Question

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start quiz - ch. 4

1. which of the following describes an enzyme?

a. a catalyst for a chemical reaction.
b. a compound that is changed into a product during a chemical reaction.
c. the end product(s) of a chemical reaction.
d. a compound that stores energy within its chemical bonds.

1. atp molecules provide energy for cellular activities by _.

a. lowering the activation energy needed to begin a chemical reaction
b. releasing the terminal phosphate group and the energy associated with the bond
c. serving as a coenzyme, binding to the enzyme to convert it to its active form
d. triggering reactions to break down glucose; this releases energy to fuel the cell

1. what is an important mechanism that controls metabolic pathways?

a. genetic control
b. negative feedback
c. positive feedback
d. amplification

1. name the process by which a mrna strand is built using a dna sequence as a template.

a. transcription
b. replication
c. dehydration synthesis
d. translation

1. what is the function of ribosomes?

a. production of the majority of cellular atp
b. detoxification of the cytoplasm
c. lipid and carbohydrate synthesis
d. protein synthesis

Explanation:

1. Enzymes are biological catalysts that speed - up chemical reactions.
2. ATP provides energy by releasing the terminal phosphate group and its associated energy.
3. Negative feedback is a common mechanism to control metabolic pathways, as it helps maintain homeostasis by inhibiting the pathway when the product accumulates.
4. Transcription is the process of synthesizing mRNA from a DNA template.
5. Ribosomes are the sites of protein synthesis in the cell.

Answer:

1. a. A catalyst for a chemical reaction.
2. b. releasing the terminal phosphate group and the energy associated with the bond
3. b. Negative feedback
4. a. Transcription
5. d. Protein Synthesis