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327 A Pelid . 1 Comparison of Specifics in the IB and AP Course Outlines and Corresponding Lamination Questions The International BaccaLaureate (IB) program has a detailed course outline and prescription for the depth of teaching. While the Advanced PLacment (AP) program may demand the same depth or more through its assessment, it Is not clearly evident in the course outline. Example membrane architecture: IB specifically requires teaching of the fluid mosaic model: phospho- lipid bilayer, cholesterol, glycoproteins, and intrinsic and extrinsic proteins. The course must include how amphipathic phospholipids maintain mem- brane structure, but nothing about what the intrinsic proteins are (e.g., re- ceptors for cell signaling). AP instructs the teacher to cover the "current model of the molecular architecture of membranes." Example Ced membrane transport: IB specifically requires defining diffusion and osmosis and describ- ing passive transport, including osmosis (permeability, non- and partial per- meability). IB also mandates that students be able to describe active trans- port across membranes, including the roles of protein carriers, adenosine triphosphate (ATP), and a concentration gradient. Students are expected to know about carrier-assisted transport and the importance of favorable con- centration gradients for facilitated transport; to predict conditions for active transport with examples; to understand membrane pumps without biochemical

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328 . CONTENT PANEL REPORT details; and to compare endocytosis and exocytosis, phagocytosis and pi- nocytosis, and vesicle-mediated transport. Students must also be able to explain the dynamic relationships among the nuclear membrane, rough en- doplasmic reticulum Golgi apparatus, and cell surface membrane. They must be able to describe ways in which vesicles are used to transport materials within a cell and to the cell surface, as well as membrane proteins and their positions within membranes. (Students can use a series of diagrams to dem- onstrate structure relationships and how materials are moved. They must know about channel proteins and the flow of materials through channels or vesicles. Knowledge of the chemical nature of materials is not required. Mention of pores and the fact that some intrinsic proteins are anchored is also expected.) Students should be able to outline the functions of mem- brane proteins as antibody recognition sites, hormone binding sites, cata- lysts for biochemical reactions, and sites of electron carriers. (Again, nothing is included about the most important class- receptors for cell signaling- except in the oblique reference to hormone binding sites.) AP requires that students be able to detail how the structural organi- zation of membranes provides for transport and recognition and the mecha- nisms by which substances cross membranes. They must also address how variations in the structure account for functional differences among mem- branes. Questions on the AP and IB exams are comparable in the degree of detail expected. Examples AP exam questions related to cell membranes (May 1999 exam, series of questions based on an idustrationg: 17. Membranes are components of all of the following except a (A) microtubule, (B) nucleus, (C) Golgi apparatus, (D) mitochondrion, (E) lyso- some. 31. All of the following are typical components of the plasma mem- brane of a eukaryotic cell except (A) glycoproteins, (B) cytochromes, (C) cholesterol, (D) phospholipids, (E) integral proteins. 61. Which of the following cellular processes is coupled with the hy- drolysis of ATP? (A) Facilitated diffusion, (B) Active transport, (C) Chemiosmosis, (D) Osmosis, (E) Na+ influx into a nerve cell. Questions 11~116 refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3 percent starch and 3 percent glucose and placed in a beaker of distilled water. After 3 hours, glucose can be detected in the water outside of the dialysis-tubing bag, but starch cannot.

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BIOLOGY ,lK ~ Distilled water Dialysis-tubing bag with 3% starch and 3% glucose 114. From the initial conditions and results described, which of the fol- lowing is a logical conclusion? (A) The initial concentration of glucose in the bag is higher than the initial concentration of starch in the bag. (B) The pores of the bag are larger than the glucose molecules but smaller than the starch molecules. (C) The bag is not selectively permeable. (D) A net move- ment of water into the beaker has occurred. (E) The molarity of the solution in the bag and the molarity of the solution in the surrounding beaker are the same. . 115. Which of the following best describes the conditions expected after 24 hours? (A) The bag will contain more water than it did in the original condition. (B) The contents of the bag will have the same osmotic concen- tration as the surrounding solution. (C) Water potential in the bag will be greater than water potential in the surrounding solution. (D) Starch mol- ecules will continue to pass through the bag. (E) A glucose test on the solution in the bag will be negative. 116. If, instead of the bag, a potato slice were placed in a beaker of distilled water, which of the following would be true of the potato slice? (A) It would gain mass. (B) It would neither gain nor lose mass. (C) It would absorb solutes from the surrounding liquid. (D) It would lose water until water potential inside the cells is equal to zero. (E) The cells of the potato would increase their metabolic activity. Essay: Communication occurs among cells in a multicellular organism. Choose three of the following examples of cell-to-cell communication, and for each example, describe the communication that occurs and the types of responses that result from the communication. Communication between two plant cells. Communication between two immune cells. Communication either between a neuron and another neuron or be- tween a neuron and a muscle cell. get cell. Communication between a specific endocrine gland cell and its tar- 329

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330 . CONTENT PANEL REPORT Example~IB questions related to cell membranes: [November 1999 Paper One (multiple choice), #21: 2. The cells of plant roots can take up ions from the soil against the concentration gradient. What is the process used? (A) Osmosis. (B) Passive transport. (C) Diffusion. (E) Carrier-assisted transport. [November 1999 Paper Two]: Part A (Extended Response) #2 A. Draw the structure of a nephron. B. Iden- tify where most active transport occurs and identify one specific location where active transport occurs in plants. C. Define water potential. D. Explain the process of water uptake in roots by osmosis. E. List three abiotic factors which affect the rate of transpiration in a typical terrestrial mesophytic plant. Part B (Extended Response) A. List three functions of lipids. B. Outline the production of ATP by chemiosmosis in the mitrochondrion. C. Explain the process of muscle contraction.