5 Steps to a 5 AP Biology, 2014-2015 Edition

56 ❯ STEP 4. Review the Knowledge You Need to Score High

5. Endocytosis:a process in which substances are brought into cells by the enclosure of
   the substance into a membrane-created vesicle that surrounds the substance and escorts
   it into the cell (Figure 6.2). This process is used by immune cells called phagocytesto
   engulf and eliminate foreign invaders.


6. Exocytosis:a process in which substances are exported out of the cell (the reverse of
   endocytosis). A vesicle again escorts the substance to the plasma membrane, causes it
   to fuse with the membrane, and ejects the contents of the substance outside the cell
   (Figure 6.2). In exocytosis, the vesicle functions like the trash chute of the cell.

Review Questions

Endocytosis

Exocytosis

Figure 6.2 Endocytosis and exocytosis.

For questions 1–4, please use the following answer
choices:

A. Cell wall

B. Mitochondrion

C. Ribosome

D. Lysosome

E. Golgi apparatus

1. This organelle is present in plant cells, but not
   animal cells.
   2. Absence of enzymes from this organelle can lead
   to storage diseases such as Tay-Sachs disease.
   3. This organelle is the host for the Krebs cycle and
   oxidative phosphorylation of respiration.
   4. This organelle is synthesized in the nucleolus of
   the cell.