exam questions i got wrong Flashcards
explain why bone marrow can be called a tissue
- group/collection of cells
- working together to produce blood cells
describe the process of active transport in root hair cells
- uptake of (soluble substances) / ions against the concentration gradient
- energy required FROM RESPIRATION
explain how cell enlargement is part of the growth process of a baby
- cells which are bigger take up more space
OR - cells have to get bigger or mature to divide
why is cell specialisation (differentiation) important for the development and growth of a healthy baby from a fertilised egg?
- babies need or are made of different types of cells or cells that have different functions
- as fertilised egg starts to divide each cell specialises to form a part of the body
suggest two reasons why viruses are not classed as cells
any two from:
- do not have a cell membrane
- do not have cytoplasm
- do not have a nucleus
- do not have mitochondria
- do not have ribosomes
suggest how the honey fungus spores travel from the roots of an infected gorse plant to the roots of a healthy gorse plant
in the soil water
describe how the human body prevents pathogens from entering and defends itself against pathogens in the body
skin:
- tough/dry/dead outer layer
- acts as a barrier
- sebum/oil on surface of skin repels pathogens
- scabs form over cuts OR scabs form a barrier
- platelets involved in forming clots
stomach:
- contains hydrochloric acid
- which kills bacteria
- in food OR in swallowed mucus
eyes:
- produce tears
- contains enzymes to kill bacteria
- tears are antisteptic
breathing system:
- trachea/bronchi/nose produce mucus
- mucus is sticky
- mucus traps bacteria
- mucus carried away by cilia
defends itself against pathogens inside the body:
- immune system/white blood cells
- WBCs engulf pathogens
- antitoxins are produced
- antitoxins neutralise toxins/poisons
- antibodies are produced
- antibodies help destroy pathogens
- memory cells are formed
- memory cells give a more rapid response if pathogen re-enters
a person with AIDS may take longer than a healthy person to recover from a salmonella infection
- immune system is damaged / weakened OR immune system doesn’t function properly
- white blood cells cannot kill bacteria as effectively
for second mark, allow:
- no/fewer antibodies so bacteria not killed
OR
- less phagocytosis so bacteria not killed
OR
- no/fewer antitoxins to counter toxins
explain how different types of organism defend themselves against microorganisms
animals:
- skin; sebum/oils to kill microbes, dead layer difficult to penetrate
- nose; hair keeps out dust and microbes
- trachea/bronchi; mucus traps microbes, cilia moves mucus
- stomach; hydrochloric acid kills bacteria
- white blood cells; produces antibodies, produces antitoxins, phagocytosis
plants:
- cell wall; tough/difficult to penetrate
- waxy cuticle; tough/difficult to penetrate
- dead cells/bark; fall off, taking pathogens with them
- production of antibacterial chemicals; kills bacteria
fungi:
- antibiotic production; kill bacteria
describe how injecting a monoclonal antibody for RSV helps to treat a patient suffering with the disease
- monoclonal antibody binds to virus OR binds to antigen on surface of virus
- antibody is specific to antigen
- white blood cells/phagocytes kill/engulf the virus
explain what testing must be done before this new drug can be tested to treat people with ebola
- pre-clinical trials of new drug on cells/tissues/live animals
- to test toxicity, dosage and efficacy
- clinical trials/test on healthy volunteers and ebola patients at very low doses
- so that you can monitor for safety/side effects
- and only then do trials to find optimum dosage and test for efficacy
- double blind trial/use of placebo
- which does not contain the new drug
- random allocation of ebola patients to groups
- so no one knows who has placebo/the new drug
- peer review of data
- to help prevent false claims
the use of antibiotics has not reduced the death rate due to all diseases to zero. suggest two reasons why
- antibiotics only kill bacteria
- some bacteria are resistant to antibiotics
- (correct) antibiotics not always used
- inherited/lifestyle diseases cannot be treated by antibiotics as not caused by bacteria
give two ways of reducing the negative effects of human activity on our ecosystems
- protecting rare habitats
- breeding programmes (for endangered species)
- regeneration (programmes)
- reintroduction of field margins / hedgerows
- awareness raising with politicians / public
- recycling
the student measured the growth of the duckweed by counting the number of leaves. suggest a better method of measuring the growth of the duckweed and explain why
- mass/weighing the plant
- length of roots
corresponding explanations:
e.g.
