13. Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through ________.
(A) plasmodesmata
(B) tight junctions
(C) desmosomes
(D) gap junctions

9. Which structure below is independent of the endomembrane system? (A) nuclear envelope (B) chloroplast (C) Golgi apparatus (D) endoplasmic reticulum

10. Which of the following organelles produces and modifies polysaccharides that will be secreted? (A) lysosome (B) mitochondrion (C) Golgi apparatus (D) peroxisome

11. Thylakoids, DNA, and ribosomes are all components found in _______. (A) chloroplasts (B) mitochondria (C) lysosomes (D) nuclei

12. The evolution of eukaryotic cells most likely involved _________. (A) endosymbiosis of an oxygen-using bacterium in a larger bacterial host cell - the endosymbiont evolved into chloroplasts (B) endosymbiosis of a photosynthetic archaeal cell in a larger bacterial host cell to escape toxic oxygen - the anaerobic archaea evolved into chloroplasts (C) endosymbiosis of an oxygen-using bacterium in a larger bacterial host cell - the endosymbiont evolved into mitochondria (D) evolution of an endomembrane system and subsequent evolution of mitochondria from a portion of the smooth endoplasmic reticulum

14. Which of the following structures form cytoplasmic channels that connect adjacent plant cells through the cell walls? (A) desmosomes (B) gap junctions (C) plasmodesmata (D) tight junctions

15. The cell walls of bacteria, fungi, and plant cells, and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following characteristics are common to all of these extracellular structures? (A) They must block water and small molecules to regulate the exchange of matter and energy with their environment. (B) They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume. (C) They are constructed of materials that are synthesized in the cytoplasm and then transported out of the cell for assembly. (D) They are composed of a mixture of lipids and nucleotides.

16. Cilia and flagella bend because of _______. (A) conformational changes in ATP that thrust microtubules laterally (B) a motor protein called radial spokes (C) contraction by myosin (D) a motor protein called dynein

17. Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to _______. (A) form cleavage furrows during cell division (B) migrate by amoeboid movement (C) separate chromosomes during cell division (D) maintain the shape of the nucleus

18. Suppose a cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from _______. (A) a bacterium, but not a eukaryote (B) an animal, but not a plant (C) nearly any eukaryotic organism (D) a plant, but not an animal

19. Which cell would be best for studying lysosomes? (A) muscle cells (B) nerve cells (C) endocrine cells (D) phagocytic white blood cells