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Chapter 3

16 November, 2015 - 17:52
  1. Figure 3.7 Plant cells have plasmodesmata, a cell wall, a large central vacuole, chloroplasts, and plastids. Animal cells have lysosomes and centrosomes.
  2. Figure 3.13 Because that face receives chemicals from the ER, which is toward the center of the cell.
  3. Figure 3.22 No, it must have been hypotonic, as a hypotonic solution would cause water to enter the cells, thereby making them burst.
  4. C
  5. B
  6. D
  7. A
  8. D
  9. A
  10. A
  11. D
  12. C
  1. D
  2. The advantages of light microscopes are that they are easily obtained, and the light beam does not kill the cells. However, typical light microscopes are somewhat limited in the amount of detail that they can reveal. Electron microscopes are ideal because you can view intricate details, but they are bulky and costly, and preparation for the microscopic examination kills the specimen. Transmission electron microscopes are designed to examine the internal structures of a cell, whereas a scanning electron microscope only allows visualization of the surface of a structure.
  3. Prokaryotic cells are surrounded by a plasma membrane and have DNA, cytoplasm, and ribosomes, like eukaryotic cells. They also have cell walls and may have a cell capsule. Prokaryotes have a single large chromosome that is not surrounded by a nuclear membrane. Prokaryotes may have flagella or motility, pili for conjugation, and fimbriae for adhesion to surfaces.
  4. “Form follows function” refers to the idea that the function of a body part dictates the form of that body part. As an example, organisms like birds or fish that fly or swim quickly through the air or water have streamlined bodies that reduce drag. At the level of the cell, in tissues involved in secretory functions, such as the salivary glands, the cells have abundant Golgi.
  5. The fluidity of the cell membrane is necessary for the operation of some enzymes and transport mechanisms within the membrane.
  6. Water moves through a semipermeable membrane in osmosis because there is a concentration gradient across the membrane of solute and solvent. The solute cannot effectively move to balance the concentration on both sides of the membrane, so water moves to achieve this balance.
  7. The cell harvests energy from ATP produced by its own metabolism to power active transport processes, such as pumps.