AnswersPA Human Anatomy Physiology A 2026-2027 SMITH ICCatalysts

Catalysts — Unit test Answers

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1
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James is working with the lac operon of Escherichia coli (E. coli). He places the bacteria on a plate of growth media. Based on the current understanding of this operon, which hypothesis would be useful for James to test?

Question illustration
A
Addition of allolactose (inducer) to the bacterial growth media should increase the speed at which the bacteria metabolize the sugar lactose.
B
Removal of the RNA polymerase molecule should increase the amount of bacterial growth on the plate.
C
Decreasing the amount of allolactose (inducer) in the bacterial growth media should increase the rate of bacterial growth.
D
Increasing the rate at which RNA polymerase acts will inhibit bacterial growth.
2
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Which will increase the rate of a chemical reaction?

A
adding a catalyst
B
decreasing the pressure
C
decreasing the temperature
D
removing a catalyst
3

Which represents a strand of RNA bases?

A
CAAGGTCTC
B
AGGTTCACA
C
CAAGGUCUC
D
TGGAACTCA
4

The graph below compares the rates of reaction of a burning candle and an exploding firework.What can you conclude from the graph?

Question illustration
A
The reaction that causes a firework to explode requires less energy to start, and occurs more rapidly than the reaction that causes a candle to burn.
B
The reaction that causes a firework to explode requires less energy to start, and occurs less rapidly than the reaction that causes a candle to burn.
C
The reaction that causes a firework to explode requires more energy to start, and occurs less rapidly than the reaction that causes a candle to burn.
D
The reaction that causes a firework to explode requires more energy to start, and occurs more rapidly than the reaction that causes a candle to burn.
5

Which describes something that occurs during translation?

A
A DNA template is used to create an mRNA strand.
B
A tRNA template is used to create a DNA strand.
C
A tRNA template is used to create an mRNA strand.
D
An mRNA template is used to create an amino acid chain.
6

A forensic scientist is trying to find out the number of adenine bases in the DNA sample that he obtained from a crime scene.What can he assume about the number of adenine?

A
The number of adenine bases will be equal to the number of guanine bases.
B
The number of adenine bases will be equal to the total of all the other bases.
C
The number of adenine bases will be equal to the number of thymine bases.
D
The number of adenine bases will be half of the number of cytosine bases.
7

How many genes make up the human genome?

A
four: adenine, thymine, guanine, and cytosine
B
23 pairs of genes
C
20,000–25,000 genes
D
3 billion genes
8

Which of the following correctly organizes these genetic terms in order from smallest to largest?

A
chromosome, gene, nucleotide, DNA molecule
B
nucleotide, gene, DNA molecule, chromosome
C
DNA molecule, nucleotide, gene, chromosome
D
DNA molecule, nucleotide, chromosome, gene
9

Which is an arrangement of genes consisting of an operator, a promoter, and a repressor?

A
RNA polymerase
B
anticodon
C
codon
D
operon
10

Which of these is the primary site of protein synthesis?

A
mitochondria
B
cytoplasm
C
nucleus
D
ribosomes
11

Which best summarizes the process of protein synthesis?

A
RNA instructs DNA to make proteins.
B
DNA unzips, resulting in the formation of two protein molecules.
C
RNA moves the DNA code to the ribosomes for protein synthesis.
D
DNA makes proteins in the nucleus.
12

What was Friedrich Miescher's contribution to the discovery of the genetic code?

A
He created the first photograph of the structure of DNA.
B
He discovered how the DNA bases pair together.
C
He created the first accurate model of DNA's structure.
D
He extracted and observed DNA from white blood cells.
13

Which best matches a type of genetic material with its description?

A
Nucleotides form a helical structure that is called a gene.
B
Genes combine to form structures called nucleotides.
C
Chromosomes create genes.
D
DNA is located in the nucleus.
14

Which statement about enzymes is true?

A
An enzyme functions to decrease the rate of a chemical reaction.
B
Enzymes are proteins that function as catalysts in nonliving things.
C
Each enzyme can catalyze many different biochemical reactions.
D
Enzymes and substrates fit together like a lock and key.
15

Which statement best describes the relationship between activation energy and rate of reaction?

A
Increasing the activation energy can increase the rate of a reaction.
B
Reducing the activation energy can increase the rate of a reaction.
C
Increasing the reaction energy does not alter the rate of reaction.
D
Reducing the activation energy can decrease the rate of a reaction.
16

What must occur for protein translation to begin?

A
A water molecule must be added to the protein chain.
B
A peptide bond must form between subunits of mRNA.
C
The amino acid Cys must be picked up by tRNA.
D
The codon AUG must be identified.
17

What is a substrate?

A
a molecule that acts as a catalyst
B
a place on the enzyme where the reaction occurs
C
a place on the product where the enzyme fits
D
a reactant that is catalyzed by an enzyme
18

The diagram shows one step in the process of protein synthesis.Which step is shown?

Question illustration
A
transpiration
B
translocation
C
transcription
D
translation

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