Paper 1 (topics 1–4)

Describe the primary, secondary and tertiary structure of a protein.

Describe the biuret test for proteins.

Explain how a non-competitive inhibitor reduces the rate of an enzyme-controlled reaction.

Product formed by an enzyme (data are illustrative, written for this paper):

Time / s	0	10	20	30
Product / µmol	0	18	30	36

Calculate the initial rate of reaction and explain why the rate decreases over time.

Give three differences between DNA and RNA.

In a sample of DNA, 22% of the bases are adenine. Calculate the percentage of guanine. Explain your answer.

Explain how hydrogen bonding gives water properties that are important to organisms.

Give two roles of phosphate ions in cells.

Describe how HIV replicates inside a host cell.

Compare the transmission electron microscope with the optical microscope.

40 eyepiece graticule divisions match 100 µm on a stage micrometer. A cell is 18 divisions long. Calculate its length.

Explain how the structure of a channel protein allows facilitated diffusion of ions.

Plant cells with a water potential of −600 kPa are placed in a solution with a water potential of −400 kPa. Explain what happens.

Explain why the secondary immune response is faster and greater than the primary response.

Explain why a new influenza vaccine is needed each year.

Explain how xerophytic plants reduce water loss.

Explain how air moves into the lungs during inspiration.

A person has a heart rate of 70 beats per minute and a stroke volume of 75 cm³. Calculate the cardiac output in dm³ min⁻¹ and explain what it shows.

Explain the Bohr effect and its advantage during exercise.

In a ringing experiment, a ring of bark (including phloem) was removed from a tree trunk. The bark above the ring swelled. Explain what this shows about translocation.

Give two pieces of evidence against the mass flow hypothesis.

Describe the process of transcription.

Explain why pre-mRNA in eukaryotes is spliced.

Explain how non-disjunction during meiosis can result in a person with Down's syndrome.

Explain what is meant by stabilising selection, using birth mass as an example.

Explain how the binomial naming system and the phylogenetic hierarchy are used to classify organisms.

Explain how farming techniques can reduce biodiversity.

Explain why small mammals have a higher metabolic rate per gram of body mass than large mammals.

Compare the structures of starch and glycogen and explain how each is suited to its role.

Explain why triglycerides are a good energy store.

Describe and explain the role of ATP in muscle contraction and in the active transport of ions.