1|Page
EDEXCEL A-LEVEL BIOLOGY PAPER 1 2026
UPDATE|COMPLETE EXAM SET QUESTIONS AND
VERIFIED ANSWERS | GET IT 100% ACCURATE!!|
ALREADY PASSED A+
What is the function of the cell membrane? - ANSWER -To control what
enters and leaves the cell, acts as a barrier between the cell and its
environment.
What structural feature of the cell membrane allows substances to
enter/leave? - ANSWER -Partially permeable
What is the fluid mosaic model? - ANSWER -States that a membrane is
a fluid structure (because phospholipids are constantly moving) with a
"mosaic" of various proteins embedded in it
Describe the structure and function of phospholipids. - ANSWER -
Hydrophilic head and hydrophobic tail, arranged in a bilayer (heads face
outwards, tails face inwards). Lipid-soluble substances only allowed to
pass through.
What is the function of cholesterol in the CSM? - ANSWER -Make
phospholipids pack more closely together, restricting the movement of
the phospholipids, making the membrane less fluid/more rigid.
,2|Page
What is simple diffusion? - ANSWER -The (passive) movement of
particles from an area of high concentration to an area of low
concentration.
What is facilitated diffusion? - ANSWER -The passive movement of a
large/charged particle down its concentration gradient through a
carrier/channel protein.
What is the process of facilitated diffusion using a carrier protein? -
ANSWER -Large molecule binds to a carrier protein in membrane.
Protein changes shape.
Protein releases the large molecule on the opposite side of the
membrane.
What is the process of facilitated diffusion using a channel protein? -
ANSWER -Channel proteins form pores in membrane.
Charged particles can diffuse down their concentration gradients to the
opposite side of the membrane.
What are the factors affecting simple diffusion? - ANSWER -
Concentration gradient, thickness of exchange surface and surface area.
What are the factors affecting facilitated diffusion? - ANSWER -Number
of transport proteins and strength of gradient.
,3|Page
What is osmosis? - ANSWER -Diffusion of water through a partially
permeable membrane from an area of high water potential to an area
of lower water potential.
What are the factors affecting osmosis? - ANSWER -Water potential
gradient.
Thickness of exchange surface.
Surface area of exchange surface.
Outline a method for RP3 (investigation of osmosis using potato chips). -
ANSWER -Produce a series of dilutions from 1M sucrose solution (of a
variety of different concentrations, 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M).
Use a cork borer to cut potatoes into identically-sized chips.
Blot them dry with a paper towel and measure the mass of each using a
mass balance.
Place one chip into each of the sucrose solutions.
Put the test tubes into a water bath at 30°C for 20 minutes.
Take them out and reweigh the mass of the chips.
Calculate the %change in mass for each chip.
What is active transport? - ANSWER -The active process of moving
molecules from an area of low concentration to an area of high
concentration using ATP.
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Name one type of carrier protein and describe how it works. - ANSWER
-Co-transporters.
Bind two molecules at once.
The concentration gradient of one of the molecules is used to move the
other molecule against its own concentration gradient.
Give an example of co-transport in mammals. - ANSWER -Glucose/Na+
co-transport.
Na+ actively transported out of the ileum epithelial cells into the blood
by the Na+/K+ pump. This creates a concentration gradient, higher
concentration of Na+ in lumen than inside cell.
Na+ Defuses into the epithelial cells from the lumen Na+/glucose co-
transporter proteins.
Co-transporter carries glucose into the cell with the sodium so glucose
concentration inside the cell increases.
Glucose diffuses out of the cell, down its concentration gradient,
through a protein channel, into the blood, by facilitated diffusion.
What are the factors affecting active transport? - ANSWER -Speed of
individual carrier proteins.
Number of carrier proteins present.
Rate of respiration/availability of ATP.
3.2.1 Cell Structure - ANSWER -
EDEXCEL A-LEVEL BIOLOGY PAPER 1 2026
UPDATE|COMPLETE EXAM SET QUESTIONS AND
VERIFIED ANSWERS | GET IT 100% ACCURATE!!|
ALREADY PASSED A+
What is the function of the cell membrane? - ANSWER -To control what
enters and leaves the cell, acts as a barrier between the cell and its
environment.
What structural feature of the cell membrane allows substances to
enter/leave? - ANSWER -Partially permeable
What is the fluid mosaic model? - ANSWER -States that a membrane is
a fluid structure (because phospholipids are constantly moving) with a
"mosaic" of various proteins embedded in it
Describe the structure and function of phospholipids. - ANSWER -
Hydrophilic head and hydrophobic tail, arranged in a bilayer (heads face
outwards, tails face inwards). Lipid-soluble substances only allowed to
pass through.
What is the function of cholesterol in the CSM? - ANSWER -Make
phospholipids pack more closely together, restricting the movement of
the phospholipids, making the membrane less fluid/more rigid.
,2|Page
What is simple diffusion? - ANSWER -The (passive) movement of
particles from an area of high concentration to an area of low
concentration.
What is facilitated diffusion? - ANSWER -The passive movement of a
large/charged particle down its concentration gradient through a
carrier/channel protein.
What is the process of facilitated diffusion using a carrier protein? -
ANSWER -Large molecule binds to a carrier protein in membrane.
Protein changes shape.
Protein releases the large molecule on the opposite side of the
membrane.
What is the process of facilitated diffusion using a channel protein? -
ANSWER -Channel proteins form pores in membrane.
Charged particles can diffuse down their concentration gradients to the
opposite side of the membrane.
What are the factors affecting simple diffusion? - ANSWER -
Concentration gradient, thickness of exchange surface and surface area.
What are the factors affecting facilitated diffusion? - ANSWER -Number
of transport proteins and strength of gradient.
,3|Page
What is osmosis? - ANSWER -Diffusion of water through a partially
permeable membrane from an area of high water potential to an area
of lower water potential.
What are the factors affecting osmosis? - ANSWER -Water potential
gradient.
Thickness of exchange surface.
Surface area of exchange surface.
Outline a method for RP3 (investigation of osmosis using potato chips). -
ANSWER -Produce a series of dilutions from 1M sucrose solution (of a
variety of different concentrations, 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M).
Use a cork borer to cut potatoes into identically-sized chips.
Blot them dry with a paper towel and measure the mass of each using a
mass balance.
Place one chip into each of the sucrose solutions.
Put the test tubes into a water bath at 30°C for 20 minutes.
Take them out and reweigh the mass of the chips.
Calculate the %change in mass for each chip.
What is active transport? - ANSWER -The active process of moving
molecules from an area of low concentration to an area of high
concentration using ATP.
, 4|Page
Name one type of carrier protein and describe how it works. - ANSWER
-Co-transporters.
Bind two molecules at once.
The concentration gradient of one of the molecules is used to move the
other molecule against its own concentration gradient.
Give an example of co-transport in mammals. - ANSWER -Glucose/Na+
co-transport.
Na+ actively transported out of the ileum epithelial cells into the blood
by the Na+/K+ pump. This creates a concentration gradient, higher
concentration of Na+ in lumen than inside cell.
Na+ Defuses into the epithelial cells from the lumen Na+/glucose co-
transporter proteins.
Co-transporter carries glucose into the cell with the sodium so glucose
concentration inside the cell increases.
Glucose diffuses out of the cell, down its concentration gradient,
through a protein channel, into the blood, by facilitated diffusion.
What are the factors affecting active transport? - ANSWER -Speed of
individual carrier proteins.
Number of carrier proteins present.
Rate of respiration/availability of ATP.
3.2.1 Cell Structure - ANSWER -