- incudes roots
- includes whole plant OR leaves vary in size OR length / mass / surface area is a continuous variable
explain why the death of the pond snail caused the concentration of carbon dioxide to increase after day 10
- snail is being decayed / decomposed / broken down
- by decomposers / bacteria (in pond water / snail)
- therefore respiration (of decomposers / bacteria) releases carbon dioxide
explain the lock and key theory of enzyme action
- active site of enzyme binds to the substrate because they are complementary (shapes)
- so substrate is broken down (into products)
- so products are released OR enzyme is not changed
there are many different types of lipase in the human body. why does each different type of lipase act on only one specific type of lipid molecule?
each active site has a specific shape (so only fits one type of lipid molecule)
explain why single-celled organisms like algae do not need complex structures for gas exchange
- cell has larger SA:volume ratio
- short diffusion distance
- diffusion via cell membrane is sufficient
OR - flow of water maintains concentration gradient
describe how scientists may use stem cells to create healthy lungs that aren’t rejected by a cf patient
- take stems cells from patient’s bone marrow
- remove / change / fix the cf gene
- create an embryo using these stem cells
explain how a very low number of blood components in the body can cause these symptoms
- tiredness
- frequent infections
- bleeding that won’t stop after skin is cut
tiredness
- fewer red blood cells
- less haemoglobin
- less oxygen transported around body
- less aerobic respiration takes place
- more anaerobic respiration takes place
- less energy released for metabolic processes
- lactic acid produced causes muscle fatigue
frequent infections
- fewer white blood cells / phagocytes / lymphocytes
- fewer antibodies produced
or
- less phagocytosis
- so fewer pathogens / bacteria / viruses killed
bleeding
- fewer platelets
- blood does not clot as easily
a person has a tumour blocking the tube leading from the gall bladder to the small intestine. explain why this person would have difficulty digesting fat
- no / less bile reaches small intestine
- less / no emulsification of fat
- so smaller surface area for lipase to break down fat
- pH of small intestine is not neutralised
- lipase not at optimum pH to break down fat
changes during exercise
heart rate increased
- to increase blood flowing to muscles
- to provide more oxygen
- to provide more glucose
- to remove carbon dioxide more quickly from muscles
- to remove lactic acid more quickly from muscles
breathing rate increased
- supplies more oxygen to lungs
- so more oxygen to blood
- more carbon dioxide removed
more oxygen to muscles
- needed for increased respiration
- to release energy
- for muscle contraction
anaerobic respiration occurs
- due to lack of oxygen
- causes a build-up of lactic acid
- oxygen debt
- muscle fatigue / pain
explain how human lungs are adapted for efficient exchange of gases by diffusion
many alveoli
- provide a larger SA:V ratio
capillaries are thin
OR capillary walls are thin OR one cell thick
- which provides short diffusion path (for oxygen / carbon dioxide)
breathing (mechanism) moves air in and out OR lungs are ventilated
- to bring in (fresh) oxygen
- to remove carbon dioxide
- to maintain a concentration / diffusion gradient
large capillary network OR good blood supply
- to remove oxygenated blood quickly
- to bring carbon dioxide to the lungs quickly
- to maintain a concentration / diffusion gradient
cirrhosis leads to liver failure. describe effects of liver failure on the human body
no bile made
- fats / lipids not emulsified
- SA of fats / lipids not increased
- pH of small intestine won’t be neutralised
- enzymes will not work effectively
- so may lose weight
lactic acid not broken down / oxidised
- accumulation of lactic acid in blood
- lactic acid is toxic
- oxygen debt higher
- so muscle pain / fatigue
protein / amino acids not broken down
- amino acids not deaminated
- not made into urea or will not form ammonia
- any ammonia formed is toxic
- so accumulation of amino acids in blood / body
glycogen stores will not be formed
- cannot control blood glucose
- so diabetes / coma / hyper/hypoglycaemia may occur
liver does not break down / remove other toxins
- toxins accumulate in blood
- body will be poisoned
- so pain or jaundice or swollen liver or portal hypertension occurs
explain why a person with a leaking heart valve has difficulty exercising
- backflow can occur OR some blood flows backwards
- less blood leaves the heart OR less blood is pumped around the body OR some blood stays in the heart OR reduced blood pressure OR reduced flow rate
- less oxygen supplied to muscles / cells
- so less aerobic respiration
- so less energy released
- so less efficient muscle contraction
- anaerobic respiration takes place
- less efficient removal of lactic acid OR lactic acid builds up OR oxygen debt occurs
- lactic acid building up causes muscle fatigue
- less efficient removal of carbon dioxide (from blood)
evaluate use of mechanical and biological replacement heart valves
mechanical valves
- longer lasting OR more durable
- blood clots are more likely
- patient has to take anti-clotting medication for the rest of their lives
- medication can lead to excessive bleeding
biological valves
