Multiple choice

1. What part of the lower respiratory tract is made up of tiny air sacs where oxygen and carbon dioxide are exchanged?

A. Bronchioles 

B. Alveoli 

C. Trachea

D. Larynx

2. All the systems of the body work together to keep the internal environment of the body constant within certain limits. This process is called

A. homoeostasis. 

B. positive feedback. 

C. neuroglia.

D. homeopathy.

3. What divides the human heart into a left and right side?

A. Aaorta 

B. Septum 

C. Ventricles

D. Atria

4. The main sex hormone in males is

A. estrogen. 

B. progesterone. 

C. testosterone.

D. luteum.