1. A person s blood glucose level is affected by the sugars contained in food. Blood glucose levels are controlled by the hormone insulin via a homeostatic feedback mechanism. A person eats a meal containing a large amount of complex carbohydrates. Which graph shows how a normal person s blood glucose level will most likely change over the next two hours? (A) Rationale: This answer suggests the student understands that blood glucose levels will initially rise due to the digestion of the carbohydrates in the meal and then gradually decline as insulin is produced in order to maintain homeostasis via a feedback mechanism. Page 1 of 8
(B) This answer suggests the student may understand that blood glucose levels will rise, but does not understand that blood glucose will rapidly rise as carbohydrates are digested and then decline as insulin is produced by a homeostatic feedback mechanism to bring levels back into a normal range. (C) Page 2 of 8
This answer suggests the student may understand that blood glucose levels will initially rise and then decline as insulin is released, but does not understand that blood glucose levels will not rise again spontaneously. (D) This answer suggests the student may understand that blood glucose levels will rise initially as carbohydrates are digested, but does not understand that insulin will be released as soon as blood glucose levels increase, which will result in blood glucose peaking momentarily and then gradually returning to within a normal range, rather than returning to normal levels immediately. Aligned to: LO 2.9 CA 2.9: Represent & Model Matter Exchange Page 3 of 8
2. The diagram below shows some of the ways in which nitrogen cycles through an ecosystem. Arrows X and Y represent processes that convert nitrogen from one form to another. Which statement describes the two processes arrows X and Y most likely represent? (A) Arrow X represents the production of waste products by animals, and arrow Y represents the uptake of atmospheric nitrogen by plants. This answer suggests the student may understand that an animal s waste product may contain ammonia, but does not understand that bacteria break down the ammonia in an animal s urine into ammonium, that arrow X represents bacteria breaking down organic matter into ammonium, and that arrow Y represents soil bacteria converting atmospheric nitrogen gas into ammonia. (B) Arrow X represents the conversion of ammonia into ammonium, and arrow Y represents bacteria oxidizing nitrogen gas. This answer suggests the student may understand that ammonia is converted into ammonium in the nitrogen cycle, but does not understand that arrow X represents bacteria breaking down organic matter into ammonium (not ammonia), and that arrow Y represents soil bacteria converting atmospheric nitrogen gas into ammonia (reduction of nitrogen gas). (C) Arrow X represents the breakdown of organic matter by bacteria, and arrow Y represents soil bacteria converting atmospheric nitrogen gas to ammonia. Page 4 of 8
Rationale: This answer suggests the student understands that arrow X represents bacteria breaking down (decomposing) organic matter into ammonium, and that arrow Y represents soil bacteria converting atmospheric nitrogen gas into ammonia. (D) Arrow X represents the uptake of nitrogen oxide by soil bacteria, and arrow Y represents soil bacteria converting nitrogen gas into biomass. This answer suggests the student may understand that nitrogen oxide exists in the soil, but does not understand that animals and plants release ammonia and not nitrogen oxide as waste, that arrow X represents bacteria breaking down (decomposing) organic matter into ammonium, and arrow Y represents soil bacteria converting atmospheric nitrogen gas into ammonia. Aligned to: LO 2.9 CA 2.9: Represent & Model Matter Exchange 3. Approximately 99% of the calcium in the human body is stored in bones. Calcium is absorbed from food through the small intestine during digestion. The kidneys may excrete or reabsorb small amounts of calcium to maintain homeostasis. The recommended daily intake of calcium for people aged 19 50 is 1000 milligrams a day. The table below shows the total calcium intake for a 25-year-old female each day for 14 days. Which statement describes the most likely physiological response the female s body will experience during the 14 days? (A) More calcium is excreted by the kidneys during days 1 through 7, and more calcium is deposited in the bones during days 8 through 14. Page 5 of 8
This answer suggests the student may understand that excess calcium is excreted by the kidneys and stored in the bones, but does not understand that the kidneys will reabsorb calcium to maintain homeostasis during the first 7 days due to low dietary calcium intake levels. (B) Less calcium is reabsorbed by the kidneys during days 1 through 7, and more calcium is absorbed through the small intestine during days 8 through 14. This answer suggests the student may understand that the kidneys and the small intestines will reabsorb calcium when levels are low, but does not understand that the kidneys will reabsorb calcium in the first 7 days since dietary calcium intake levels are low, and that the small intestine will not absorb more calcium during days 8 through 14 because dietary calcium intake levels are in excess of what is needed to maintain homeostasis. (C) Less calcium is released from the bones during days 1 through 7, and more calcium is deposited in the bones during days 8 through 14. This answer suggests the student may understand that excess calcium is deposited in the bones when calcium levels are high, but does not understand that the bones will release calcium into the blood during the first 7 days because dietary intake levels of calcium are too low to maintain homeostasis. (D) More calcium is released from the bones during days 1 through 7, and more calcium is excreted by the kidneys during days 8 through 14. Rationale: This answer suggests the student understands that calcium is released from the bones into the blood during the first 7 days because dietary calcium intake is not adequate to maintain homeostasis, and that excess calcium is excreted by the kidneys during days 8 through 14, when calcium levels are in excess of what is needed to maintain homeostasis. Aligned to: LO 2.9 CA 2.9: Represent & Model Matter Exchange Page 6 of 8
4. The pancreas produces two hormones in response to changes in blood glucose levels. Insulin is produced when blood glucose levels are high to encourage body cells to take up and store excess glucose. Glucagon is produced when blood glucose levels are low and causes the liver to release stored glucose into the bloodstream. A person undergoes a blood test at the end of a 12-hour fast during which only water is consumed. Which statement predicts the most likely result of the person s blood test? (A) Glucagon levels will be elevated and insulin levels will be normal as the body releases stored glucose in an attempt to raise the available glucose in the blood. Rationale: This answer suggests the student understands that glucagon levels will be elevated and insulin levels will be normal as the body stimulates the release of stored glucose into the blood to supply cells with enough glucose to maintain normal function during a short 12-hour fast. (B) Glucagon levels will be normal and insulin levels will be elevated because the body is trying to control the release and uptake of the limited amount of glucose in the blood. This answer suggests the student may understand that glucagon and insulin play a role in the regulation of glucose in the blood and the uptake of glucose by cells, but does not understand that glucagon levels would be elevated to release stored glucose into the blood and that insulin levels will be normal to encourage cells to continue to take in sugar. (C) Glucagon levels will be normal and insulin levels will be elevated as the body prepares for an extended period of starvation. This answer suggests the student may understand that the body has lower blood glucose during a fast, but does not understand that glucagon levels would be elevated to encourage the release of stored glucose and that insulin levels would be normal in order to raise blood sugar levels and encourage cells to take up enough glucose for normal cell function, or that the body does not release hormones in advance of what may occur in the future. (D) Glucagon levels will be elevated and insulin levels will be normal because the body is trying to minimize the rate at which starved cells take up glucose from the blood. Page 7 of 8
This answer suggests the student may understand that glucagon levels would be elevated and insulin levels would be normal, but does not understand that glucagon levels are elevated to increase the release of stored glucose into the bloodstream and that normal levels of insulin encourage cells to take up glucose from the bloodstream to maintain normal cell function, but not at a minimum rate. Aligned to: LO 2.9 CA 2.9: Represent & Model Matter Exchange Page 8 of 8