Science 8B Lesson 7: DNA & Genes

Which best describes a gene?

• a type of pants

• a molecule within DNA

• a set of chromosomes

• a segment of DNA that codes for a protein

Answer explanation

A gene is a segment of DNA that codes for a protein.

In a DNA molecule, what nitrogen base does adenine (A) pair with?

• Adenine (A)

• Cytosine (C)

• Thymine (T)

• Guanine (G)

Answer explanation

In a DNA molecule, adenine (A) pairs with thymine (T). 

What is the shape of a DNA molecule?

• strands of RNA

• circular

• double helix

• one straight strand of nucleotides

Answer explanation

A DNA molecule has the shape of a double helix.

What are the subunits of a nucleotide in DNA?

• a sugar, a phosphate group, and a nitrogen-containing base

• a sugar, a phosphate group, and an oxygen-containing base

• a lipid, a phosphate group, and a nitrogen-containing base

• a sugar, a carbon group, and a nitrogen-containing base

Answer explanation

A nucleotide includes a sugar (deoxyribose), phosphate group, and nitrogen-containing bases).

What determines the code, or information, of a DNA molecule?

• the order (sequence) of the nitrogen bases

• the shape (structure) of the nitrogen bases

•  

  the length of the strand of DNA

• the number of sugar and phosphate groups

What carries the code for making proteins to the ribosomes?

• thymine

• DNA

• RNA

• Cytosine

Answer explanation

RNA carries the code for naming proteins to the ribosome.

Which best summarizes the central dogma of biology?

• DNA - RNA - Protein

• DNA + RNA = Protein

• RNA → DNA → Protein

• DNA → RNA → Protein

Answer explanation

The flow of directions from DNA to RNA to proteins according to the central dogma.

Which process makes a copy of a DNA molecule?

• transcription

• mutation

• translation

• replication

Answer explanation

Replication is the process of making a copy of a DNA molecule.

Which is an example of a harmful mutation?

• A woman has a gene that makes it harder for her to get a specific disease.

• A hummingbird with a longer beak that is able to gather more nectar.

• A dog with one blue eye and one brown eye.

• An alligator with an albinism gene that makes it white instead of greenish-brown.

Answer explanation

A mutation like albinism is harmful.

Examine the following mutation: ACGG → ACGTWhat type of mutation occurred?

• a substitution

• a deletion

• an inversion

• an insertion

Answer explanation

A substitution occurred because the last G was replaced with a T.