En anglais

Variation Within and Between Species

Science · Ecosystems & Habitats · ages 12-13

Name ______________________ Date ____________

A record uses ABO blood groups A, B, AB and O. Why is this discontinuous variation even though AB includes both letters?
- AB is halfway along a continuous scale from A to B.
- A, B, AB and O are separate categories with no scale.
- Only A and B count; AB and O are measurement errors.
Which observation shows continuous variation within a species?
- Heights measured in a group of humans
- ABO groups recorded in a group of humans
- Fur on cats compared with feathers on birds
Environmental causes of variation include things like diet and sunlight.
Circle one: True False
Invented student heights are grouped in cm. Each bar counts students in a range. Which range has the most students?
- 140 to <150 cm
- 160 to <170 cm
- 180 to <190 cm
Alex and Sam are identical twins with very similar genes. Alex has spent more time in sunlight and has a stronger tan. Which factor best explains the difference in tanning?
- Different genes inherited from their parents
- Different exposure to sunlight in daily life
- Different ABO blood groups changing skin tone
Maya's natural hair texture resembles her mother's and grandmother's. Which explanation does this family pattern support without proving its cause?
- Inherited genes could contribute to their similar hair texture.
- The same daily diet must be the only cause of their hair texture.
- Their ABO blood groups must be the only cause of their hair texture.
A gardener grows many plants from seeds made by crossing two genetically different parents, and many from cuttings of one plant. Both groups grow in the same conditions. Which group would you expect to have more genetic variation?
- The plants grown from the single parent's cuttings
- Both groups must have identical genetic variation
- The plants grown from the crossed seeds
A farmer says, 'My cloned plants have the same genes, so changing their soil cannot affect their growth.' Which response takes both genes and environment into account?
- Clones must grow identically in every soil because their inherited genes are copied.
- Richer soil always changes clones' inherited genes, so they stop being genetic copies.
- Both genes and soil affect growth, so clones can grow differently.

Answer key

For grown-ups. Fold this page away before handing over the rest.

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A, B, AB and O are separate categories with no scale. · AB is a valid category of its own. The four ABO groups are separate categories, not positions on a measurement scale.
Heights measured in a group of humans · Human heights allow intermediate measurements within one species. ABO groups are separate categories. Comparing cats with birds describes differences between species.
True · Diet and sunlight are environmental factors. Diet can affect growth, and extra sun exposure can cause tanning.
160 to <170 cm · The 160 to <170 cm range has 14 students. That exceeds the other counts of 2, 9, 5 and 1, so it has the most students.
Different exposure to sunlight in daily life · Their genes are very similar, but their sun exposure differs. Extra sunlight can cause tanning, so an environmental factor best explains the described difference.
Inherited genes could contribute to their similar hair texture. · Inherited genes influence natural hair texture. Family resemblance supports an inherited explanation, but the resemblance alone does not prove what caused it.
The plants grown from the crossed seeds · The crossed seeds inherit different combinations of genetic material from two different parents. Cuttings usually copy one parent's genes, apart from mutations, so more genetic variation is expected among the seed-grown plants.
Both genes and soil affect growth, so clones can grow differently. · Having the same genes does not prevent environmental effects. Soil conditions can affect growth without changing the plants' inherited genes.