PAST PAPER QUESTIONS B1 B2 B3 B4 B5 B6

• Monoclonal antibodies in pregnancy tests

  Urine passes through reaction zone

  hcg hormone binds to mobile antibody in reaction zone

  Passes up stick hcg hormone binds to immobilized hcg antibodies in result zone

  The other antibodie which do not attach to hcg

  bind to antibodies in control zone

  blue dye appears in both control and result zones to show positive result
• Explain why a tree might die if root of tree are damaged

  Less absorption of water

  Less water so lower rate of photosynthesis

  Less glucose is produced

  for respiration

  so less cellulose produced so fewer cell wall made

  so fewer amino acids produced to make new protein

  Cells lose turgidity
• Describe how a student could test cow's milk to show whether it contains protein and different types of carbohydrate


  To test for protein, use biruet. Add biuret into the cow's milk, if protein is detected cow's milk will go from blue to purple.

  To test for starch , use iodine. Add iodine into the cow's milk, if starch is detected in the cow's milk it will go from a orange to blue black.

  To test for sugar use benedict. Add benedict to the cow's milk, then heat it. Solution will go from light blue to a brick red
• Describe how the alveoli and villi are adapted to increase absorption


  Both have thin walls - short distance - reduce diffusion time

  Both have large surface area - maxmise diffusion

  Both have good blood supply - to maintain concentration gradient

  Both are in close proximity to blood supply - reduce diffusion time
• Describe how mitosis produce two genetically identical cells


  Chromosomes are doubled

  Then chromosomes are pulled apart

  Cell membrane divides to form two cells

  Set of chromosomes in each cell are identical
• Describe the effect of a partly blocked coronary artery in human body


  Reduced blood flow to heart

  Less oxygen to heart

  Less glucose to heart

  Less aerobic respiration in heart

  So more anaerobic respiration

  So less energy is released
• Explain how the immune system of animals respond to vaccination. The immune response in farm animals prevent an outbreak of food poisoning in humans


  Animals white blood cell produce antibodies

  Against salmonella

  Antibodies are specific to antigens

  So fewer toxins produced in humans
• Red blood cells are specialised animal cells. Compare the structure of a red blood cell with structure of plant cell

  Red blood contains haemoglobin, plant cells do not

  Plant cells have a nucleus, red blood cell doesn't

  Plant cell have a cell wall, red blood cell doesn't

  Red blood cell do not contain chlorophyll

  Red blood cell are shaped like a biconcave disc
• Explain why the red blood cell burst but plant cell doesn't

  Water moves in cell by diffusion

  Plant cells has a cell wall that prevents it from bursting
• Compare structure and function of xylem and phloem tissue

  Phloem involves translocation , xylem involves transpiration

  Xylem transports mineral ions and water, phloem transports dissolved sugars

  Xylem is made up of dead cells , phloem is made up of living cells

  Xylem cells release a chemical called lignin but phloem doesn't

  Both transport liquids

  Phloem have pores in their end walls and xylem do not have pores in their end walls
• Describe the process by which root hair cell absorb water and mineral ions from soil

  Water moves in by osmosis

  from a dilute solution

  to a more concentrated solution in soil

  through a partially permeable membrane

  Mineral ions move in my active transport

  from dilute solution

  to more concentration solution

  against concentration gradient
• Explain why plants with tmv have stunted growth


  Less photosynthesis because of lack of chloropyll

  so less glucose made

  less energy released for growth

  because glucose is needed for respiration
• Explain what testing must be done before this new drug

  Pre-clinical trials on cells/ tissue / animals

  to test for efficacy, dosage and toxicity

  clinical trials on volunteers and ebola patient at very low dose

  so that you can monitor for side effect

  and then do trials to find optimum dosage and test for efficacy

  use of placebo

  which doesn't contain new drug
• Describe how different types of organism defend themselves against pathogens

  Skin - produces sebum killing microbes

  nose - produces mucus

  trachea - mucus traps microbes

  stomach - produces hydrochloric acid which kills bacteria

  white blood cell - produce antibodies

  plant cell wall - difficult to penetrate
• Describe how human body prevents pathogens from entering, defent itself against pathogens

  stomach contains hydrochloric acid

  kills bacteria

  in food

  
  

  Immune system - white blood cell engulf pathogen

  antitoxin are produced

  antitoxin neutralise toxin

  antibodies are produced
• Describe how the scientist would use the protein to produce PVY monoclonal antibody

  Inject the protein into mouse

  Combine mouse lymphocyte with tumour cell to make hybridoma cell

  Find a hybridoma which make a monoclonal specific to PVY antibody

  Then scientists clones hybridoma to produce many cells to make antibody
• Explain why root hair cells contain mitochondria

  aerobic respiration occurs in mitochondria

  respiration releases energy which is used for active transport to transport ions from low concentration to high
• Evaluate the use of stem cells from a patient’s own bone marrow instead of stem cells from an embryo

  embryo advantage - painless technique, can treat many disease

  embryo disadvantage - may not work, death to embryo

  bone marrow advantage- no ethical issues, reliable technique

  they both can treat the disease

  disadvantage of both - risk of transfer of viral infection
• Explain why an axolotl may die in water with a low concentration of oxygen

  concentration gradient of oxygen is shallower

  therefore less oxygen diffuses into blood

  so less aerobic respiration occurs so less energy is released

  so less metabolism
• Explain how the villi and the alveoli are adapted to absorb molecules into the bloodstream.

  both have a large surface area

  villi have many microvilli

  alveolar walls are not flat

  to maximise diffusion

  both have many capillaries

  to maintain concentration

  both have thin walls

  to provide short diffusion distance
• Describe the route taken by oxygenated blood from the lungs to the body cells

  blood travels through the pulmonary vein

  blood enters left atrium

  blood enters the left ventricle

  blood leaves the heart THROUGH aorta
• Explain why a person with a leaking heart valve has difficulty exercising.


  backflow can occur

  less blood is pumped around the body

  less oxygen supplied to muscles

  so less aerobic respiration
• Evaluate the use of mechanical replacement heart valves and biological replacement heart valves.

  mechanical valves are - longer lasting, blood clots are more likely after surgery , patient has to take anti-clotting medication for the rest of their lives

  biological valve - no additional medication required, valve may harden, more likely to be rejected

  both are readily available
• Describe how the small intestine is adapted for efficient absorption.


  villi provide a large surface area

  villi are thin

  small intestine is very long, increasing time

  efficient blood supply to maintain concentration gradient

  cells have many mitochondria for aerobic respiration
• Describe how ions, water and sugar are obtained and transported through plants

  Translocation is the process by which substances like dissolved sugars are transported from leaves to plants in phloem cell

  Transpiration is the process by which water moves from the roots to the leaves. Water is lost here by evaporation in xylem cells. They involve osmosis

  Ions is transported by active transport in xylem cells

  Water is transported from roots to plants then is transported to the plant by process by translocation

  Translocation releases water of water vapour from roots to leaves to atmosphere
• Different parts of human digestive system help to break down molecules of fat so that they can be absorbed into body. How?

  Mouth mechanically breaks down food molecules into smaller molecules with saliva by chewing

  Then the stomach disperse the food molecules and fat by churring it

  The pancreas now produce enzyme called lipase, they act on fat in small intestine converting into fatty acids and glycerol

  Liver produces bile alkali, they emulsifies fat , increasing its surface area nad package fatty acids and glycerol into small water-soluble molecules