Pearson Edexcel GCSE In Combined Science
(1 SC0) Paper 1CH Mark Scheme Summer
2025
What are adaptations of desert plants to help them adapt to their environment -
answersfewer stomata in plants that have dry soil because stomata allow the loss of
water vapour- fewer stomata means less water loss
more stomata in wet soils so the plants can lose more water through stomata
Animal cell sub cellular structures - answersNucleus, cytoplasm, cell membrane,
mitochondria, ribosomes
Function of nucleus - answersControls cells activities; contains the cells DNA
Specialised cells - answersCells that are adapted to carry out a particular function
Function of Mitochondria - answersSite of aerobic respiration; provides energy (ATP)
Function of Ribosomes - answersprotein synthesis
Function of Cytoplasm - answersWhere chemical reactions take place
Function of cell membrane - answersControls what enters and exits the cell
Name 3 subcellular structures of plant cells that are not in animal cells -
answersVacuole
Cell wall
Chloroplasts
Function of Vacuole - answersContains cell sap to help support the cell/ keep it turgid
Function of Chloroplasts - answerscontains chlorophyll, site of photosynthesis
Function of Cell wall - answersContains cellulose and provides protection and support
for a plant cell
Name the subcellular structures of a bacteria cell - answersPlasmid, Chromosomal
DNA, Ribosomes, Cell membrane, Capsule sometimes has a cell wall too
Formula for magnification - answersMagnification = image size / real size
What equipment is required for a Practical to observe an onion cell under a microscope
- answersStain, Cover slip, Tweezers, Slide, Onion cell.
,3 differences between Electron and Light microscopes - answers-resolution
-magnification
- beam of light/ beam of electrons
What are 2 adaptations of a sperm cell to help its function - answersAcrosome: contains
enzymes to allow breaking of the barrier that prevents the sperm cell from fertilising the
cell
What are 2 adaptations of an egg cell - answersCytoplasm with yolk- the yolk acts as a
food store for potential life
Lined with cilia epithelial cells
What is an enzyme - answersBiological catalyst speeds up reactions by lowering
activation energy
Factors that affect enzyme activity - answerspH, temperature, and concentration of
enzyme or substrate
Enzyme activity process - answersComplementary substrate binds to enzyme's specific
active site
Forms E-S Complex
Breaks substrate down and completes reaction.
How can increasing temperature, pH or concentration affect enzyme activity - answersIt
will increase enzyme activity until it reaches its optimum state of pH, temp or
concentration and after its optimum- it will decline and denature due to the change of
active site
How does the change of active site affect enzyme activity - answersChange of active
site means that its complementary substrate will be unable to bind to its specific active
site and so no E-S complex will form.
Formula for rate of reaction - answersAmount of reactant used or product formed / time
What do carbohydrates break down to form and what enzyme can break it down -
answersSimple sugars and Carbohydrase
What do proteins break down to and what enzyme can break it down - answersAmino
acids and Protease
What do lipids break down to and what enzyme can break it down - answers1 glycerol
molecule and 3 fatty acids and Lipase
Diffusion - answersMovement of molecules from an area of higher concentration to an
area of lower concentration.
,Osmosis - answersMovement of water from an area of higher water concentration to an
area of lower water concentration through a selectively permeable membrane
Active Transport - answersthe movement of ions or molecules across a cell membrane
from a low concentration into an area of higher concentration requiring energy.
