GED Science : DNA, RNA, and Proteins

Study concepts, example questions & explanations for GED Science

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Example Questions

Example Question #51 : Biology And Life Sciences

Which of the following is NOT common to both DNA and RNA?

Possible Answers:

Both use adenine as a nitrogenous base

Both are composed of nucleotides

Both have a sugar phosphate backbone

Both use thymine as a nitrogenous base

Correct answer:

Both use thymine as a nitrogenous base

Explanation:

RNA and DNA have many similarities in structure. They are both nucleic acids, meaning they are polymers of nucleotides; the structure of both DNA and RNA is made by bonding many nucleotide units into a long polymer chain. These chains are created by bonding in the sugar phosphate backbone. Each nucleotide contains a sugar, a phosphate, and a nitrogenous base. When the sugars and phosphates bind, nucleotides are strung together to create the nucleic acid chain.

There are two key structural differences between DNA and RNA. The first is the identity of the sugar used in the sugar phosphate backbone. DNA uses deoxyribose, while RNA uses ribose. Both are pentose sugars, meaning they have five carbons, but the 2' carbon in RNA has a hydroxyl group that is absent in DNA. The second major difference is the identity of the nitrogenous bases used to code genetic information. DNA uses cytosine, guanine, adenine, and thymine. RNA uses cytosine, guanine, adenine, and uracil. Thymine will not be found in RNA and uracil will not be found in DNA.

Example Question #52 : Biology And Life Sciences

What does it mean to say that DNA replication is semiconservative?

Possible Answers:

Only one DNA strand is replicated at a time

DNA replication occurs spontaneously in aqueous solutions

Daughter DNA molecules have one old strand from the parent molecule and one newly synthesized strand

DNA replication has a leading strand, which is synthesized continuously, and a lagging strand, which is synthesized in fragments

Correct answer:

Daughter DNA molecules have one old strand from the parent molecule and one newly synthesized strand

Explanation:

DNA replication is defined as being semiconservative. This statement means that when a DNA molecule undergoes replication, the DNA helix unwinds and each strand serves as a template for the new strand to be created. Once a new DNA molecule has been created, it is composed of both an old strand (template), and the newly created strand, thus making a new double helix.

While the answer choice about leading and lagging strands is a true statement with regard to DNA replication, it is unrelated to the semiconservative nature of the process.

Example Question #1 : Dna And Dna Repair

During DNA replication, primase creates a(n) __________ which serves as a site for __________ to attach and begin strand synthesis.

Possible Answers:

RNA primer . . . DNA polymerase I

RNA primer . . . DNA polymerase III

DNA primer . . . RNA polymerase

DNA primer . . . DNA polymerase III

Correct answer:

RNA primer . . . DNA polymerase III

Explanation:

During DNA replication, DNA polymerase III needs a site of attachment in order to begin DNA strand synthesis. This template is provided by primase, which lays down an RNA primer for DNA polymerase III to attach.

RNA polymerase is not involved in DNA replication (it is involved in translation), and DNA polymerase I is used to replace the RNA primers with DNA nucleotides.

Example Question #51 : Biology And Life Sciences

Which of the following actions is performed by proteins?

Possible Answers:

Creating the structure of the cellular membrane

Serving as biological catalysts

Providing energy for the body

Storing genetic information

Correct answer:

Serving as biological catalysts

Explanation:

Proteins have a variety of functions in the body, one of which is acting as biological catalysts. These specialized proteins are called enzymes and are used to facilitate all types of chemical reactions in organisms.

Storing genetic information is accomplished by nucleic acids, and energy is provided by carbohydrates. Lipids (or phospholipids to be specific) help create the plasma membrane structure.

Example Question #51 : Biology And Life Sciences

Which of the following RNA molecules brings amino acids to the ribosomal complex during translation?

Possible Answers:

mRNA

tRNA

rRNA

aRNA

Correct answer:

tRNA

Explanation:

The process of translation involves a variety of RNA molecules, all with specific roles necessary in order to create the functional protein. mRNA (messenger RNA) is the product of DNA transcription and provides the template that the ribosome will read. rRNA (ribosomal RNA) helps create the functional ribosomal complex. tRNA (transfer RNA) brings individual amino acids to the ribosome in order to lengthen the growing polypeptide chain.

Example Question #1 : Dna, Rna, And Proteins

What is true about the genetic code?

Possible Answers:

One codon can code for multiple amino acids

There are only 20 functional codons, due to the 20 amino acids found in organisms

Codons are composed of 4 nucleotide segments

Multiple codons can code for the same amino acid

Correct answer:

Multiple codons can code for the same amino acid

Explanation:

The genetic code is defined as being both unambiguous and degenerative. The term degenerative means that an amino acid can have multiple codons that code for it. For example, both UCC and UCG code for the amino acid serine. The term unambiguous means that a codon will always code for only one amino acid. For example, UCC will only ever code for serine; it cannot generate any other amino acid.

Each codon has three nitrogenous base units. Since there are four possible bases, there are 64 3-base combinations (64 possible codons). The degenerative nature of the code allow each and every combination to code for an amino acid.

Example Question #71 : Ged Science

Which of the following depicts the central dogma of molecular biology?

Possible Answers:

Correct answer:

Explanation:

The central dogma of molecular biology states that DNA is transcribed into RNA, which is then translated into protein.

Example Question #1 : The Central Dogma

Which one of the following lists the steps of the central dogma in the correct order?

Possible Answers:

DNA  RNA  Proteins

DNA  Enzymes  RNA  protein

DNA  Proteins  RNA

Proteins  RNA  DNA

DNA RNA Enzymes  Protein

Correct answer:

DNA  RNA  Proteins

Explanation:

The central dogma describes the flow of information from genes to a final protein. Initially, information is coded within DNA. During transcription, this information is transferred to RNA molecules. The RNA molecules are then transcribed to create functional proteins.

The correct sequence is: DNA  RNA  Proteins

Note that enzymes are a particular type of protein. Though enzymes can help with transcription and translation, they are not considered an independent step in the central dogma and fall under the more general category of "proteins."

Example Question #1 : Dna, Rna, And Proteins

Which of the following statements is false?

Possible Answers:

RNA is usually single-stranded, while DNA is usually double-stranded

RNA is more stable than DNA

RNA contains the nitrogenous base uracil

The RNA backbone contains the carbohydrate ribose

Correct answer:

RNA is more stable than DNA

Explanation:

Because RNA is usually single-stranded (vs. double-stranded DNA), it is more susceptible to degradation by nucleases; therefore, RNA is NOT more stable than DNA.

RNA does contain the carbohydrate sugar ribose in its backbone, while DNA contains the sugar deoxyribose. RNA contains the nitrogenous base uracil; in contrast, DNA contains thymine.

Example Question #1 : Dna, Rna, And Proteins

What is the name of the segment of DNA that RNA polymerase attaches to in order to initiate transcription?

Possible Answers:

Origin of replication

Terminator

Promoter

Operator

Correct answer:

Promoter

Explanation:

Transcription is initiated when RNA polymerase attaches to DNA at the promoter site. This allows the RNA polymerase to be appropriately positioned so that the whole gene is transcribed.

The origin of replication is the site that allows the initiation of DNA replication. Operators are segments of DNA that can bind transcription factors and regulate certain genes.

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