The World RNA Hypothesis

What does DNA stand for?

• Deoxyribonucleic Acid

• Deoxyribose Nucleic Acid

• Deoxyribonitrogen Acid

• Deoxyribophosphate Acid

Answer explanation

DNA stands for Deoxyribonucleic Acid, which is the correct term for the molecule that carries genetic information. The other options are incorrect variations that do not accurately describe DNA.

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DOK Level 1: Recall

Which of the following is NOT a part of a nucleotide in DNA?

• Deoxyribose

• Phosphate group

• Ribose

• Nitrogen-containing base

Answer explanation

Ribose is not part of a DNA nucleotide; instead, DNA contains deoxyribose. The other components of a DNA nucleotide are a phosphate group and a nitrogen-containing base.

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DOK Level 1: Recall

Identify the nitrogen-containing base that is NOT found in DNA.

• Adenine

• Guanine

• Cytosine

• Uracil

Answer explanation

Uracil is a nitrogen-containing base found in RNA, not DNA. DNA contains adenine, guanine, and cytosine, but uracil is replaced by thymine in DNA.

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DOK Level 1: Recall

What is the primary function of DNA in living organisms?

• To store energy

• To provide structural support

• To hold instructions for growth and function

• To transport oxygen

Answer explanation

The primary function of DNA is to hold instructions for growth and function. It contains the genetic blueprint that guides the development and functioning of all living organisms, making it essential for life.

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DOK Level 1: Recall

Which sugar is found in the structure of DNA?

• Ribose

• Glucose

• Deoxyribose

• Fructose

Answer explanation

The sugar found in the structure of DNA is deoxyribose. Unlike ribose, which is found in RNA, deoxyribose lacks one oxygen atom, making it essential for the stability and structure of DNA.

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DOK Level 1: Recall

Explain how the sequence of bases in DNA determines the sequence of amino acids in a protein.

• The sequence of bases in DNA is transcribed into mRNA, which is then translated into a sequence of amino acids.

• The sequence of bases in DNA directly forms amino acids.

• The sequence of bases in DNA is converted into lipids, which then form amino acids.

• The sequence of bases in DNA is used to create carbohydrates, which then form amino acids.

Answer explanation

The correct choice explains that the DNA sequence is first transcribed into mRNA. This mRNA is then translated into a sequence of amino acids, which form proteins, highlighting the central dogma of molecular biology.

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DOK Level 2: Skill/Concept

Compare DNA and RNA in terms of their sugar components.

• Both DNA and RNA contain deoxyribose.

• DNA contains deoxyribose, while RNA contains ribose.

• Both DNA and RNA contain ribose.

• DNA contains ribose, while RNA contains deoxyribose.

Answer explanation

DNA contains deoxyribose, which lacks one oxygen atom compared to ribose found in RNA. This key difference in sugar components is crucial for the structural and functional roles of these nucleic acids.

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DOK Level 2: Skill/Concept

Describe the role of proteins in the human body.

• Proteins store genetic information.

• Proteins carry oxygen in the blood and fight off infections.

• Proteins provide energy for cellular processes.

• Proteins act as a primary source of genetic mutations.

Answer explanation

Proteins play crucial roles in the body, including transporting oxygen via hemoglobin and defending against pathogens through antibodies, making the correct choice about their function in immunity and oxygen transport.

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DOK Level 2: Skill/Concept

What is the significance of the order of nitrogen-containing bases in DNA?

• It determines the type of sugar in the DNA molecule.

• It determines the sequence of amino acids in a protein.

• It determines the number of nucleotides in the DNA strand.

• It determines the length of the DNA molecule.

Answer explanation

The order of nitrogen-containing bases in DNA is crucial because it encodes the genetic information that determines the sequence of amino acids in proteins, ultimately influencing their structure and function.

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DOK Level 2: Skill/Concept

Why do scientists believe that early life on Earth was based on RNA rather than DNA?

• RNA is more stable than DNA.

• RNA can store genetic information and catalyze chemical reactions.

• RNA is less complex than DNA.

• RNA is found in all living organisms.

Answer explanation

Scientists believe early life was based on RNA because it can both store genetic information and catalyze chemical reactions, making it versatile for early biological processes, unlike DNA which is primarily a storage molecule.

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DOK Level 2: Skill/Concept