2019 Biology Mistakesm Flashcards
Why might have spread of malaria decreased
Improvements to healthcare so can roll out vaccination programmes
How does you body and immune system prevent pathogens from entering and causing harm? (6marks)
skin
• tough / dry / dead outer layer
• skin acts as a barrier
• sebum / oil on (surface of) skin
• sebum / oil repels pathogens
• scabs form over cuts or scabs form a barrier • platelets are involved in forming clots / scab
stomach
• contains (hydrochloric) acid
• (HCl) kills bacteria
• in food or in swallowed mucus
eyes
• produce tears
• contains enzymes to kill bacteria • tears are antiseptic
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) WBCs engulf pathogens
antitoxins are produced
(antitoxins) neutralise toxins / poisons (produced by pathogen) antibodies are produced
(antibodies) help destroy pathogens
memory cells (are formed)
(memory cells give a) more rapid response if pathogen re-enters
a level 2 response should refer to body defence and the immune
How does humidity affect rate of water loss
As humidity increases water loss decreases as concentration gradient is nor as steep
With a leaky valve why is it harder for a person to exercise
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 (instead of being
pumped out) 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)
How is small intestine adapted for efficient gas exchange
projections / folds / villi provide a large surface area
walls of projections / folds / villi / capillaries are thin / one cell thick for shorter absorption / diffusion distance
(small intestine is) very long, increasing time (for absorption)
good / efficient blood supply to maintain concentration gradient
cells have many mitochondria for (aerobic) respiration for active transport
or
cells have many mitochondria for energy release for active transport
Extra information Mark
AO / Spec. Ref.
ignore small intestine has a large surface area
do not allow cilia
Why is it better to have a double circulatory system than just one loop
oxygenated and deoxygenated blood mixes
(so) less oxygen reaches the body / tissues / cells
Why is it bad if fish are in oxygen low seas
concentration gradient (of
oxygen) is shallow(er) / less steep
(therefore) less oxygen diffuses into blood / cells / gills
(so) less (aerobic) respiration occurs so less energy is released / available
or
(so more) anaerobic respiration occurs so less energy is released / available
(so) less metabolism
or
(so when) anaerobic respiration occurs, lactic acid is produced (and is toxic
Why is it bad for a fish to be used to study humans
Processes are too different for humans
Why does someone with pancreatic cancer face weight loss
reduced / no enzyme production / release (from pancreas)
food is not broken down fully or food is not digested fully
plus any one of the following routes for max 2 marks:
less glucose / sugar absorbed or less glucose / sugar passes into the blood(stream)
(so) less glucose available for respiration so more (body / stored) fat used up in metabolism / respiration
or
fewer amino acids absorbed or fewer amino acids pass into the blood(stream) (1)
(so) fewer amino acids are available for making new protein for repair / replacement (1)
or
fewer fatty acids absorbed or fewer fatty acids pass into the blood(stream) (1)
(so) fewer fatty acids available so less fat is stored in the body (1)
or
chemotherapy / radiotherapy causes nausea / loss of appetite (1)
(so) less intake of food (1)
How can MABs kill cancer
monoclonal antibody is attached to radioactive substance / toxin / drug / chemical
monoclonal antibody will (only) attach to / target (antigen on) cancer cells / tumour
(so) radioactive substance / toxin / drug / chemical will (bind to cancer cells and) stop them growing / dividing
