I\'ve got a practice test that I\'d like to check my answers with. Please help o

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I've got a practice test that I'd like to check my answers with. Please help out!

(Multiple choice are 2 points each) 1. Contractions in muscles are activated as a result of 2+ A) a decrease in the Ca concentration in cytoplasm B) a decrease in the Ca concentration in nucleus C) an increase in the Ca concentration in cytoplasm D) an increase in the Ca concentration in nucleus E) nothing related to Ca concentration 2+ 2+ 2. The Bohr effect describes the observed increased in O2 affinity by Hb when A) O2 concentration decreases ) BPG concentration increases C) BPG concentration decreases D) pH decreases E) pH increases 3. There are five different classes of antibodies produced by our immune system. Among them IgG is one type having a molecular mass of approximately 150 kDa. How many subunits the IgG have? A) 1 heavy chain and 1 light chain C) 2 heavy chains and 2 light chains D) 2 heavy chains, 2 light chains, and a J chain E) 4 heavy chains and 4 light chains B) 1 heavy chain, 1 light chain and a J chain 4. Glucose, an aldohexose has_stereoisomer(s) A) 1 B) 2 C)4 D) 8 E) 16 5. Ribulose, a ketopentose, has A) 1 B) 2 C)4 D) 8 E) 16 stereoisomer(s) 6. Actin and myosin are the two main proteins participating in muscular contractions. When a muscle contracts A) actin filaments are pushed towards the Z disk by myosin B) actin filaments are pulled towards the M disk by myosin C) myosin is pushed towards Z disk by actin D) myosin is pulled towards M disk by actin E) None of the answers above are correct. 7. Carbonic anhydrase catalyzes A) bicarbonate hydration, resulting in the formation of carbonic acid. B) carbamates hydrolysis with associated proton consumption C) carbamates formation with the associated proton release D) carbon dioxide reduction with associated consumption of protons. E) carbon dioxide hydration, forming bicarbonate and protons. 8. Which of the following statements is true? A) Fatty acids with more than 18 carbons are the most common. B) Synthesis of fatty acids occurs in 2 carbon units. C) Fatty acids with conjugated double bonds very common in plants. D) In higher plants and animals, C12 and C14 species predominate -. Hemoglobin is composed of 4 subunits that are arranged in a particular symmetry, what is the arrangement of symmetry? F) Tetrahedral symmetry 10. An alcohol can react with an aldehyde to form a (an) which can react with another alcohol to form a (an) A) hemiketal, ketal B) hemiacetal, acet E) lactone, lactam C) lactam, acta D) glycoside, glycotide

Explanation / Answer

1) An increase in Ca2+ concentration in the cytoplasm - When a muscle is about to contract, the calcium gated channel open and calcium ions rush in. Once the calcium ion levels fall in cytoplasm, the muscle begins to relax.

2) pH increases - Bohr effect describes that the binding affinity of hemoglobin for oxygen reduces at lower pH and high concentration of CO2. Bohr effect does not include the effects of BPG. Accumulation of BPG in hemoglobin decreases the affinity of hemoglobin for oxygen.

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