Why does phenylalanine accumulate in patients with phenylketonuria?
A. They lack an enzyme to break down phenylalanine.
B. They lack an enzyme to produce phenylalanine.
C. They produce too much phenylalanine.
D. They lack an inhibitor of an enzyme to break down phenylalanine.
E. They eat more phenylalanine than most people.
Answer: A. They lack an enzyme to break down phenylalanine.
You might also like to view...
Lions are heterotrophic carnivores living on the African savannah. They live in prides with
several females and a dominant male. Mating occurs in the summer. This describes the organism’s __________.
a. habitat b. niche c. food web d. carrying capacity
The first modern practitioner of taxonomy was ____
a. Ernst Mayr b. Jean Baptiste de Lamarck c. Alfred Russel Wallace d. Charles Darwin e. Carolus Linnaeus
Coenzyme Q (also known as ubiquinone or CoQ) is often found in lotions and moisturizers. Given
what you know about its role in cellular respiration, infer what it might be doing in these products.
a. It helps glycolysis proceed faster in the cytosol of skin cells. b. It absorbs dangerous free radicals (loose electrons) that can cause aging. c. It decreases the rate of metabolism and slows cellular growth. d. It is absorbed and used by cells with a high metabolism. e. It causes older cells to spontaneously die and regenerates new cells.
The enzyme carbonic anhydrase catalyzes the formation of carbonic acid from carbon dioxide and water. Imagine that you have two sealed tubes with carbon dioxide gas above a buffer containing water and carbon dioxide
One tube has carbonic anhydrase and the other does not. After 24 hours, both tubes are at equilibrium. Which statement below accurately describes the conditions in the tubes? A) The tube with carbonic anhydrase will have a lower concentration of carbon dioxide and a higher concentration of carbonic acid than the tube with any enzyme. B) The tube with carbonic anhydrase will have a higher concentration of carbon dioxide and a lower concentration of carbonic acid than the tube with any enzyme. C) The tubes will have equal concentrations of carbon dioxide and carbonic acid. D) The tube with carbonic anhydrase will have a higher concentration of carbonic acid than the tube with any enzyme, but the concentration of carbon dioxide will be the same in both tubes. E) It is not possible to determine the relative concentrations of the products and reactants without more information about carbonic anhydrase, such as the Km. What will be an ideal response?