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UNC-Chapel Hill BIOL 252 - Homework 4 KEY

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Homework 4 (Lessons 9-11) Striated muscle tissue is only capable of voluntary movement. ( ) True (X) False Which of the following drugs would be the best therapeutic option for a patient who is having frequent skeletal muscle spasms (or contractions)? ( ) A drug that inhibits acetylcholinesterase (X) A drug that inhibits ligand-gated acetylcholine receptors ( ) A drug that activates voltage-gated Ca2+ channels ( ) A drug that inhibits non-selective cation channels If an individual has a genetic defect in a crucial enzyme involved in the Cori Cycle that makes the enzyme non-functional, which of the following is a potential negative consequence? (X) Reduced blood pH ( ) Hyperglycemia ( ) Elevated ATP generation in the mitochondria ( ) Reduced creatine kinase activity Which of the following is NOT found in the sarcolemma of a skeletal muscle fiber? (Select all that apply) [X] Voltage-gated Ca2+ channel [ ] Voltage-gated Na+ channel [ ] Voltage-gated K+ channel [ ] Na+/K+ ATPase Fibroblast growth factor receptor 3 (FGFR3) signaling has been shown to prohibit the proliferation of chondrocytes. An individual with a gain of function mutation in FGFR3, thus making FGFR3 constitutively active, is likely to suffer from which of the following? ( ) Osteoporosis ( ) Gigantism (X) Dwarfism ( ) AnemiaWhich of the following statements are TRUE? 1) Osteoblasts produce collagen and ground substance in the bone 2) Osteogenic cells are able to differentiate into either osteoblasts or osteoclasts. 3) Osteoclasts resorb bone by secreting enzymes and H+ ions ( ) 1, 2 and 3 ( ) 1 and 2 (X) 1 and 3 ( ) 2 and 3 Susan is a 55-year old post-menopausal woman who has been shown to have low bone density, putting her at risk of osteoporosis. Which of the following treatments and/or activities would you recommend for Susan? (select all that apply) [X] Take birth control (or synthetic estrogen) [X] Include strength training in her fitness routine [X] Take an over-the-counter vitamin D supplement Which of the following supports the sliding filament theory of muscle contraction? ( ) No change in the distance between Z lines during contraction (X) A decreased width of the H band during contraction ( ) Increased width of the I band during contraction ( ) Decreased width of the A band during contraction Which of the following is most likely to result in a fused tetanus? ( ) Physical inactivity (X) “Charlie horse” cramp (or muscle spasm) ( ) Repeated reps of bicep curls in the gym ( ) Running a 5k at a moderate pace (11 min/mile) Long bones can have more than one ossification centers. (X) True ( ) False The central canal of compact bone serves as channels for osteocyte processes to interact and sense whether bone should be resorbed or deposited. ( ) True (X) FalseA muscle contraction that involves lengthening of the muscle while holding a 20 lb dumbbell requires greater tension than a contraction that involves shortening of the muscle holding the same dumbbell. (X) True ( ) False Elastic connective tissue is found in large blood vessels of the body. What would occur in these vessels if the elastic fibers were replaced with collagen fibers? ( ) The vessels would not be able to resist tension (X) The vessels would lose their ability to stretch ( ) The vessels would not be able to resist pressure ( ) The vessels would increase in size What happens to bone tissue when osteoclasts become more active than osteoblasts? (X) The bone tissue will be broken down and become weaker ( ) The bone tissue will no longer go through bone resorption ( ) The bone tissue will remodel at a constant rate ( ) The bone tissue will become denser and stronger If actin filaments were in capable of sliding past the myosin filaments... (X) Contraction would not occur, and tension would not be generated ( ) A contraction would occur, but no tension would be generated ( ) No contraction would occur, but tension would be generated ( ) A contraction would occur and tension would be


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