AQA A Level Biology Paper 1 Questions And Correct
Answers
Water removed from the reactants joining two molecules together forming a
chemical bond
Condensation
The addition of water to the reactants to break a chemical bond between 2
molecules
Hydrolysis
1. Add Benedict's reagent. 2. Heat the solution in a water bath for 5 minutes at
95 degrees Celsius. 3. Change from blue to brick red as CuO formed
Test for Reducing Sugars (3)
Smaller units from which larger molecules are made
Monomer
1. Add 2cm³ of food sample then add 2cm³ of dilute HCl and heat.
2. Add 2cm³ of NaHCO3 then do test for reducing sugars.
Non-Reducing Sugars (2)
Add drops of iodine to starch solution. Colour change to blue-black
Test for Starch (1)
1. Mix Test solution with ethanol.
2. Shake for 1 minute then add water.
3. Cloudy white emulsion
Test for Lipids (3)
1. Obtain equal volumes of test solution and NaOH then add a few drops of
biuret solution (dilute copper (II) sulphate solution).
2. Colour change to mauve/purple
Test for Proteins (2)
1. Very high resolution.
2. Needs thin and dead specimen.
3. Artefacts can occur (remnant left on object during prep, such as air bubbles)
4. Uses magnets to focus on specimen
,5. Uses electrons fired at sample.
6. Is not in colour
Transmission Electron Microscope (5)
1. Inhibitor is similar in shape to substrate so it impermanently binds to the
active site.
2. Prevents ESC from forming, slowing rate
Competitive inhibition (2)
1. Molecule will bind to allosteric site.
2. Binding causes a change in active site.
3. Permanently preventing further ESC.
Non-competitive inhibition (3)
1. DNA helicase breaks the hydrogen bonds between the base pairs
2. 2 single strands formed as the double helix "unzips".
3. Free DNA nucleotides in the nucleoplasm bond to the complementary bases
on the strand.
4. DNA polymerase forms phosphodiester bonds between adjacent DNA
nucleotides via condensation reaction with the hydrolysis of ATP, forming the
phosphate backbone
DNA Replication: Semiconservative (4)
1. ATP stores or releases only a small amount of energy at a time, so no
energy is wasted as heat.
2. Small and soluble so easily transported
3. Easily broken down, so energy is released instantaneously
4. Can be quickly re-made
5. Can make other molecules more reactive via phosphorylation
6. ATP can't pass out of cell, so the cell always has an immediate supply of
energy.
Describe 6 properties of ATP that make it a good energy source. (6)
Prevents the cell from drying out. Allows bacteria to stick to each other
Slime capsule (2)
Used for attachment of a cell to a surface
Fimbria
Involved in bacterial conjugation
Pilli
,Invagination of cell membrane. Site of cell respiration (prokaryotes)
Mesosome
The ability to distinguish two points apart
Resolution
1. Lower resolution than TEM
2. 3D image
3. Does not require thin samples
Scanning Electron Microscope
The mass of organelles at the bottom of the test tube after centrifugation.
Pellet
Cold. Low temperature slows enzyme activity, minimising self digestion by
reducing metabolic rate. Isotonic. Salt and sugar concentration kept the same,
minimising organelle size change due to osmosis. Buffered. Minimum changes
in pH, so prevents enzymes in organelles denaturing.
Solution Required for cell fractionation (6 Marks)
1. Homogenisation. Breaking up cells by blending the sample to create a
homogenate.
2. Filtering. Filtering the large, unwanted sil, producing the filtrate.
3. Ultracentrifugation. Spin in a centrifuge so components separate out by
weight. Heavier near the bottom of the tube.
4. Supernatant is removed and spun again at higher speed.
Separation of Organelles From The Cells (4)
The solution not including the pellet at the bottom of the test tube after
centrifugation.
Supernatant
1. Cell wall forms, dividing the two genetically identical daughter cells.
2. Same circular DNA.
Binary Fission 3
Nuclei, Chloroplasts, Mitochondria, Lysosomes, Endoplasmic Reticulum,
Ribosomes
Order of Organelles
(Pass me a taco chief)
Mitosis acronym
Cell grows and carrys out its normal function
, Interphase
Cells grow to normal size. Organelles replicate and genes are expressed to
make proteins needed.
Interphase G1
DNA and histones replicated.
Interphase S
Spindle fibres are made
Interphase G2
1. DNA winds up making chromosones from chromatin.
2. Centrioles appear at opposite poles of the cell. 3. Nucleolus disappears
Prophase (3)
1. Nuclear envelope disappears.
2. Chromosomes align along the equator of the cell.
3. Spindle fibres connect centrioles to chromosomes
Metaphase (3)
1. Spindle fibres contract pulling daughter chromosomes to opposite poles of
the cell.
Anaphase (1)
1. Spindle fibres disperse.
2. Nuclear envelope forms.
3. Chromatids uncoil to chromatin
Telophase (3)
1. Cytoplasm constricts separating the cells into two.
2. Membrane forms creating two new genetically identical daughter cells.
Cytokinesis (2)
number of cells in mitosis/total number of cells
Mitotic index
1. Circular DNA replicates and both copies attach to the cell membrane.
2. Plasmids also replicate.
Binary fission 1 (2)
Cell membrane grows between the two DNA molecules and pinches them
inwards dividing the cell into 2.
