4/5/6 markers

• explain how low blood components cause tiredness, infections and bleeding?

  TIREDNESS- less red blood cells means less haemoglobin carrying oxygen so less respiration, less energy therefore anaerobic respiration occurs causing lactic acid and muscle fatigue

  INFECTION- less white blood cells means less antibodies/phagocytosis so less pathogens killed

  BLEEDING- fewer platelets meaning less blood clots
• why is there a difficulty digesting fat if there is a tumour blocking the vein from gall bladder to small intestine?

  • Less bile therefore less emulsification and less surface area for lipase to break down fat into tiny droplets
  • pH isnt neutralised so lipase isnt at its optimum to break down fat
• explain the human response to exercise?

  • HEART RATE: increases so more oxygenated blood to muscles/lungs is provided to ensure more glucose for energy and to remove excess/waste CO2 and lactic acid.
  • BREATH RATE: to ensure more oxygen to the blood and CO2 is removed for respiration and energy for muscle contraction.
  • ANAEROBIC RESPIRATION: lactic acidddd
• how are human lungs adapted for efficient gas exchange?

  1. ALVEOLI: 75m3 surface area to volume ratio, have a good blood supply and capillaries one cell thick to maintain a concentration gradient, thin moist walls for a shorter diffusion
  2. LUNGS: ventilated for O2 and rid of excess CO2
• what are the effects of liver failure?

  • NO BILE: less emulsification/neutralisation so slower digestion and enzymes cant function so you loose weight.
  • LACTIC ACID: isnt oxidised and is toxic so causes muscle fatigue and pain, swollen liver
  • PROTEINS: and amino acids arent deamminated so no urea but also no ammonia produced
• why may a leaky valve make exercise hard?

  • backflow meaning lood in the heart instead of oxygen going to the body cells and muscles so less aerobic respiration for energy and muscle contraction
  • anaerobic respiration occurs which creates lactic acid build and muscle fatigue
• evaluate mechanical vs biological valves?

  M: longer lasting up to six years, needs anticoagulant drugs to prevent blood clots and can cause difficulties if forgotten or not taken correctly

  B: no additional medication required, ethical issues due to use of animal tissue. Valves may harden and need operation, if rejected they need immunosupressants

  BOTH- readily available.
• why will an axolotl die in a low oxygen concentrated water supply?


  The concentration gradient of oxygen is shallower so there s less oxygen diffusion into the blood. Less aerobic respiration so there is less energy and less metabolism
• How will pancreatic cancer lead to a loss of weight?

  Reduced enzyme production so food isnt broken down or digested fully so less glucose is absorbed into the bloodstream so more fat is used in metabolism. Amino acids arent available for protein repair.
• explain how villi and alveoli are adapted to absorb molecules into their bloodstream?

  STRUCTURAL- large surface area due to microvilli and alveolar walls are folded, many capillaries and good blood supply to maintain a concentration gradient, mitochondria for energy

  FUNCTIONAL- maximises diffusion of gases and provides short distance for diffusion
• explain how human circulatory system supplies O2 to tissues and removes waste products?

  • double circulatory system meaning higher blood pressure and greater blood flow to tissued
  • specialised cardiac muscles with long protein filaments which slide past each other to shorten cells for blood contraction
  • blood to lungs via PA for O2 into alveoli, PV returns blood to heart and pumped to body via aorta
  • RBC carry haemoglobin so more oxygen
  • SA, thin walls, less waste CO2 into plasma
  • valves prevent backflow
• why does an increase in potassium ions cause stoma to open?

  • potassium ions increase concentration< water moves into the cells by osmosis, cell swells unevenly so stoma opens as inner wall is more flexible than the outer
• how does a test strip show pregnancy?

  1. as urine passes through reaction zone, HCG binds to mAbs in reaction zone with blue beads/dye
  2. HCG binds to immobilised HCG in reaction zone the other ones pass to control zone and bind and show two blue lines to show positive result
• 2 reasons for yellow leaves and stunted growth other than nitrates?

  • lack of mg, not enough chlorophyll for photosynthesis therefore less glucose to make proteins for growth
  • TMV causes chlorosis/discolouration so not enough glucose to give energy for growth
  • infected by aphids
• investigate effect of exercise on smokers?

