AP Biology Free-Response Week 4 (August 25, 2008)
Use the tips for answering free response questions found on the FSHS AP Biology website. Each question should be answered in essay form with complete sentences and labeled clearly. After completing answer, use a highlighter to emphasize main points and clarifying details of your response. Your free response questions will comprise a major test grade each nine weeks.
1. Cells transport substance across their membranes. Choose three of the following four types of cellular transport.
a. Osmosis
b. Active transport
c. Facilitated diffusion
d. Endocytosis/ Exocytosis
For each of the three transport types you choose:
a. Describe the transport process and explain how the organization of cell membranes functions in the movement of specific molecules across the membrane; and
b. Explain the significance of each type of transport to a specific cell (you may use different cell types as examples.)
2. Imagine a spherical cell with a radius of 10 μm. Show your calculations. What is the cell’s surface area in μm2 ? Its volume in μm3? What is the ratio of surface area to volume for this cell? Now do the same calculations for a second cell, this one with a radius of 20 μm. Compare the surface-to-volume ratio of the two cells. How is this comparison significant to the functioning of cells? (Note: For a sphere of radius r, surface area = 4πr² and volume = 4/3πr³. Remember π is 3.14.)
3. The cells of plant seeds store oils in the form of droplets enclosed by membranes. Unlike typical biological membranes, this oil droplet membrane consists of a single layer of phospholipids rather than a bilayer. Draw a model for a membrane around such an oil droplet. Explain why this membrane around such an oil droplet. Explain why this arrangement is more stable than a bilayer of phospholipids.
4. Cilia are found on cells in almost every organ of the human body, and the malfunction of cilia is involved in several human disorders. During embryological development , for examples, cilia generate a leftward flow of fluid that initiates the left-right organization of the body organs. Some individuals with primary ciliary dyskinesia exhibit situs inversus, in which internal organs such as the heart are on the wrong side of the body. Explain why this reversed arrangement may be a sympton of PCD.
5. Prokaryotes are found throughout the biosphere. Answer two of the following.
a. Provide three examples of adaptations found in various prokaryotes. Explain how these three adaptations have ensured the success of prokaryotes.
b. Discuss how prokaryotes early in Earth’s history altered environments on Earth.
c. Discuss three ways in which prokaryotes continue to have ecological impact today.