Foundations in biology

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?

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.

Explain the shape of the curve.

Explain how the movement of water through a plant depends on water potential gradients.

Sickle cell anaemia is caused by a substitution mutation in the β-globin gene. Explain how this mutation leads to sickle-shaped red blood cells.

A student used an eyepiece graticule. At ×400, 1 epu = 2.5 µm. A cell measured 18 epu long and 12 epu wide. Calculate the actual dimensions and the area of the cell, assuming it is rectangular.

Discuss how the structure of proteins is related to their functions in living organisms. Use examples from different areas of biology.

Explain why positive feedback is not usually used to maintain homeostasis, and give one example where it is useful.