Questions: Comparing Life Cycles

Question 1

A fruit fly's life cycle takes about 30 days. An elephant's takes about 70 years to reach full maturity. What is the same about both life cycles?

• A. Nothing — they are completely different
• B. Both include the same basic stages: being born, growing, becoming an adult, and having offspring
• C. Both animals lay eggs
• D. Both animals go through metamorphosis

Answer: (B)

Despite being wildly different in speed and detail, both life cycles follow the same pattern: the organism begins life, grows and develops, reaches adulthood, reproduces, and the next generation starts the cycle again. The basic plan is the same even though the details differ enormously.

Question 2

Most animals that lay eggs are birds.

• T. True
• F. False

Answer: False

Many different animal groups lay eggs. Fish, reptiles (like turtles and crocodiles), amphibians (like frogs), and insects all lay eggs. Even a few mammals lay eggs — the platypus and the echidna. Egg-laying is very common across the animal kingdom, not just in birds.

Question 3

Name two differences between the life cycle of a butterfly and the life cycle of a dog.

Model answer: A butterfly goes through metamorphosis (egg, caterpillar, chrysalis, butterfly) while a dog does not — a puppy looks like a small adult dog. Also, a butterfly hatches from an egg while a puppy is born live from its mother.

These two life cycles are very different in their details. The butterfly changes its body shape completely through metamorphosis. The dog just grows bigger while keeping the same basic form. The butterfly starts as an egg; the dog is born live. Yet both follow the same underlying pattern: start life, grow, become an adult, have offspring.