GCSE Biology practice quiz

The cell membrane is partially permeable and controls the movement of substances in and out, while the nucleus holds the DNA.

Plant cell walls are made of cellulose, which strengthens the cell. Starch is a storage carbohydrate and chlorophyll is a pigment.

High temperature changes the shape of the enzyme, so the active site no longer fits the substrate. This is called denaturing.

Iodine solution turns blue-black with starch, and the other nutrients need different tests.

Villi greatly increase the surface area, and they have a rich blood supply to carry absorbed molecules away.

A vaccine contains a safe form of the pathogen or its antigens, so the immune system can respond quickly if the real pathogen arrives later.

Plants take in carbon dioxide and water and, using light energy, make glucose and release oxygen.

Human muscles make lactic acid when there is not enough oxygen. Yeast makes ethanol and carbon dioxide instead.

Insulin, made by the pancreas, causes cells to take up glucose from the blood.

Alleles are alternative forms of a gene, for example the alleles for different eye colours.

The cross gives BB, Bb, Bb and bb, so one in four offspring is bb.

Mitosis makes two daughter cells identical to the parent cell, for growth and repair. Meiosis makes gametes.

Osmosis is specifically the movement of water across a partially permeable membrane. Diffusion is the more general movement of particles.

Arteries have thick, elastic walls to cope with high pressure. Veins carry blood back towards the heart.

Xylem carries water and mineral ions upwards. Phloem carries dissolved sugars.

Moving air carries away water vapour near the leaf, keeping the concentration gradient steep, so transpiration increases.

Antibiotics target bacteria. Viruses live inside host cells and need other approaches such as vaccination.

When extra light makes no difference, something else, such as carbon dioxide concentration or temperature, is in short supply and limiting the rate.

Negative feedback detects a change and triggers a response that opposes it, as in control of body temperature and blood glucose.

Variation exists in a population, and organisms better suited to the environment tend to survive, breed and pass on the alleles involved.

The producer makes its own food by photosynthesis, and grass is the only organism here that does that.

Decomposers work best when it is warm, moist and there is oxygen for aerobic respiration.

Random placement avoids choosing the areas you expect to give a particular result, so the sample is more representative.

Independent variable means the one you change, dependent variable is what you measure, and control variables are kept constant.