Explaining Change: Genetics, Evolution and Reactions

One idea: change

Biology and chemistry can feel like separate worlds, but this topic joins them with a single idea: change, and what causes it. Genes and inheritance explain how features pass on. Natural selection explains how a whole species changes over time. And chemical reactions explain how substances change into new ones. This module looks at all three.

Variation and selection words

Four words span this whole topic, from genes to reactions.

Match the genetics word

Dominant or recessive?

A dominant allele shows in the offspring whenever it is present. When does a recessive allele show?

• Only when both alleles are recessive
• It always shows, like a dominant one
• It never shows at all
• Only in male offspring

Physical or chemical change?

Not every change makes a new substance. This is a key difference in chemistry.

Match the rate factor

The link is cause and effect

Whether it is a gene passing on, a species evolving, or substances reacting, this topic is about change and what causes it. In your answers, always name the cause of the change, not just the change itself.

Variation, genes and selection

Differences between individuals are called _____. Genes are carried on _____. Over many generations, _____ selection changes a species. A change that makes a new substance is a chemical _____. Heating a reaction usually makes it go _____.

Speeding up a reaction

Which of these would speed up a chemical reaction? Choose all that apply.

• Raising the temperature
• Increasing the concentration
• Adding a catalyst
• Cooling the mixture down
• Using larger lumps instead of powder

Find the chemical changes

Tap the two changes that are chemical changes, where a new substance is made.

• Wood burns to make ash and smoke.
• Iron rusts to form a new orange substance.
• Ice melts into water.
• Sugar dissolves in a cup of tea.

How natural selection works

Put the steps of natural selection into the right order.

• Individuals in a species show variation
• Some are better adapted to their environment
• The better-adapted are more likely to survive
• The survivors reproduce and pass on their genes
• Over generations the species changes

Energy in reactions

A reaction that transfers energy to the surroundings and makes them warmer is described as what?

• Exothermic
• Endothermic
• Physical
• Reversible

Change in a beetle population

A beetle lives on pale tree bark. Pollution then turns the bark dark. Choose what happens as natural selection acts.

• The bark is now dark. What does this mean for the beetles?
• Which beetles are now most likely to survive and reproduce?
• After many generations, what happens to the population?

Natural selection over time

Explain how natural selection can change a species over time. Use an example if you can.

• Start with variation in the species
• Explain which individuals survive and why
• Explain what happens over many generations