2025_AQA: AS BIOLOGY
Paper 1 (Merged Question
paper and marking
scheme) Monday 13 May
2025
Microscopes - Answer--Light microscope: cheap, can see cell outline
Electron microscope: finer details including organelles due to greater resolving power
and higher definition
micrometer - Answer--'μm'
Equal to 1x10^-6 meters
Or 1000th (1x10^-3) of a mm
Animal and plant cell organelles - Answer--Cell membrane- semi permeable: controls
what enters and exits
Nucleus- DNA
Mitochondria- respiration
Ribosomes- protein synthesis
Cytoplasm
Embryo Clones - Answer--Make clone of an embryo of a person, extract stem cells
Done so they won't be rejected
Diffusion - Answer--Movement of particles down the concentration gradient
Passive- no energy
Increase: difference in concentrations, surface area, temperature
, Osmosis - Answer--Diffusion of water through a semi-permeable membrane to balance
concentration of solutions
Must be water to move because larger particles can't fit through
Active transport - Answer--Movement of particles through a membrane via carrier
proteins
Requires energy, can go against concentration gradient
Osmosis practical - Answer--Weigh identical vegetable pieces and place in varying
concentrations of sugar solutions
After set time, remove from solution, dry to remove excess liquid, reweigh
Calculate change in mass
Plot graph
At 0% change in mass, the concentrations were equal
Organisation of human systems - Answer--Cell, tissue, organ, organ system
DS: Mouth - Answer--Teeth break down food mechanically
Saliva contains amylase
DS: Stomach - Answer--Churns food together with hydrochloric acid and enzymes
DS: Liver - Answer--Produces blue- stored in gall bladder before going to small intestine
Bile emulsifies lipids into small droplets, increasing surface area for better digestion
DS: Pancreas - Answer--Secretes amylase which breaks down starch into glucose in
the small intestine
DS: Small intestine - Answer--Nutrients absorbed by villi
However starch is too large
DS: Large intestine - Answer--Water absorbed
Enzymes - Answer--Special proteins that act as biological catalysts, breaking down
molecules into shorter ones (polymers to monomers)
Specific- only breaking down molecules that fit its active site (lock and key model)
Enzyme Denaturation - Answer--Temperature increases enzyme activity until denature
(when the active site changes shape)
Same is true for pH
Optimum= the condition for maximum activity
Digestive enzymes - Answer--Carbohydrases break down carbohydrates into simple
sugars
Proteases break down proteins into amino acids
Lipases break down lipids into glycerol and fatty acids
Paper 1 (Merged Question
paper and marking
scheme) Monday 13 May
2025
Microscopes - Answer--Light microscope: cheap, can see cell outline
Electron microscope: finer details including organelles due to greater resolving power
and higher definition
micrometer - Answer--'μm'
Equal to 1x10^-6 meters
Or 1000th (1x10^-3) of a mm
Animal and plant cell organelles - Answer--Cell membrane- semi permeable: controls
what enters and exits
Nucleus- DNA
Mitochondria- respiration
Ribosomes- protein synthesis
Cytoplasm
Embryo Clones - Answer--Make clone of an embryo of a person, extract stem cells
Done so they won't be rejected
Diffusion - Answer--Movement of particles down the concentration gradient
Passive- no energy
Increase: difference in concentrations, surface area, temperature
, Osmosis - Answer--Diffusion of water through a semi-permeable membrane to balance
concentration of solutions
Must be water to move because larger particles can't fit through
Active transport - Answer--Movement of particles through a membrane via carrier
proteins
Requires energy, can go against concentration gradient
Osmosis practical - Answer--Weigh identical vegetable pieces and place in varying
concentrations of sugar solutions
After set time, remove from solution, dry to remove excess liquid, reweigh
Calculate change in mass
Plot graph
At 0% change in mass, the concentrations were equal
Organisation of human systems - Answer--Cell, tissue, organ, organ system
DS: Mouth - Answer--Teeth break down food mechanically
Saliva contains amylase
DS: Stomach - Answer--Churns food together with hydrochloric acid and enzymes
DS: Liver - Answer--Produces blue- stored in gall bladder before going to small intestine
Bile emulsifies lipids into small droplets, increasing surface area for better digestion
DS: Pancreas - Answer--Secretes amylase which breaks down starch into glucose in
the small intestine
DS: Small intestine - Answer--Nutrients absorbed by villi
However starch is too large
DS: Large intestine - Answer--Water absorbed
Enzymes - Answer--Special proteins that act as biological catalysts, breaking down
molecules into shorter ones (polymers to monomers)
Specific- only breaking down molecules that fit its active site (lock and key model)
Enzyme Denaturation - Answer--Temperature increases enzyme activity until denature
(when the active site changes shape)
Same is true for pH
Optimum= the condition for maximum activity
Digestive enzymes - Answer--Carbohydrases break down carbohydrates into simple
sugars
Proteases break down proteins into amino acids
Lipases break down lipids into glycerol and fatty acids
