1 In multicellular organisms, cells must be able to communicate with each other. Structures that enable most cells to communicate with each other are known as

(1) pathogenic agents       (3) antibiotics
(2) chloroplasts                (4) receptor molecules

1         2         3         4        

Every single-celled organism is able to survive because it carries out

(1) metabolic activities
(2) autotrophic nutrition
(3) heterotrophic nutrition
(4) sexual reproduction

1         2         3         4        

3 Which statement describing the cells in a body system is correct?

1 Each cell in the system is identical to the other cells in the system, and each cell works independently of the other cells.
2 Some cells in the system may be different from the other cells in the system, but all cells are coordinated and work together.
3 Each cell in the system is different from the other cells in the system,  and each cell works independently of the other cells.
4 All cells in the system are identical to each other and work together.

1         2         3         4        

4 The process of active transport requires the most direct use of

(1) carbon dioxide         (3) ATP
(2) amino acids             (4) glucose

1         2         3         4        

5 To communicate between cells, many multicellular animals use

1 nerve signals and respiratory gases
2 respiratory gases and hormones
3 bones and muscles
4 nerve signals and hormones

1         2         3         4