Variation and inheritance, adaptations in animals and plants, competition and environmental factors, natural selection and antibiotic resistance, biodiversity and conservation, and biotic and abiotic factors in ecosystems.

What is variation?

Differences in characteristics between individuals in the same species.

What is an adaptation?

A feature that helps an organism survive and reproduce in its environment.

What is the difference between inherited and environmental variation?

Inherited variation comes from genes; environmental variation comes from conditions the organism lives in.

Why does a hydrangea’s flower colour change in different soil types?

Because soil pH affects ion availability, which changes pigment expression.

How does thick fur help polar bears survive?

It provides insulation to reduce heat loss in cold environments.

Why do plants grow more slowly in shaded areas?

They receive less light, so photosynthesis is reduced and less energy is available for growth.

What might happen if a polar bear loses its insulating fat layer?

It could lose heat quickly and struggle to survive in the cold.

What is likely to happen to a plant that receives more water and light than another?

It is likely to grow taller because it can photosynthesise more and produce more energy.

What would happen to a cactus without its waxy layer?

It would lose water quickly and might not survive in the dry desert environment.

What does the IQ data suggest about identical twins raised apart?

They can develop different IQs, showing environmental factors influence intelligence.

In Figure 5, which plant is more affected by light distance and how can you tell?

Plant B, because its percentage cover drops more sharply as distance from the hedge increases.

How do you calculate the percentage cover in a quadrat?

Count the number of squares with the species, divide by total squares, and multiply by 100.

Why can identical twins have different characteristics?

Because even with the same genes, different environments lead to different outcomes.

How do both genes and environment affect height?

Genes determine potential height; environment (like diet) influences whether that potential is reached.

How does camouflage help predators survive?

It makes them harder to spot by prey, improving their hunting success.

What is natural selection?

The process by which species evolve; organisms with advantageous traits survive and reproduce.

What is an antibiotic?

A medicine that kills bacteria or stops them from growing.

How can a bacterium become antibiotic-resistant?

By mutation, which may produce a version that is not killed by antibiotics.

Why do bacteria reproduce quickly?

Because they divide rapidly—this allows advantageous mutations to spread fast.

What is meant by a ‘superbug’?

A strain of bacteria resistant to multiple antibiotics, e.g. MRSA.

How can antibiotic resistance be reduced in hospitals?

By using antiseptics, disinfectants, sterile equipment, and prescribing antibiotics only when necessary.

Why should hospitals avoid overusing antibiotics?

Because it increases the chances of resistant bacteria surviving and spreading.

What is biodiversity?

The variety of all different species of organisms on Earth or within a specific ecosystem.

Why is biodiversity important to ecosystems?

It helps maintain stability—organisms depend on each other for food and shelter.

How do conservation and seed banks help protect biodiversity?

They preserve species and genetic material, especially for endangered species.

Why can maintaining genetic diversity in breeding programmes be difficult?

It may involve only a small number of individuals, risking inbreeding.

Give one benefit and one problem with captive breeding.

Benefit: protects endangered species. Problem: animals may not survive if released into wild.

What are biotic factors in an ecosystem?

Living things that affect other organisms, like predators, competition, and disease.

What are abiotic factors in an ecosystem?

Non-living environmental conditions like temperature, rainfall, and light intensity.

How does temperature affect plant growth?

Too cold and the rate of photosynthesis slows; too hot and enzymes may be damaged.