Grade 7 Natural Selection worksheet
from Gradelings · Name: ______________________
How to explain it
- 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 colour is inherited, so it spreads. Answer: dark mice
Question 1
Which trait would best help a fox survive in the snowy Arctic?
🦊- thin fur and large ears
- dark fur and a bare tail
- thick white fur and small ears
- short fur that sheds in winter
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 2
Why is variation important for a species when its environment changes?
- It stops the environment from changing
- It guarantees every individual survives
- Some individuals may have traits that help them survive the new conditions
- It means the species can never go extinct
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 3
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 Light moths Dark moths 1 50 50 2 40 60 3 29 71 4 21 79 - Birds cannot see any of the moths at all
- Light moths change colour during their lives to match the ground
- The moths decide to have dark offspring so they can hide
- 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 4
Inherited or acquired? Sort each trait.
Sort into: 🧬 inherited (in the genes) · 🏋️ acquired during life
- 🐕a dog that learned to sit
- 💪muscles built by lifting weights
- 🌵a cactus's sharp spines
- 🚲knowing how to ride a bike
- 🐅a tiger's stripe pattern
- 🐦a finch's beak shape
- 🩹a scar from a cut
- 🌺a flower's petal colour
🧬 inherited (in the genes): a cactus's sharp spines, a tiger's stripe pattern, a finch's beak shape, a flower's petal colour · 🏋️ acquired during life: a dog that learned to sit, muscles built by lifting weights, knowing how to ride a bike, a scar from a cut
Hint: Inherited traits are passed from parents to offspring in their genes. Acquired traits are gained during one organism's life and are not passed on to its offspring.
Question 5
Farmers breed only the cows that give the most milk. Over many generations, the herd gives more milk. This is called…
🐄- natural selection
- artificial (selective) breeding
- camouflage
- extinction
artificial (selective) breeding
Hint: Here people, not nature, choose which animals reproduce.
Question 6
What does 'variation' mean in biology?
- Changes in the weather from season to season
- Differences between a plant and an animal
- The way a species stays exactly the same for millions of years
- Differences in traits among individuals of the same species
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 7
Which of these is NOT needed for natural selection to happen?
- More offspring born than can survive
- Variation in traits within a population
- Traits passed from parents to offspring
- Animals deciding to change their bodies
Animals deciding to change their bodies
Hint: Natural selection needs variation, inheritance and competition to survive. Nobody chooses their inherited traits.
Question 8
In natural selection, what does 'survival of the fittest' really mean?
- Individuals best suited to their environment are more likely to survive and reproduce
- The biggest, strongest animal always wins
- Only predators survive, never prey
- Animals that exercise the most live the longest
Individuals best suited to their environment are more likely to survive and reproduce
Hint: 'Fit' means 'a good fit' for the environment, like a key that fits a lock, not physically strong.
Question 9
Which scientist proposed the theory of evolution by natural selection after studying finches, tortoises and other species?
🐢- Marie Curie
- Isaac Newton
- Charles Darwin
- Dmitri Mendeleev
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 10
A class modelled lizards living on black volcanic rock. Hawks hunt them by sight. Which colour is natural selection favouring here?
A sample of 100 lizards in each generation Generation Pale lizards Dark lizards 1 46 54 2 35 65 3 24 76 4 16 84 - neither: the numbers stay about the same
- dark lizards
- pale lizards
dark lizards
Hint: Look for the column whose numbers go up each generation. Those individuals are surviving and reproducing more.
Answer key
- 1. thick white fur and small ears
- 2. Some individuals may have traits that help them survive the new conditions
- 3. Dark moths are harder for birds to spot, so more survive and reproduce
- 4. 🧬 inherited (in the genes): a cactus's sharp spines, a tiger's stripe pattern, a finch's beak shape, a flower's petal colour · 🏋️ acquired during life: a dog that learned to sit, muscles built by lifting weights, knowing how to ride a bike, a scar from a cut
- 5. artificial (selective) breeding
- 6. Differences in traits among individuals of the same species
- 7. Animals deciding to change their bodies
- 8. Individuals best suited to their environment are more likely to survive and reproduce
- 9. Charles Darwin
- 10. dark lizards
Want more than 10 questions?
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