Heredity: common misconceptions

If your child says… “Each new difference wipes out the old ones.”

Ask together

Which marks remain together in the lowest bacterium?

What’s true

A descendant can retain an earlier DNA change alongside a new one.

If your child says… “The birds make green beetles turn brown.”

Ask together

Were brown beetles present before the birds arrived?

What’s true

Predation favours brown beetles already present, whose surviving descendants can become more common.

If your child says… “Two tall Tt plants can only have tall offspring.”

Ask together

What gene pair forms when each parent passes on t?

What’s true

Dominant T hides recessive t's effect without removing t.

If your child says… “Shortness and wrinkled seeds must always stay together.”

Ask together

Which offspring pictures combine short plants with round seeds?

What’s true

The chapter's independently inherited pea traits can appear in combinations absent from the original parents.

If your child says… “A gene turns into the plant's stem.”

Ask together

What lies between the gene's instructions and growth in this diagram?

What’s true

In peas, genes affect proteins that help make growth hormone, which influences stem growth.

If your child says… “The offspring gets twice the parents' chromosome number.”

Ask together

Did each gamete receive whole pairs or one member from each?

What’s true

Each gamete supplies half the body-cell chromosome number, so joining restores the usual number.

If your child says… “Every species uses X and Y, just like humans.”

Ask together

How could the human chromosome rule alone explain the temperature effect shown here?

What’s true

The human XX–XY pattern does not apply to every species.

If your child says… “Two sons mean the next baby must be a girl.”

Ask together

Can earlier births stop either kind of sperm fertilising the next egg?

What’s true

Earlier births do not determine whether an X-bearing or Y-bearing sperm fertilises the next egg.