Grade 7 · Science · Unit 9 of 9
Natural Selection
How species adapt and change
What your child practises
Variation, inherited versus acquired traits, adaptations, and how natural selection changes populations over generations, with fossils and other evidence. Includes reading data from a predator–prey model.
New Brunswick Curriculum skill descriptor: Scientific Literacy: Sensemaking · how living things change over time
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Why is variation important for a species when its environment changes?
- It means the species can never go extinct
- It guarantees every individual survives
- Some individuals may have traits that help them survive the new conditions
- It stops the environment from changing
Some individuals may have traits that help them survive the new conditions
Hint: If every individual were identical, one change could harm them all. Differences give some a chance.
Question 2
What does 'variation' mean in biology?
- The way a species stays exactly the same for millions of years
- Differences in traits among individuals of the same species
- Changes in the weather from season to season
- Differences between a plant and an animal
Differences in traits among individuals of the same species
Hint: Look at a group of people, dogs or sunflowers: no two are exactly alike. Those differences are variation.
Question 3
Which trait would best help a fox survive in the snowy Arctic?
🦊- short fur that sheds in winter
- dark fur and a bare tail
- thin fur and large ears
- thick white fur and small ears
thick white fur and small ears
Hint: Thick fur keeps heat in, small ears lose less heat, and white fur hides the fox in the snow.
Question 4
Which scientist proposed the theory of evolution by natural selection after studying finches, tortoises and other species?
🐢- Dmitri Mendeleev
- Isaac Newton
- Charles Darwin
- Marie Curie
Charles Darwin
Hint: He sailed on HMS Beagle to the Galápagos Islands. Alfred Russel Wallace came up with the same idea on his own.
Question 5
A class modelled moths living on tree bark darkened by soot. Birds hunt them by sight. What best explains the pattern in the table?
A sample of 100 moths in each generation Generation Dark moths Light moths 1 45 55 2 58 42 3 68 32 4 77 23 - Birds cannot see any of the moths at all
- The moths decide to have dark offspring so they can hide
- Light moths change colour during their lives to match the ground
- Dark moths are harder for birds to spot, so more survive and reproduce
Dark moths are harder for birds to spot, so more survive and reproduce
Hint: Individuals can't change their inherited colour. Those that blend in are eaten less, so they live to pass their colour on to more offspring.
Question 6
Bacteria are treated with an antibiotic. A few have a trait that lets them survive it. What happens over many generations?
🧫- Nothing changes in the population
- All bacteria disappear forever
- Antibiotic-resistant bacteria become more common
- The bacteria learn to resist the drug on purpose
Antibiotic-resistant bacteria become more common
Hint: The survivors reproduce and pass on their resistance. This is natural selection happening fast.