milli - answers10^-3
micro - answers10^-6
nano - answers10^-9
pico - answers10^-12
Describe/ define photosynthesis - answersendothermic reaction that uses light energy
to react carbon dioxide and water to produce glucose and oxygen
factors that affect rate of photosynthesis - answerslight intensity, carbon dioxide
concentration and temperature
Explain the effects of all 3 factors on the rate of photosynthesis - answerstemp: rate of
photosynthesis increases as temperature increases however, once it reaches its
optimum temp- it will decline/decrease gradually
CO2 conc- increases rate of photosynthesis as co2 increases until it reaches its
maximum/optimum and plateaus
light intensity- increases rate of photosynthesis as light intensity increases until it
reaches its maximum/optimum and plateaus
2 adaptations of root hair cells - answerslarge surface area and thin cell walls to allow
water to pass through
Xylem - answersTransports water
Phloem - answersThe vascular tissue through which food/sugars moves in some plants
How does Xylem transport water? - answers1. tension- caused by water trying to go up
xylem
2. cohesion- upwards force caused by one molecule of water going up the column
3. adhesion- hydrogen bonds ensures a continuous water stream for transpiration
Transpiration - answersEvaporation of water from the leaves of a plant
Translocation - answersthe movement of sugars from the leaves to the rest of the plant
through the phloem
, mechanism of translocation - answers1) Transfer of sucrose into sieve elements from
photosynthesising tissue (source cell->companion cell->sieve tube elements)
2) Mass flow of sucrose through sieve tube elements
3) Transfer of sucrose from the sieve tube elements into storage or other sink cells
(companion cells-> sink/ other cells)
environmental factors affecting transpiration - answerstemperature , light intensity and
air movement
Adaptations of alveoli - answersThin walls,
Large surface area,
Lots of capillaries for a good blood supply
Adaptations of red blood cells - answers- biconcave shape to give a large surface area
for absorbing oxygen
- no nucleus so they can carry more oxygen
Adaptation of white blood cells - answersenlarged nucleus
flexible shape to adapt to different diseases and engulf them.
function of platelets - answersblood clotting- no nucleus
plasma - answersliquid that carries the components of blood
What grade is Faatima going to get for GCSE combined science ? - answers8!
adaptations of arteries - answersThick layer of muscle in walls and elastic fibres to
withstand high pressure pressure.
Adaptations of veins - answersThinner walls, wide lumen and valves to prevent
backflow of blood.
Capillaries - answersone cell thick and permeable walls so substances can pass
through
Describe where hormones are produced (endocrine glands) - answersPituitary gland-
the master gland, secretes hormones into the blood or act on other glands to stimulate
them to produce different hormones
Pancreas- secretes insulin, controls blood glucose levels
Thyroid- secretes thyroxine, controls metabolic rate, temperature and heart rate
Adrenal gland- secretes adrenaline, involved in fight or flight response response
Ovary- secretes oestrogen, involved in the menstrual cycle and development of female
sexual characteristics.
Testes- secretes testosterone, involved in sperm production and development of
secondary sexual male characteristics
(1 SC0) Paper 1CH Mark Scheme Summer
2025
What are adaptations of desert plants to help them adapt to their environment -
answersfewer stomata in plants that have dry soil because stomata allow the loss of
water vapour- fewer stomata means less water loss
more stomata in wet soils so the plants can lose more water through stomata
Animal cell sub cellular structures - answersNucleus, cytoplasm, cell membrane,
mitochondria, ribosomes
Function of nucleus - answersControls cells activities; contains the cells DNA
Specialised cells - answersCells that are adapted to carry out a particular function
Function of Mitochondria - answersSite of aerobic respiration; provides energy (ATP)
Function of Ribosomes - answersprotein synthesis
Function of Cytoplasm - answersWhere chemical reactions take place
Function of cell membrane - answersControls what enters and exits the cell
Name 3 subcellular structures of plant cells that are not in animal cells -
answersVacuole
Cell wall
Chloroplasts
Function of Vacuole - answersContains cell sap to help support the cell/ keep it turgid
Function of Chloroplasts - answerscontains chlorophyll, site of photosynthesis
Function of Cell wall - answersContains cellulose and provides protection and support
for a plant cell
Name the subcellular structures of a bacteria cell - answersPlasmid, Chromosomal
DNA, Ribosomes, Cell membrane, Capsule sometimes has a cell wall too
Formula for magnification - answersMagnification = image size / real size
What equipment is required for a Practical to observe an onion cell under a microscope
- answersStain, Cover slip, Tweezers, Slide, Onion cell.
,3 differences between Electron and Light microscopes - answers-resolution
-magnification
- beam of light/ beam of electrons
What are 2 adaptations of a sperm cell to help its function - answersAcrosome: contains
enzymes to allow breaking of the barrier that prevents the sperm cell from fertilising the
cell
What are 2 adaptations of an egg cell - answersCytoplasm with yolk- the yolk acts as a
food store for potential life
Lined with cilia epithelial cells
What is an enzyme - answersBiological catalyst speeds up reactions by lowering
activation energy
Factors that affect enzyme activity - answerspH, temperature, and concentration of
enzyme or substrate
Enzyme activity process - answersComplementary substrate binds to enzyme's specific
active site
Forms E-S Complex
Breaks substrate down and completes reaction.
