OCR A LEVEL BIOLOGY ACTUAL EXAM
PAPER 2026 QUESTIONS SOLUTIONS
GRADED A+
●● closed circulatory system Answer: *Blood enclosed* in blood
vessels and doesnt have direct contact with all cells.
*Heart pumps* blood under pressure, blood *returns* to the heart.
substances enter/leave blood through blood vessel walls.
Blood flow of tissues adjusted by *widening/constricting* blood vessels.
*effective transport system for multicellular mammals* - allows blood to
travel rapidly under high pressure to wherever it's needed.
●● Single closed circulatory system Answer: Blood passes through 2
sets of capillaries beforing returning to heart.
1st set of capillaries - O2 and CO2 exchanged.
,2nd set of capillaries - substances exchanged between blood and cells in
different organ systems.
Narrow capillaries so blood pressure drops before slowly returning to
the heart. This limits efficiency of exchange processes so metabolic
activity is relatively low.
●● Most animals with a closed ciruclatory system have a low metabolic
activity. Why are fish the exception? Answer: Fish have *counter-current
exchange system*.
Water with *high* concentration of O2 flow past blood with *low*
concentration of O2 at high pressure, in *opposite directions*.
This ensures that there is always a *concentration gradient maintained*.
Efficient exchange process so metabolic activity is high.
●● Double closed circulatory system. Answer: Blood completes two
circuits.
Blood pumped from heart to lungs, to pick up O2 and unload CO2 and
then returns to heart.
, Blood flows through the heart and is pumped out to travel all around the
body before returning to the heart again.
●● Open circulatory system in insect Answer: Blood fills body cavity
(*haemocel*) at a low pressure.
Blood *doesnt transport O2/CO2* but transports *food and nitrogenous
waste products and immunological cells*.
O2/CO2 transported via spiracels and trachae.
*Haemolymph* (insect blood bathes organs directly and moves slowly
through the tissue, returning to heart via collecting ducts.
●● Function of blood Answer: Transportation materials to and from cells
Transports nutrients, carries O2, waste products, hormones to their target
cells, regulates body temperature, protects against bacteria and viruses
Transports platelets to damages areas
●● Arteries Answer: Carries oxygenated blood away from heart except
the pulmonary artery which carries deoxygenated blood away from the
heart.
PAPER 2026 QUESTIONS SOLUTIONS
GRADED A+
●● closed circulatory system Answer: *Blood enclosed* in blood
vessels and doesnt have direct contact with all cells.
*Heart pumps* blood under pressure, blood *returns* to the heart.
substances enter/leave blood through blood vessel walls.
Blood flow of tissues adjusted by *widening/constricting* blood vessels.
*effective transport system for multicellular mammals* - allows blood to
travel rapidly under high pressure to wherever it's needed.
●● Single closed circulatory system Answer: Blood passes through 2
sets of capillaries beforing returning to heart.
1st set of capillaries - O2 and CO2 exchanged.
,2nd set of capillaries - substances exchanged between blood and cells in
different organ systems.
Narrow capillaries so blood pressure drops before slowly returning to
the heart. This limits efficiency of exchange processes so metabolic
activity is relatively low.
●● Most animals with a closed ciruclatory system have a low metabolic
activity. Why are fish the exception? Answer: Fish have *counter-current
exchange system*.
Water with *high* concentration of O2 flow past blood with *low*
concentration of O2 at high pressure, in *opposite directions*.
This ensures that there is always a *concentration gradient maintained*.
Efficient exchange process so metabolic activity is high.
●● Double closed circulatory system. Answer: Blood completes two
circuits.
Blood pumped from heart to lungs, to pick up O2 and unload CO2 and
then returns to heart.
, Blood flows through the heart and is pumped out to travel all around the
body before returning to the heart again.
●● Open circulatory system in insect Answer: Blood fills body cavity
(*haemocel*) at a low pressure.
Blood *doesnt transport O2/CO2* but transports *food and nitrogenous
waste products and immunological cells*.
O2/CO2 transported via spiracels and trachae.
*Haemolymph* (insect blood bathes organs directly and moves slowly
through the tissue, returning to heart via collecting ducts.
●● Function of blood Answer: Transportation materials to and from cells
Transports nutrients, carries O2, waste products, hormones to their target
cells, regulates body temperature, protects against bacteria and viruses
Transports platelets to damages areas
●● Arteries Answer: Carries oxygenated blood away from heart except
the pulmonary artery which carries deoxygenated blood away from the
heart.
