Paper 1: Biological processes

A cell is 40 µm long. In a drawing it is 80 mm long. What is the magnification?

Which test would give a positive result with a non-reducing sugar only after boiling with acid?

A DNA sample contains 22% adenine. What percentage is cytosine?

Which statement describes a non-competitive inhibitor?

Which molecule crosses the phospholipid bilayer most rapidly by simple diffusion?

In which stage of mitosis do chromosomes line up on the equator?

Which feature of the lungs maintains a steep concentration gradient for oxygen?

Which vessel carries blood at the highest pressure?

Which of these increases the rate of transpiration?

What is the approximate resting potential of a neurone?

Which cells in the islets of Langerhans secrete insulin?

Where does selective reabsorption of glucose mainly occur?

Which enzyme fixes carbon dioxide in the Calvin cycle?

How many ATP molecules are produced directly in the Krebs cycle per glucose?

A student repeats a measurement five times and gets very similar values that are all far from the true value. The results are:

Haemoglobin is a globular protein with a quaternary structure. Explain what is meant by quaternary structure and how the structure of haemoglobin relates to its function.

Explain how the hydrogen bonding between water molecules is important for living organisms. Give three different examples.

Describe how you would investigate the effect of temperature on the permeability of beetroot cell membranes.

Explain why more pigment leaks out at high temperatures.

Describe the events of the cell cycle, including checkpoints.

Explain why damage to the genes that control checkpoints can lead to cancer.

Describe the mechanism of inspiration in a mammal.

A spirometer trace showed 18 breaths in 1 minute, each with a tidal volume of 0.45 dm³. The oxygen chamber volume fell by 1.2 dm³ in 3 minutes. Calculate the ventilation rate and the rate of oxygen uptake.

Explain how sucrose is transported from a leaf to a root by translocation.

Describe three adaptations of marram grass that reduce water loss.

Explain how summation at synapses can affect whether an action potential is produced in a postsynaptic neurone.

Explain why the speed of conduction in a myelinated neurone is faster than in an unmyelinated neurone.

Describe how insulin release is controlled by beta cells.

Give three advantages of producing insulin using genetically modified bacteria rather than extracting it from animals.

A person's kidney filters 125 cm³ of blood plasma per minute. Glucose concentration in the plasma is 1.0 mg cm⁻³. Calculate the mass of glucose filtered per day in grams, and explain why none normally appears in the urine.

Explain how the loop of Henle allows the production of concentrated urine.

Describe the role of the electron transport chain in aerobic respiration.

Compare the processes of photosynthesis and aerobic respiration.

A student measured the rate of respiration of maggots at five temperatures using a respirometer. Suggest how she could: (a) improve the validity of the results; (b) process the data to show the effect of temperature; (c) estimate the uncertainty in the volume readings.

Describe how the electrical activity of the heart coordinates the cardiac cycle.

Explain how the liver deals with excess amino acids.