7th grade · Science · Unit 1 of 10
Natural Selection
How species adapt and change
What your child practices
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.
Minnesota K-12 Academic Standards benchmark: 7L.2.2.1.1; 7L.3.2.1.4 · how natural selection changes the traits in a population over time
How we explain it
Children can open this short lesson before they practice.
- Inherited traits come from parents in genes. Acquired traits are learned or gained during one life and are not passed on.
- Members of a species vary. Those best suited to their surroundings survive and have more young.
- Over many generations, the helpful traits become more common in the population.
Example: Mice live on dark soil, and owls hunt them by sight. Which mice will become more common? Owls spot light mice more easily on dark soil. Dark mice survive and have more young. Their color is inherited, so it spreads. Answer: dark mice
Natural Selection in Minnesota
In the Minnesota K-12 Academic Standards, this is unit 1 of 10 in 7th grade Science, before Cells: Life's Building Blocks.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
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
A cactus has thick stems that store water and spines instead of leaves. These are adaptations to…
🌵- a hot, dry desert
- a freshwater pond
- a shady rainforest floor
- a cold ocean
a hot, dry desert
Hint: Storing water and losing less of it through leaves helps a plant where rain is rare.
Question 2
Bacteria are treated with an antibiotic. A few have a trait that lets them survive it. What happens over many generations?
🧫- All bacteria disappear forever
- Antibiotic-resistant bacteria become more common
- Nothing changes in the population
- 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.
Question 3
What does 'variation' mean in biology?
- Differences between a plant and an animal
- Differences in traits among individuals of the same species
- The way a species stays exactly the same for millions of years
- Changes in the weather from season to season
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 4
What is an adaptation?
🦎- A habit an animal learns by watching others
- A change an animal decides to make during its life
- An inherited trait that helps a living thing survive and reproduce in its environment
- Any trait at all, even one that makes survival harder
An inherited trait that helps a living thing survive and reproduce in its environment
Hint: Adaptations are passed down through genes and make an organism better suited to where it lives.
Question 5
What is a mutation?
🧬- A trait learned from a parent
- A change in an organism's DNA that can create a new trait
- A type of fossil
- An injury that heals over time
A change in an organism's DNA that can create a new trait
Hint: Mutations are one source of new variation. Natural selection then acts on that variation.
Question 6
Which is the best evidence that living things have changed over a very long time?
🦴- Leaves changing color in autumn
- A puppy growing into a dog
- Daily weather forecasts
- Fossils found in layers of rock
Fossils found in layers of rock
Hint: Fossils preserve organisms from long ago. Older rock layers hold fossils that look different from life today.