertonic conditions in the medulla.
Therefore water reabsorbed in the collecting duct.
Suggest an advantage to mammals of excreting urine with a high concentration.
Less water lost in urine.
Reduces risk of dehydration.
The concentration of sodium ions in the urine of a person varies. The concentration is affected by the level of a hormone. Name this hormone and explain how it affects the concentration of sodium ions in the urine.
ADH.
Increases reabsorption of water as increases the permeability of the collecting duct to water so increases the ion concentration.
