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AQA Biology A-Level: Exchange Questions and Answers May 2024 Exam
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AQA Biology A-Level: Exchange Questions and Answers May 2024 Exam
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AQA Biology A-Level: ExchangeQuestions and Answers May 2024 Exam
what affects the amount of material that is exchanged in an
organism? - Answer>> size and metabolic rate- higher
metabolic rate= more materials exchanged
name 4 things that need to be exchanged between an organism
and their environment. - Answer>> - respiratory gases
- nutrients
- excretory products
- heat
how do you calculate the surface area to volume ratio? -
Answer>>
how does gas exchange occur in a single-celled organism? -
Answer>> they are small organisms so have a large surface
area to volume ratio and therefore can exchange substances
through diffusion across their body surface
how are respiratory gases moved in and out of an insect along a
diffusion gradient? - Answer>> during cell respiration, O2
concentration at the end of tracheoles decreases so O2 from the
atmosphere is drawn in by diffusion along a concentration
gradient. the CO2 produced goes the opposite way
how are respiratory gases moved in and out of an insect using
water that fills the ends of the tracheoles? - Answer>> during
periods of high activity, muscles carry out anaerobic respiration
which produces lactate, a soluble liquid that lowers water potential
of muscle cells. this causes water to move from tracheoles to the
, cells by osmosis. this causes water in tracheoles to decrease in
volume which draws air into them through a diffusion gradient
what are spiracles and how do they work? - Answer>> they are
tiny pores on the body surface of an insect that open and close
using a valve. they can allow water vapour to evaporate from
them and tend to stay shut to avoid water loss.
explain how the tracheal system limits the size of insects -
Answer>> it relies on diffusion to bring oxygen to the respiring
tissues. if insects were large it would take too long for oxygen to
reach all the tissues quickly enough so the insect would die
why is there a conflict in insects between gas exchange and
conserving water? - Answer>> gas exchange requires a thin,
permeable surface with a large area whereas conserving water
requires thick, waterproof surfaces with a small area
how does countercurrent flow work? - Answer>> blood that is
already well-loaded with oxygen will meet water that has its
maximum concentration of oxygen. this causes a diffusion of
oxygen from the water to the blood
blood with little oxygen in it will meet water that has had most of
its oxygen removed, this means diffusion of oxygen from water to
blood will take place.
how much available oxygen is absorbed using countercurrent
flow? - Answer>> 80%
how much available oxygen would be absorbed if the flow of
blood and water was parallel? - Answer>> 50%
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