Section: Coach Water — How Water Works
This section covers Chapter 1, Lessons 1.1 through 1.4.
Part A — Vocabulary (20 points, 2 points each)
Select the best answer for each question.
1. A polar molecule is:
A) A molecule that exists only at the Earth's poles B) A molecule with an uneven distribution of electrical charge — one end is slightly positive, the other slightly negative C) The same as an ion D) A molecule that does not dissolve in water
2. A hydrogen bond is:
A) A strong chemical bond between two hydrogen atoms B) A weak attraction between the slightly positive end of one polar molecule and the slightly negative end of another C) A type of ionic bond D) The bond inside a water molecule
3. Specific heat capacity is:
A) The amount of heat lost during sweating B) The amount of energy required to raise a substance's temperature by one degree; water's is unusually high C) A measure of body temperature D) The same as body mass
4. Osmosis is:
A) The active transport of sodium across a membrane B) The movement of water across a partially permeable membrane from a region of lower dissolved-particle concentration to higher C) The breakdown of cells D) The same as filtration
5. Intracellular fluid (ICF) is:
A) The water in the blood plasma B) The water inside the cells of the body, about two-thirds of total body water C) The fluid in the digestive tract D) The fluid between organs
6. A nephron is:
A) A type of kidney stone B) The microscopic functional unit of the kidney; each kidney has about one million C) A hormone of the kidney D) A blood vessel only
7. Antidiuretic hormone (ADH), also called vasopressin:
A) Stops the kidney from producing urine entirely B) Is released from the pituitary and signals the kidney to reabsorb more water, producing less but more concentrated urine C) Is produced in the kidney itself D) Has no role in hydration
8. An electrolyte is:
A) An electric battery B) A substance that, when dissolved in water, produces charged particles capable of conducting electricity C) A specific kind of vitamin D) A form of energy
9. Sodium (Na⁺) is:
A) The major intracellular cation B) The major extracellular cation; sets most of the osmotic concentration of blood C) An anion D) Found only in seawater
10. Osmoreceptors in the hypothalamus:
A) Detect changes in blood oxygen B) Are specialized neurons that detect changes in the dissolved-particle concentration of the blood and trigger thirst and ADH release C) Are located in the kidney D) Control body temperature
Part B — Concept Comprehension (20 points, 2 points each)
Select the best answer for each question.
11. A water molecule is made of which atoms?
A) One hydrogen and two oxygen B) Two hydrogen and one oxygen C) Two hydrogen and two oxygen D) One hydrogen and one oxygen
12. Approximately what percentage of an adolescent's body mass is water?
A) 20-30% B) 50-65% C) 80-90% D) Almost 100%
13. Which body water compartment is the largest?
A) Blood plasma B) Interstitial fluid C) Intracellular fluid D) Cerebrospinal fluid
14. In osmosis, water moves from regions of:
A) Higher to lower dissolved-particle concentration B) Lower to higher dissolved-particle concentration C) Cooler to warmer temperature D) Higher to lower oxygen content
15. The functional unit of the kidney is the:
A) Glomerulus B) Bladder C) Nephron D) Collecting duct
16. ADH causes the kidney to:
A) Reabsorb more water, producing less and more concentrated urine B) Reabsorb less water, producing more dilute urine C) Stop producing urine D) Filter blood faster
17. Which electrolyte is the major intracellular cation?
A) Sodium B) Potassium C) Chloride D) Calcium
18. Osmoreceptors in the hypothalamus detect changes in:
A) Blood temperature B) Blood oxygen C) The dissolved-particle concentration (osmolality) of the blood D) Heart rate
19. Approximately how much water does the average adolescent lose and gain each day?
A) 200-400 mL B) 0.5-1 L C) 2-2.5 L D) 8-10 L
20. Water is called the universal solvent because:
A) It is used in all laboratories B) It dissolves more substances than any other common liquid, which is why nearly every chemical reaction in your body happens in water C) It is universally available D) It has been certified by the United Nations
Part C — Application (30 points, 6 points each)
Write 2-4 complete sentences for each question. Show your reasoning.
21. Explain why water expands when it freezes and identify one biological or ecological consequence of this fact.
22. Describe the three main processes of the nephron (filtration, reabsorption, secretion). Approximately how much filtrate does the kidney produce per day, versus how much urine?
23. Identify the five major electrolytes and give one main role for each.
24. A friend insists that they "shouldn't wait to be thirsty" before drinking water. Based on what you have learned about osmotic thirst and the osmoreceptor system, write a response that engages with both the value and the limits of thirst as a signal.
25. Compare osmotic thirst and hypovolemic thirst. What does each system detect, and which is responsible for most everyday thirst?
Continue to the next section.