exam questions i got wrong Flashcards
(42 cards)
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
