G4 Skeleton and Muscles Active Science Chapter 1

Why do animals without skeletons move differently from animals with skeletons?

• Animals without skeletons move by rolling on the ground like a ball.
• Animals without skeletons move using muscle contractions, then it is slow while those with skeletons use it for movement becoming faster

• Animals with skeletons use only their muscles to move without any structure.
• Animals without skeletons move using muscle contractions then it is fast, while those with skeletons use it for movement becoming slower

Explain how muscles and bones work together when you pick up something heavy.

• Muscles push against bones to create friction for lifting.
• Muscles contract to pull on bones, allowing movement and support to lift heavy objects.
• Bones contract to lift heavy objects without muscle involvement.
• Muscles and bones do not interact when lifting heavy items.

Imagine your skeleton didn’t protect your lungs. What might happen to your body?

• The lungs will become stronger and more resilient.
• The lungs could be damaged because it is soft, then we could stop breathing

• The body will adapt by increasing lung capacity.
• The heart will take over lung functions completely.

Compare the importance of the skull and the ribcage in protecting internal organs. Which one do you think is more important, and why?

• The skull is more important for protecting internal organs.
• The ribcage is more important for protecting the brain.
• Both the skull and ribcage are equally important to protect very special organs.

• The skull is less important than the ribcage for protecting the heart.

Look at two animals: a crab and a human. How are their skeletons different, and how does this affect how they live or move?

• Humans have a shell-like structure, while crabs have a flexible spine.
• Crabs have an exoskeleton, while humans have an endoskeleton, affecting their movement and habitat.
• Both crabs and humans have no skeletons, relying on muscles alone.
• Crabs have an endoskeleton, while humans have an exoskeleton. affecting their movement and habitat.

What might happen if a snail’s shell is cracked or broken?

• The snail will grow a new shell immediately.
• The snail will become faster and more agile.
• The snail will more likely to be eaten by other animals and it can dry out.

• The snail will start to fly to escape danger.

Explain why a bird’s hollow (not solid inside) bones help it to fly.

• Hollow bones help birds store more food for energy.
• Hollow bones provide insulation against cold temperatures.
• Hollow bones increase the bird's overall size for better aerodynamics.
• Hollow bones make the body lighter, making it easier to fly.

Why do you think animals with exoskeletons are usually smaller than animals with endoskeletons?

• Exoskeletons provide better support for larger bodies.
• Animals with exoskeletons have no growth limitations.
• Endoskeletons are more efficient for all animal sizes.
• Animals with exoskeletons are usually smaller because exoskeletons are hard and heavy.

An octopus has no skeleton. How does this affect the way it lives?

• The octopus has a rigid body structure for protection.
• The octopus relies on a hard shell for defense.
• The octopus cannot change its shape or size.
• The octopus can squeeze into small spaces to hide from predator then it can change shape too.

Compare what happens when you bend your knee and when you straighten it. (Choose 2 answers)

• When you bend your knee the biceps will contracts and the triceps will relaxes

• When you bend your knee the biceps will relaxes and the triceps will contracts

• When it straighten your biceps will contracts and triceps will relaxes

• When it straighten your biceps will relaxes and triceps will contracts