Biological Molecules | AQA A-Level Biology (7402)

Biological Molecules

272 questions
22 subtopics
Paper 1, and available on Paper 3
Paper 1 and Paper 3

Biological Molecules is examined on Papers 1 and 3 of AQA Biology, which draw on topics 1 to 4.

256 recall questions across 22 subtopics.

Sample questions from Biological Molecules

Answer each one closed book first, then open the answer.

Monomers, polymers, condensation and hydrolysis

What monomers are joined together to form proteins?

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Amino acids.
Alpha and beta glucose, amylose and amylopectin

Name the unbranched polysaccharide component of starch.

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Amylose
Triglycerides, fatty acids and phospholipid structure

What type of chemical bond forms when glycerol reacts with a fatty acid?

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An ester bond.
The general structure of amino acids

What is the chemical formula of the carboxyl group in an amino acid?

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COOH
Activation energy, induced fit and enzyme specificity

How does the induced-fit model describe the interaction between the active site and substrate during binding?

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The active site moulds around the substrate.
pH, temperature, initial rates and measurement uncertainty

How can the percentage error of a measurement be reduced?

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Measure a larger quantity with the same instrument, or use an instrument with a higher resolution.
Phosphodiester bonds and the DNA double helix

Describe the overall three-dimensional shape of a DNA molecule.

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A double helix
Semi-conservative replication, helicase and DNA polymerase

What happens to free DNA nucleotides once the template strand bases are exposed?

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Free DNA nucleotides are attracted to the exposed bases on the template strands.

The 22 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Monomers, polymers, condensation and hydrolysis	Recall questions on monomers and polymers, the monomers of carbohydrates, proteins and nucleic acids, and condensation and hydrolysis reactions as the making and breaking of bonds with water.	13
Monosaccharides, disaccharides and glycosidic bonds	Recall questions on monosaccharides as the monomers of carbohydrates, the condensation reaction that forms a glycosidic bond, and the monosaccharides that make up maltose, sucrose and lactose.	10
Alpha and beta glucose, amylose and amylopectin	Recall questions on the alpha and beta isomers of glucose, which isomer builds glycogen, starch and cellulose, and the chain shape and glycosidic bonds of amylose and amylopectin.	11
How starch, glycogen and cellulose suit their functions	Recall questions on how the helical, insoluble structure of starch suits storage in plants, why the branching of glycogen allows rapid energy release in animals, and how cellulose chains are bonded together.	10
Cellulose microfibrils and tests for sugars and starch	Recall questions on cellulose microfibrils in plant cell walls, Benedict's test for reducing sugars, the hydrolysis step in the test for non-reducing sugars, and the iodine test for starch.	12
Triglycerides, fatty acids and phospholipid structure	Recall questions on how glycerol and three fatty acids condense to form a triglyceride with ester bonds, saturated and unsaturated fatty acids, and how a phospholipid differs from a triglyceride.	12
Properties of lipids and the emulsion test	Recall questions on why triglycerides are hydrophobic and energy-rich stores, how amphipathic phospholipids form bilayers, and each step and result of the emulsion test for lipids.	12
The general structure of amino acids	Recall questions on amino acids as the monomers of proteins, the central carbon with its amine group, carboxyl group, hydrogen and R group, and how the twenty common amino acids differ.	11
Peptide bonds, polypeptides and bonds in proteins	Recall questions on the condensation reaction that forms a peptide bond, dipeptides and polypeptides, and the hydrogen bonds, ionic bonds and disulfide bridges that hold a protein's structure.	9
Levels of protein structure, the biuret test and chromatography	Recall questions on the primary, secondary, tertiary and quaternary structure of proteins, why shape matters, the biuret test for proteins, and separating amino acids by chromatography.	13
Activation energy, induced fit and enzyme specificity	Recall questions on how enzymes lower activation energy, the induced-fit model and why it replaced the lock-and-key model, enzyme-substrate complexes and why enzymes are specific.	11
Enzyme and substrate concentration and inhibition	Recall questions on how enzyme and substrate concentration affect the rate of reaction, saturation of active sites, and how competitive and non-competitive inhibitors affect rate and Vmax.	11
pH, temperature, initial rates and measurement uncertainty	Recall questions on how pH and temperature affect enzyme activity and denaturation, finding initial rate with a tangent, and accuracy, precision, uncertainty, percentage error and controls in enzyme investigations.	30
DNA, RNA and the components of a nucleotide	Recall questions on the roles of DNA and RNA, nucleotides as the monomers of nucleic acids, the pentose sugar, phosphate group and organic base, and deoxyribose in DNA.	10
Base pairing in DNA and RNA	Recall questions on complementary base pairing of adenine, thymine, guanine and cytosine in DNA, uracil replacing thymine in RNA, and how the pentose sugars of DNA and RNA differ.	9
Phosphodiester bonds and the DNA double helix	Recall questions on phosphodiester bonds formed by condensation between nucleotides, the double helix of two polynucleotide strands held by hydrogen bonds, and how RNA compares in length and strands.	8
Doubts about DNA, base ratios and RNA structure	Recall questions on why scientists first doubted that DNA carried the genetic code, calculating base percentages from complementary pairing, and ribose and the polynucleotide structure of RNA.	8
Semi-conservative replication, helicase and DNA polymerase	Recall questions on what semi-conservative replication means, how DNA helicase breaks hydrogen bonds to separate the strands, how free nucleotides pair with the template, and the role of DNA polymerase.	11
Steps of replication and the Meselson-Stahl experiment	Recall questions on the sequence of semi-conservative replication, the conservative, semi-conservative and dispersive models, and how Meselson and Stahl used nitrogen isotopes and banding patterns to test them.	14
ATP structure, hydrolysis and resynthesis	Recall questions on ATP as a nucleotide derivative, its hydrolysis by ATP hydrolase to release energy and phosphorylate compounds, and its resynthesis by ATP synthase in photosynthesis and respiration.	14
Water as a metabolite, solvent and coolant	Recall questions on water in condensation and hydrolysis reactions, its high heat capacity and latent heat of vaporisation, cohesion and surface tension from hydrogen bonding, and water as a polar solvent.	17
Hydrogen, iron, sodium and phosphate ions	Recall questions on inorganic ions in organisms, hydrogen ions and pH, iron ions in haemoglobin, sodium ions in the co-transport of glucose and amino acids, and phosphate ions in DNA and ATP.	16

Biological Molecules is 272 of the 1,977 questions in the guide.Get the guide, £8

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.