Biology (Holt)

CHAPTER 4Cells and Their Environment 73

Quick Review Looking Ahead

Answer the following without referring to
earlier sections of your book.
1.Distinguishbetween polar and nonpolar
substances. (Chapter 2, Section 1)
2.Describethe function of ATP in cells.
(Chapter 2, Section 3)
3.Identifydifferent kinds of proteins that
compose the cell membrane.
(Chapter 3, Section 2)
4.Summarizethe function of vesicles and the
Golgi apparatus. (Chapter 3, Section 3)
Did you have difficulty? For help, review the
sections indicated.

Section 1

Passive Transport

Diffusion

Osmosis

Crossing the Cell Membrane

Section 2

Active Transport

Movement Against a Concentration Gradient

Movement in Vesicles

Membrane Receptor Proteins

http://www.scilinks.org

National Science Teachers Association sciLINKS Internet

resources are located throughout this chapter.

Reading Activity

Take a break after reading each section of this
chapter, and closely study the figures in the sec-
tion. Reread the figure captions, and, for each
one, write out a question that can be answered
by referring to the figure and its caption. Refer
to your list of figures and questions as you
review the concepts addressed in the chapter.

The transfer of information between these nerve cells
requires constant movement of substances across
their cell membranes.

Cells and Their

Environment

CHAPTER

4

4A

9A