ANSWERS TO REVIEW QUESTIONS FOR THE DAY

1. Which structure includes all of the others?
1. nucleolus
2. nucleus
3. chromosomes
4. genes

2. Most cell membranes are composed principally of
1. DNA and ATP
2. proteins and lipids
3. chitin and starch
4. nucleotides and amino acids

3. Which structure is usually present only in animal cells?
1. vacuole
2. cell wall
3. nucleus
4. centriole

4. Normally, in the process of osmosis, the net flow of water molecules into or out of the cell depends upon differences in the
1. concentration of water molecules inside and outside the cell
2. concentration of enzymes on either side of the cell membrane
3. rate of molecular motion on either side of the cell membrane
4. rate of movement of insoluble molecules inside the cell

5. Sodium ions are "pumped" from a region of lower concentration to a region of higher             concentration in the nerve cells of humans. This process is an example of
              A. diffusion

              B. passive transport

              C. osmosis

               D. active transport

6. An organelle differs from an organ in that an organelle

          A. is a substructure of a cell

          B. contains one specific type of tissue

          C. is larger than an organ

          D. cannot be stained