Binary Fission 2 (1)
Answers
Water removed from the reactants joining two molecules together forming a
chemical bond
Condensation
The addition of water to the reactants to break a chemical bond between 2
molecules
Hydrolysis
1. Add Benedict's reagent. 2. Heat the solution in a water bath for 5 minutes at
95 degrees Celsius. 3. Change from blue to brick red as CuO formed
Test for Reducing Sugars (3)
Smaller units from which larger molecules are made
Monomer
1. Add 2cm³ of food sample then add 2cm³ of dilute HCl and heat.
2. Add 2cm³ of NaHCO3 then do test for reducing sugars.
Non-Reducing Sugars (2)
Add drops of iodine to starch solution. Colour change to blue-black
Test for Starch (1)
1. Mix Test solution with ethanol.
2. Shake for 1 minute then add water.
3. Cloudy white emulsion
Test for Lipids (3)
1. Obtain equal volumes of test solution and NaOH then add a few drops of
biuret solution (dilute copper (II) sulphate solution).
2. Colour change to mauve/purple
Test for Proteins (2)
1. Very high resolution.
2. Needs thin and dead specimen.
3. Artefacts can occur (remnant left on object during prep, such as air bubbles)
4. Uses magnets to focus on specimen
,5. Uses electrons fired at sample.
6. Is not in colour
Transmission Electron Microscope (5)
1. Inhibitor is similar in shape to substrate so it impermanently binds to the
active site.
2. Prevents ESC from forming, slowing rate
Competitive inhibition (2)
1. Molecule will bind to allosteric site.
2. Binding causes a change in active site.
3. Permanently preventing further ESC.
Non-competitive inhibition (3)
1. DNA helicase breaks the hydrogen bonds between the base pairs
2. 2 single strands formed as the double helix "unzips".
3. Free DNA nucleotides in the nucleoplasm bond to the complementary bases
on the strand.
4. DNA polymerase forms phosphodiester bonds between adjacent DNA
nucleotides via condensation reaction with the hydrolysis of ATP, forming the
phosphate backbone
DNA Replication: Semiconservative (4)
1. ATP stores or releases only a small amount of energy at a time, so no
energy is wasted as heat.
2. Small and soluble so easily transported
3. Easily broken down, so energy is released instantaneously
4. Can be quickly re-made
5. Can make other molecules more reactive via phosphorylation
6. ATP can't pass out of cell, so the cell always has an immediate supply of
energy.
Describe 6 properties of ATP that make it a good energy source. (6)
Prevents the cell from drying out. Allows bacteria to stick to each other
Slime capsule (2)
Used for attachment of a cell to a surface
Fimbria
Involved in bacterial conjugation
Pilli
,Invagination of cell membrane. Site of cell respiration (prokaryotes)
Mesosome
The ability to distinguish two points apart
Resolution
1. Lower resolution than TEM
2. 3D image
3. Does not require thin samples
Scanning Electron Microscope
The mass of organelles at the bottom of the test tube after centrifugation.
Pellet
Cold. Low temperature slows enzyme activity, minimising self digestion by
reducing metabolic rate. Isotonic. Salt and sugar concentration kept the same,
minimising organelle size change due to osmosis. Buffered. Minimum changes
in pH, so prevents enzymes in organelles denaturing.
Solution Required for cell fractionation (6 Marks)
1. Homogenisation. Breaking up cells by blending the sample to create a
homogenate.
2. Filtering. Filtering the large, unwanted sil, producing the filtrate.
3. Ultracentrifugation. Spin in a centrifuge so components separate out by
weight. Heavier near the bottom of the tube.
4. Supernatant is removed and spun again at higher speed.
Separation of Organelles From The Cells (4)
The solution not including the pellet at the bottom of the test tube after
centrifugation.
Supernatant
1. Cell wall forms, dividing the two genetically identical daughter cells.
2. Same circular DNA.
Binary Fission 3
Nuclei, Chloroplasts, Mitochondria, Lysosomes, Endoplasmic Reticulum,
Ribosomes
Order of Organelles
(Pass me a taco chief)
Mitosis acronym
Cell grows and carrys out its normal function
, Interphase
Cells grow to normal size. Organelles replicate and genes are expressed to
make proteins needed.
Interphase G1
DNA and histones replicated.
Interphase S
Spindle fibres are made
Interphase G2
1. DNA winds up making chromosones from chromatin.
2. Centrioles appear at opposite poles of the cell. 3. Nucleolus disappears
Prophase (3)
1. Nuclear envelope disappears.
2. Chromosomes align along the equator of the cell.
3. Spindle fibres connect centrioles to chromosomes
Metaphase (3)
1. Spindle fibres contract pulling daughter chromosomes to opposite poles of
the cell.
Anaphase (1)
1. Spindle fibres disperse.
2. Nuclear envelope forms.
3. Chromatids uncoil to chromatin
Telophase (3)
1. Cytoplasm constricts separating the cells into two.
2. Membrane forms creating two new genetically identical daughter cells.
Cytokinesis (2)
number of cells in mitosis/total number of cells
Mitotic index
1. Circular DNA replicates and both copies attach to the cell membrane.
2. Plasmids also replicate.
Binary fission 1 (2)
Cell membrane grows between the two DNA molecules and pinches them
inwards dividing the cell into 2.
Binary Fission 2 (1)