How can increasing temperature, pH or concentration affect enzyme activity - answersIt
will increase enzyme activity until it reaches its optimum state of pH, temp or
concentration and after its optimum- it will decline and denature due to the change of
active site
How does the change of active site affect enzyme activity - answersChange of active
site means that its complementary substrate will be unable to bind to its specific active
site and so no E-S complex will form.
Formula for rate of reaction - answersAmount of reactant used or product formed / time
What do carbohydrates break down to form and what enzyme can break it down -
answersSimple sugars and Carbohydrase
What do proteins break down to and what enzyme can break it down - answersAmino
acids and Protease
What do lipids break down to and what enzyme can break it down - answers1 glycerol
molecule and 3 fatty acids and Lipase
Diffusion - answersMovement of molecules from an area of higher concentration to an
area of lower concentration.
,Osmosis - answersMovement of water from an area of higher water concentration to an
area of lower water concentration through a selectively permeable membrane
Active Transport - answersthe movement of ions or molecules across a cell membrane
from a low concentration into an area of higher concentration requiring energy.
milli - answers10^-3
micro - answers10^-6
nano - answers10^-9
pico - answers10^-12
Describe/ define photosynthesis - answersendothermic reaction that uses light energy
to react carbon dioxide and water to produce glucose and oxygen
factors that affect rate of photosynthesis - answerslight intensity, carbon dioxide
concentration and temperature
Explain the effects of all 3 factors on the rate of photosynthesis - answerstemp: rate of
photosynthesis increases as temperature increases however, once it reaches its
optimum temp- it will decline/decrease gradually
CO2 conc- increases rate of photosynthesis as co2 increases until it reaches its
maximum/optimum and plateaus
light intensity- increases rate of photosynthesis as light intensity increases until it
reaches its maximum/optimum and plateaus
2 adaptations of root hair cells - answerslarge surface area and thin cell walls to allow
water to pass through
Xylem - answersTransports water
Phloem - answersThe vascular tissue through which food/sugars moves in some plants
How does Xylem transport water? - answers1. tension- caused by water trying to go up
xylem
2. cohesion- upwards force caused by one molecule of water going up the column
3. adhesion- hydrogen bonds ensures a continuous water stream for transpiration
Transpiration - answersEvaporation of water from the leaves of a plant
Translocation - answersthe movement of sugars from the leaves to the rest of the plant
through the phloem
, mechanism of translocation - answers1) Transfer of sucrose into sieve elements from
photosynthesising tissue (source cell->companion cell->sieve tube elements)
2) Mass flow of sucrose through sieve tube elements
3) Transfer of sucrose from the sieve tube elements into storage or other sink cells
(companion cells-> sink/ other cells)
environmental factors affecting transpiration - answerstemperature , light intensity and
air movement
Adaptations of alveoli - answersThin walls,
Large surface area,
Lots of capillaries for a good blood supply
Adaptations of red blood cells - answers- biconcave shape to give a large surface area
for absorbing oxygen
- no nucleus so they can carry more oxygen
Adaptation of white blood cells - answersenlarged nucleus
flexible shape to adapt to different diseases and engulf them.
function of platelets - answersblood clotting- no nucleus
plasma - answersliquid that carries the components of blood
What grade is Faatima going to get for GCSE combined science ? - answers8!
adaptations of arteries - answersThick layer of muscle in walls and elastic fibres to
withstand high pressure pressure.
Adaptations of veins - answersThinner walls, wide lumen and valves to prevent
backflow of blood.
Capillaries - answersone cell thick and permeable walls so substances can pass
through
Describe where hormones are produced (endocrine glands) - answersPituitary gland-
the master gland, secretes hormones into the blood or act on other glands to stimulate
them to produce different hormones
Pancreas- secretes insulin, controls blood glucose levels
Thyroid- secretes thyroxine, controls metabolic rate, temperature and heart rate
Adrenal gland- secretes adrenaline, involved in fight or flight response response
Ovary- secretes oestrogen, involved in the menstrual cycle and development of female
sexual characteristics.
Testes- secretes testosterone, involved in sperm production and development of
secondary sexual male characteristics