  1. get two groups of people - non smokers vs smokers at least five people in each group
  2. get each person to do a named exercise
  3. control - age, lifestyle, gender, time ect
  4. calculate increase in heart rate
  5. compare and plot a graph!!!
• why will a diabetic person loose water?

  the blood is more concentrated so water moves out the cells via osmosis through a partially permable membrane
• what is a double circulatory system?

  A circulatory system in which blood passes through the heart twice in one complete circuit of the body.
• what are the advantages vs disadvantages of a kidney transplant rather than dialysis?

  • ADVANTAGES: no need for long hospital visits, no need to control diet, cheaper for NHS, maintains correct concentration of substances in the body
  • DISADVANTAGES: may be rejected and have to take immunosuppressants, donor may not be available, doesnt last all your life, risk of infection from surgery
• how does our thermaregulatory system react to our bodies being too cold?

  1. vasoconstriction, less blood flow to the skin so less energy is lost to the surroundings.
  2. shivering muscle contraction releases energy
  3. hairs stand up to keep us warm
• 3 ways coordination centre is different in endocrine vs nervous system?

  1. slower
  2. longer lasting
  3. uses hormones instead of electrical impulses
• how do hormones control menstrual cycle?

  1. FSH produced by pituitary gland stimulates egg maturity
  2. oestrogen released from ovary inhibits FSH and stimulates LH
  3. LH stimulates ovulation
  4. progesterone inhibits FSH and LH
  5. progesterone and oestrogen maintain uterus lining
• how is light detected in the eye?

  1. receptor cells inn retina are sensitive to light
  2. impulse passes along sensory neurone
  3. along optic nerve
• describe evolution and variation..?

  1. mutation in gene randomly or due to chance causes a new protein therefore variation
  2. those with the mutation are the most successful competitors for food and survival of the fittest occurs via natural selection where weakest die out the most successful from being eaten by predators and eating food breed
  3. breed and pass these genes off to offspring repeated over many generations
• explain how an eye adjust to focus on a nearer object?

  1. cilliary muscles contract and have a smaller diameteer
  2. suspensory ligaments loosen
  3. lens thickens/fattens/curves and becomes convergent( refracts more light)
  4. light rays are now focused on the retina
• why someone with hyperopia finds it hard to see nearer objects clearly?

  • eyeball is too short so image focuses behind the retina
• how can spectacle lenses correct hyperopia?

  • convex lens
  • light rays refracted more inwards
• why is a computer more accurate than a stopwatch?

  • computers are more precise as stopwatches cant count milliseconds
• describe what happens to the eye in dim lighting?

  pupils dilate since circular muscles in the iris relax and radial muscles contract
• describe how pituitary glands and kidneys help prevent water loss?

  higher concentration of blood means more ADH release meaning increased permeability of kidney tubules to water so increased water reabsorption
• explain how insulin and glucagon control blood glucose levels?

  after meals blood glucose increases causing insulin secretion which makes glucose enter liver/cells/muscles to convert it to glycogen for storage in the liver

  blood glucose levels too low secretes glucagon which turns glycogen into glucose
• why is protein not found in urine of healthy person?

  molecules are too large and cant pass through filtration membrane
• why is glucose not found in the urine of a healthy person?

  glucose is reabsorbed, all of it.
• explain why urea and sodium ions are found in urine and why their concentration is higher on a hot day rather than a cold day?

  small molecules that can pass through membrane/filter and not all are reabsorbed, ore water is reabsorbed on a hot day as sweating concentrates urine and loss in sweat
• what is a hormone?

  chemical messanger secreted by endocrine system/ gland which targets specific organs when released into the blood
• suggest what would happen to the body of someone with hyperthyroidism?

  too much thyroxine released into the blood increasing basal metabolic rate causing increase in rate of respiration,breakdown of proteins and formation of bigger molecules
• how does phototropism in a plant help it to survive?

  leaves/plant recievs more light so more photosynthesis therefore more glucose
• describe structure of nucleotides?

  • a backbone made of a sugar and phosphate
  • attached to one of four bases - A C T G
• why is sexual reproduction an advantage?

  • genetic variation in offspring
  • so better adapted to survive
  • can escape adverse event( disease)
  • more offspring so higher probability will survive
• explain how a change in an amino acid can change a proteins function?

  different protein made, active site has changed so substrate cant fit
• describe selective breeding?

  • find woman with highest yield and desirable production same with male
  • breed so they pass down the desirable gene over to offspring for many generations