Question

1. A catalyst enhances the reaction rate by: a. Adding energy to the reaction b. Increasing the activation energy required for the reaction c. Reducing the activation energy required for the reaction d. Improving binding of the product to the active site 2. Numerical answer: During aerobic respiration how many ATP molecules are produced by the oxidation of a single molecule of pyruvate? 3. The trace elements magnesium and zinc, which are required for bacterial growth, are typically used as: a. Catalysts b. Cofactors c. Enzyme inhibitors d. Coenzymes 4. Which of the following metabolic pathways consumes acetyl-CoA? a. Citric acid cycle b. Oxidative phosphorylation c. Beta oxidation d. Glycolysis 5. Formation of the nucleotide cytosine is a metabolic pathway that has 6 steps. The first enzyme in the pathway, aspartate transcarbanoylase (ATC), combines two amino acids to form the substrate for the 2nd step in the pathway. The final step of the pathway forms cytosine triphosphate (CTP), which is structurally unrelated to the two amino acid substrates required by the first enzyme. CTP inhibits the first enzyme in the pathway. CTP is most likely to be a: a. Irreversible inhibitor of ATC b. Competitive inhibitor of ATC C. Non-competitive inhibitor of ATC 6. The neurotoxin sarin is an irreversible inhibitor of acetylcholinesterase. What type of chemical bond does sarin form with the acetylcholinesterase? a. Covalent bond b. Hydrogen bond C. Metallic bond d. lonic bond

Answer 1

ANSWER 1 :-

1. Basically, an enzyme is a catalyst that speeds up a reaction. This in turn reduces the time required for a reaction to occur. There is basically an exergonic as well as endergonic reaction which becomes functional simultaneously to respond to the role and hence this catalyst itself is not involved in addition of energy and hence option 'A' is not appropriate.
2. If there is more interaction between the product and the active site, the reaction would specify an end. Active site is the site of an enzyme or catalyst where a substrate binds in order to initiate it's conversion to a product and hence option 'D' is not appropriate.
3. Activation energy in simple terms is the energy input to start a reaction. When the activation energy is more, there will be more requirement of energy to start a process and enzymes function by lowering this activation energy thereby speeding up the reaction. So, option 'B' is not correct and option 'C' is the most appropriate answer.