Living things and keys — final check

1. describe

Describe what is meant by (a) growth, (b) excretion and (c) sensitivity in living organisms.

(a) Growth

(b) Excretion

(c) Sensitivity

2. evaluate

A wind-up toy dog walks across the floor, and its tail wags when you press its nose. A pupil says the toy is alive because it moves and responds to touch. Explain whether the pupil is right.

3. construct / identify

A crab has ten legs and a hard shell. A ladybird has six legs and spotted wing cases. A spider has eight legs. An earthworm has no legs. (a) Construct a dichotomous key for these four animals. (b) Use your key to show the steps that lead to the crab.

(a) Your key

(b) Route to the crab

4. calculate

A dichotomous key is made for 20 kinds of seaweed found on one beach. How many pairs of statements does it need?

Number of pairs of statements: ______________ unit ________

5. describe

Describe the binomial system of naming species. Use Homo sapiens as an example.

6. explain

A zebra and a horse can mate and produce a zorse. Zorses are infertile. Explain whether zebras and horses are the same species.

7. explain

Supplement. Explain how comparing the DNA base sequences of three species can show which two are most closely related.