GCSE BIOLOGY HIGHER TIER PAPER 1H
STRUCTURED PRACTICE QUESTIONS AND
ANSWERS 2026
◉ what are the control variables of the light and photosynthesis
experiment Answer: number of algal balls
temperature
volume of indicator
brightness of bulb
size of bottle
same species of algae
◉ in the light and photosynthesis experiment, why does the
indicator change with increasing distance from the light source
Answer: it is yellow in more acidic solutions
it is purple in more alkali solutions
carbon dioxide is an acidic gas
the bottle closest to the light will turn purple as more
photosynthesis will occur and more carbon dioxide will be removed
the bottle furthest away will be more yellow as less carbon dioxide
will have been used due to less photosynthesis occurring
,◉ when using pondweed to invstigate the effect of light intensity on
photosynthesis, why would counting the number of bubbles not be
the most accurate method? Answer: the bubbles are of different
sizes
there is also respiration occurring at the same time and so oxygen
produced in photosynthesis is being used up
respiration also releases carbon dioxide. there is no guarantee that
the amount of carbon dioxide produced is equal to that absorbed in
photosynthesis, so counting the bubbles isnt entirely accurate
◉ what do we expect the results of the light and photosynthesis
experiment to be Answer: bottles closest to the light source will have
the greatest amount of photosynthesis occurring, and therefore the
colour will change to purple.
moving away from the light source, there will be less colour change
to purple as less carbon dioxide will have been used in
photosynthesis due to a light being the limiting factor
◉ Explain the inverse square law. Answer: 1/distance²
as the distance from the light increases, the light intensity decreases
by the inverse of the square of the distance.
for example, if the intensute is doubled, the intensity will be 1/2²
, ◉ Explain how the structure of the root hair cells is adapted to
absorb water and mineral ions Answer: root hair cells have a large
surface area to allow a greater surface for absorption of mineral ions
the hair cells also have thin walls to provide a short diffusion
pathway
they have large vacuoles to maintain osmotic pressure
their long structure allows them to anchor the plant onto the ground
◉ How are phloem adapted to their function? Answer: phloem
contains sieve tube elements which have very little cytoplasm so
that there is a lot of space to transport sucrose and other nutrients
it contains companion cells which have lots of mitochondria. these
supply energy from respiration for active transport of sucrose into
and out of sieve tube elements
sucrose is translocated around the plant in the phloem sieve tube
◉ How are xylem adapted to their function? Answer: xylem vessels
are dead cells which have no cytoplasm of cell contents. this means
there is more space for water containing mineral ions to move
through
holes called pits in their walls to allow water and mineral ions to
move out
STRUCTURED PRACTICE QUESTIONS AND
ANSWERS 2026
◉ what are the control variables of the light and photosynthesis
experiment Answer: number of algal balls
temperature
volume of indicator
brightness of bulb
size of bottle
same species of algae
◉ in the light and photosynthesis experiment, why does the
indicator change with increasing distance from the light source
Answer: it is yellow in more acidic solutions
it is purple in more alkali solutions
carbon dioxide is an acidic gas
the bottle closest to the light will turn purple as more
photosynthesis will occur and more carbon dioxide will be removed
the bottle furthest away will be more yellow as less carbon dioxide
will have been used due to less photosynthesis occurring
,◉ when using pondweed to invstigate the effect of light intensity on
photosynthesis, why would counting the number of bubbles not be
the most accurate method? Answer: the bubbles are of different
sizes
there is also respiration occurring at the same time and so oxygen
produced in photosynthesis is being used up
respiration also releases carbon dioxide. there is no guarantee that
the amount of carbon dioxide produced is equal to that absorbed in
photosynthesis, so counting the bubbles isnt entirely accurate
◉ what do we expect the results of the light and photosynthesis
experiment to be Answer: bottles closest to the light source will have
the greatest amount of photosynthesis occurring, and therefore the
colour will change to purple.
moving away from the light source, there will be less colour change
to purple as less carbon dioxide will have been used in
photosynthesis due to a light being the limiting factor
◉ Explain the inverse square law. Answer: 1/distance²
as the distance from the light increases, the light intensity decreases
by the inverse of the square of the distance.
for example, if the intensute is doubled, the intensity will be 1/2²
, ◉ Explain how the structure of the root hair cells is adapted to
absorb water and mineral ions Answer: root hair cells have a large
surface area to allow a greater surface for absorption of mineral ions
the hair cells also have thin walls to provide a short diffusion
pathway
they have large vacuoles to maintain osmotic pressure
their long structure allows them to anchor the plant onto the ground
◉ How are phloem adapted to their function? Answer: phloem
contains sieve tube elements which have very little cytoplasm so
that there is a lot of space to transport sucrose and other nutrients
it contains companion cells which have lots of mitochondria. these
supply energy from respiration for active transport of sucrose into
and out of sieve tube elements
sucrose is translocated around the plant in the phloem sieve tube
◉ How are xylem adapted to their function? Answer: xylem vessels
are dead cells which have no cytoplasm of cell contents. this means
there is more space for water containing mineral ions to move
through
holes called pits in their walls to allow water and mineral ions to
move out
