Circle the correct item. 1) Biological clock is a popular name given to a timing system

1) Biological clock is a popular name given to a … timing system.

a) mysterious

b) enigmatic

c) secretive

2) It keeps accurate … of days, weeks, months and even years.

a) period

b) time

c) amount

3) The biological clock in … times our periods of sleep and wakefulness and many body activities.

a) human beings

b) people

c) persons

4) No one knows where this biological clock is … or how it works.

a) located

b) situated

c) set

5) Scientists hope that experiments with plants and animals in outer space may provide more information about how biological clock …

a) does a job

b) does an activity

c) works

6) Biological clocks keep track of rhythmic changes in the …

a) environment

b) habitat

c) territory

7) The biorhythms of each … species seem to be timed to enable the organism to take advantage of the changes in its environment.

a) certain

b) particular

c) specific

8) But the biorhythms can be shifted - and the biological clock reset - by …at which the plant or animal gets light.

a) time period

b) changing the time

c) amount

9) Biological clocks in people work on schedules essential to life and …

a) health

b) no illness

c) no disease

10) Each is timed … when it can do the greatest good for the entire body

a) to use

b) to operate

c) to control