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Biology Grade 4-5 Answer Key

Biology: Animal Adaptations and Natural Selection

How traits help animals survive and reproduce

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Biology: Animal Adaptations and Natural Selection

How traits help animals survive and reproduce

Biology - Grade 4-5

Instructions: Read each problem carefully. Use complete sentences when explaining your thinking. Show your work in the space provided.
  1. 1

    A polar bear has thick fur and a layer of fat under its skin. Explain how these adaptations help it survive in the Arctic.

    Think about what the Arctic environment is like.

    Thick fur and a layer of fat help the polar bear stay warm in the cold Arctic. These traits help it survive long enough to hunt, grow, and reproduce.
  2. 2

    Is a giraffe's long neck a physical adaptation or a behavioral adaptation? Explain your answer.

    A giraffe's long neck is a physical adaptation because it is a body part. It helps the giraffe reach leaves high in trees.
  3. 3

    A rabbit freezes and stays very still when it senses a fox nearby. Is this a physical adaptation or a behavioral adaptation? Explain your answer.

    A behavior is something an animal does.

    Freezing and staying still is a behavioral adaptation because it is an action the rabbit does. This behavior can help the rabbit avoid being noticed by a predator.
  4. 4

    A bird population lives in an area with mostly small, soft seeds. Which beak would probably be most helpful: a short thin beak or a large thick beak? Explain why.

    Match the beak shape to the food type.

    A short thin beak would probably be most helpful for eating small, soft seeds. Birds with beaks that match their food source are more likely to get enough food and survive.
  5. 5

    Explain why camouflage can help a prey animal survive.

    Camouflage helps a prey animal blend in with its surroundings. This makes it harder for predators to see the animal, so it is more likely to survive.
  6. 6

    A group of moths lives on dark tree bark. Some moths are dark and some are light. Which moths are more likely to survive if birds hunt them by sight? Explain your answer.

    Think about which moth color is harder to see on dark bark.

    The dark moths are more likely to survive because they blend in with the dark tree bark. Light moths are easier for birds to see and catch.
  7. 7

    True or false: An individual animal changes its body on purpose because it needs to survive. Explain the correct idea.

    Natural selection happens to populations over time, not because one animal decides to change.

    False. Individual animals do not change their inherited traits on purpose. Natural selection happens when animals with helpful inherited traits survive and reproduce more often over many generations.
  8. 8

    A frog lays hundreds of eggs, but only some tadpoles survive to become adult frogs. How can this affect natural selection?

    Because not all tadpoles survive, those with helpful traits may be more likely to live and grow into adults. If they reproduce, those helpful traits can become more common in the frog population.
  9. 9

    Name one adaptation that helps a duck live in or near water. Explain how it helps.

    Think about a duck's feet, feathers, or beak.

    Webbed feet are one adaptation that helps a duck live near water. Webbed feet help the duck paddle and swim more easily.
  10. 10

    A desert fox has large ears. Explain how large ears might help the fox survive in a hot desert.

    Large ears can help a desert fox release heat from its body. This helps the fox stay cooler in a hot environment.
  11. 11

    Which trait would be more helpful for a fish that lives in fast-moving water: a flat, wide body that helps it stay close to rocks, or bright colors that make it easy to see? Explain your choice.

    Think about the challenge caused by the moving water.

    A flat, wide body that helps it stay close to rocks would be more helpful in fast-moving water. This trait can help the fish avoid being swept away.
  12. 12

    A snowy owl is white. Explain how this color can help it survive in a snowy habitat.

    A white color helps a snowy owl blend in with the snow. This camouflage can help it hide from prey and may also help it avoid danger.
  13. 13

    In a certain habitat, insects are the main food source for birds. Birds with longer beaks can reach insects inside cracks in tree bark. Over many generations, what might happen to the number of birds with longer beaks? Explain why.

    Helpful inherited traits can become more common over time.

    The number of birds with longer beaks might increase over many generations. Longer beaks help the birds get more food, so those birds may survive and reproduce more often.
  14. 14

    Give one example of a behavioral adaptation that helps an animal survive during cold seasons.

    Migration is one behavioral adaptation that helps some animals survive cold seasons. Animals may move to warmer places where food is easier to find.
  15. 15

    A student says, "All adaptations are helpful in every habitat." Explain why this statement is not correct.

    Think about a thick fur coat in a very hot desert.

    This statement is not correct because an adaptation is helpful in a specific environment. A trait that helps an animal in one habitat might not help, or might even be harmful, in a different habitat.
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