- no additional medication required
- ethical issues surrounding use of animal tissue
- valve may harden
- more likely to need further operation OR another new valve
- more likely to be rejected
- more likely to need immunosuppressant medication
define the term double circulatory system
- blood is pumped to the lungs by one / right side of the heart
AND - blood is pumped to the body by the other / left side of the heart
explain why having only one ventricle makes the circulatory system less efficient than having two ventricles
- oxygenated and deoxygenated blood mixes
- so less oxygen reaches cells
explain why an axolotl may die in water with a low conc of oxygen
- conc gradient of oxygen is shallower
- less oxygen diffuses into blood
- less aerobic respiration occurs so less energy is released
- so less metabolism
- when anaerobic respiration occurs, lactic acid is produced and is toxic
monoclonal antibodies have been produced to treat pancreatic cancer. explain how the monoclonal antibody works to treat pancreatic cancer
- monoclonal antibody is attached to radioactive substance / toxin / drug / chemical
- monoclonal antibody will only attach to antigen on cancer cells
- so radioactive substance / toxin / drug / chemical will bind to cancer cells and stop them growing / dividing
explain how the villi and alveoli are adapted to absorb molecules into the bloodstream
- both have a large surface area
- villi have many microvilli
- alveolar walls are folded
- to maximise diffusion of gases / absorption of food molecules
- both have many capillaries / good blood supply
- to maintain concentration gradient / diffusion gradient
- both have thin walls / one cell thick walls
- to provide short diffusion distance for molecules to travel
- villi have many mitochondria
- to provide energy for active transport
- cells of the villi have microvilli
- to further increase the surface area
suggest two risk factors for coronary heart disease
- smoking
- high-fat diet
- lack of exercise
describe how the student could investigate the effect of pH on the breakdown of starch by amylase
- range of at least 3 pH values / use of buffer solutions
- control variables / keep amount or concentration of starch and amylase the same
- keep temperature the same using water bath
- use iodine test to make qualitative observations
- observe colour changes at different temperatures
- do repeats at each pH
explain how the human circulatory system is adapted to
- supply oxygen to the tissues
- remove waste products from tissues
- double circulatory system meaning higher blood pressure and a greater flow of blood to the tissues
- heart made of specialised muscle cells which have long protein filaments that can slide past each other to shorten the cell to bring about contraction for pumping blood
- heart pumps blood to lungs in pulmonary artery so oxygen can diffuse into blood from air in alveoli
- blood returns to heart via pulmonary vein where muscles pump blood to the body via aorta
- oxygen carried by RBCs which contain haemoglobin to bind oxygen and have no nucleus so there is more space available to carry oxygen
- arteries carry oxygenated blood to tissues where capillaries deliver oxygen to cells for respiration and energy release
- thin walls allow for easy diffusion to cells
- large surface area of capillaries to maximise exhange
- waste products removed
- blood goes back to heart in veins which have valves to prevent blackflow
what is an enzyme
- a catalyst / speeds up a reaction
- it is a protein OR it is specific
give two differences in the composition of blood in a vein than in an artery
- artery has more oxygen
- artery has more glucose
- artery has less carbon dioxide
- artery has less lactic acid
explain how a pregnancy test strip works to show a positive result
- urine passes through reaction zone
- HCG hormone binds to mobile HCG antibody in reaction zone
- passes up the stick and HCG hormone binds to immobilised HCG antibodies in the results window
- the other antibodies which do not attach to HCG
- bind to antibodies in control zone
- blue dye appears in both control and results zones to show positive result
give 2 uses of mobile antibodies
- pregnancy testing
- identify / locate specific molecules / other hormones
- locate blood clots
- diagnose / treat some cancers
candida albicans lives in the throat of infected patients. a sample is taken from the throat of a patient with a suspected candida albicans infection.
the sample is transferred onto a microscope slide.
describe how the mAbs and a fluorescent dye could be used to see any candida albicans pathogens on the slide.
- bind fluorescent dye to mAbs
- put bound fluorescent mAbs on the slide (and rinse off)
- mAbs will bind to Candida albicans / pathogens and show up under the microscope
the leaves of some plants release oils onto their surface. suggest how the production of oil on the surface of a leaf may protect the plant from aphids
- prevents aphids from attaching to leaf OR causes aphids to slide off lead
OR - idea that oil may harm / kill the aphid
explain how the nettle is adapted for defence and protection
- stinging hairs
- so this harms herbivores / stops animals eating them
- so less of the plant is removed / damaged
explain why having very few stomata on the upper surface of the leaf is an advantage to the plant
- less water loss
- so the plant does not wilt
