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Unit 2 Exam Review: Chapter 4 and 5

Chapter 4

  1. Imagine three cube shaped cells. Given the dimensions shown for each cube-shaped cell here, calculate the cell’s surface area, its volume and its surface-are-to-volume ratio.

10 µm / 20 µm / 100 µm
Surface Area
Volume
Surface Area to Volume Ratio
Reduced
  1. As the amount of toxin increases around the outside of the three cubed shaped cells above, which size of “cell” would be the first to have an enriched concentration of toxin in its center (core) region? Explain your answer using the surface area to volume ratio.
  1. Explain how prokaryotes carry out enzymatically-catalyzed biochemical conversions without the use of cellular organelles.
  1. Explain whether ribosomes are present only in eukaryotes, only in prokaryotes, or in both eukaryotes and prokaryotes.
  1. Discuss the argument that prokaryotes with flagella long proceeded the human “invention” of the wheel.
  1. Describe the structure and function of as many cellular organelles as you can in regard to the synthesis and secretion of protein signals.
  1. Specialized connections between adjacent cells in your heart hold them together closely so that blood does not leak out between the cells as the heart pumps. The pressure of pumping would blow apart adjacent cells were they not held tightly together by a second specialized connection. Furthermore, coordinated pumping activity of these cells relies on a third specialization between these cells. Describe how these three types of intercellular connections work together for the functioning of the heart.

Chapter 5

  1. Label these items: phospholipid, cholesterol, cytoskeleton, cytoplasm, integral protein, peripheral protein, and carbohydrate.

  1. The current model of the plasma membrane is referred to as the fluid mosaic model. Provide evidence that the membrane is “fluid” and describe the “mosaic” of this model.
  1. Explain how the structure of the phospholipid molecule is amphipathic and can form a membrane layer that is nonpolar in the middle and polar on the outsides.
  1. What are the two primary factors that influence membrane fluidity?
  1. Molecules that are amphipathic have both polar and nonpolar regions. For a large, amphipathic protein embedded in the phospholipid membrane, describe how this characteristic facilitates its placement in membranes. Draw a diagram of such an amphipathic protein embedded in the membrane below and label the polar and nonpolar regions.
  1. In this example, a drop of ink was placed into a bowl of gelatin. Explain how the ink diffused throughout the gel even though there were no currents to help move it around.
  1. Describe two differences between passive and active transport.
  1. Briefly explain how each of the three factors below can impact diffusion of solutes across membranes.
  1. Size of the diffusing solute –
  2. Temperature:
  1. Concentration gradient:
  1. Define each term and provide a description how that condition might affect a cell’s shape.
  1. Isotonic:
  1. Hypotonic:
  1. Hypertonic:
  1. Facilitated diffusion refers to a special type of transport: for example, the entry of glucose in to the muscles in your body. Is this type of trans-membrane movement considered to be an example of active transport or passive transport? Explain why.
  1. After several days without watering, plants tend to wilt. When the plant is watered, it will often return to its normal shape. Explain how cells are involved in the transition from wilted to normal.
  1. Complete the table below:

Simple Diffusion / Osmosis / Facilitated Diffusion / Active Transport
Cellular Energy required?
Driving force?
Membrane protein required?
Directional?
Specificity?
  1. Explain the sodium potassium pump briefly.
  1. Explain how phagocytosis and pinocytosis are similar and different.
  1. Describe each of the 3 major steps of cell signaling.
  1. Signal
  1. Receptor
  1. Response
  1. Different receptor proteins for different signals are found in the cytoplasm or on the membrane of the cell. Give one example of each and discuss the properties of the ligand that activates this receptor.
  1. Intracellular receptor protein
  1. Membrane bound receptor protein
  1. If a cell had no proteins in its membrane, will it be able to respond to any environmentally stimuli? Explain.
  1. Here is a diagram of caffeine. Caffeine acts by binding with a receptor on the cell surface? Why doesn’t it enter the cell?

Radjewski 2013 AP Biology