B6A

A model of a DNA molecule is shown below. The arrow indicates -

• the bond between adjacent phosphate and deoxyribose molecules

• the junction of introns and exons in the sense strand of DNA

• the hydrogen bond between complementary nucleotides

• the junction of a codon and a DNA triplet

Characteristics such as a widow's peak or attached earlobes are determined by the genetic code. Which components of DNA are referred to as the genetic code?

• phosphate groups

• nitrogenous bases

• deoxyribose sugars

• hydrogen bonds

How does DNA in cells determine an organism's complex traits?

• DNA contains codes for proteins, which are necessary for the growth and functioning of an organism

• DNA separates into long single strands that make up each part of an organism

• DNA produces the energy an organism needs in order to grow

• DNA folds into the nucleus of each of the cells of an organism

The sequence of nitrogenous bases in DNA varies widely. The sequence of the bases in DNA is most important for which of the following?

• providing the instructions for the traits of an organsim

• preventing mutations from occuring during DNA replication

• allowing the DNA to have the shape necessary for replication

• helping form the sugar-phosphate backbone of DNA molecule

In 1952 Rosalind Franklin took the x-ray photograph shown below, which gave the world its first look at DNA. By studying this photograph, scientists gained knowledge about the -

• role of DNA in protein synthesis

• mutation of nucleotide sequences in DNA

• sequence of DNA that makes up the human genome

• double-helix structure of DNA

A segment of DNA is represented in the illustration. How is information for a specific protein carried on the DNA molecule?

• as a sequence of nucleotides

• in the double-helix shape of the condensed chromosome

• in the ratio of adenines to thymines

• as a pattern of phosphates and sugars

A student builds a model of a DNA strand. Which of these models of a DNA strand shows bases that are complementary to the ones on the students DNA molecule?

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Nitrogenous bases are located on both strands of the DNA double helix. What is the significance of the nitrogenous bases?

• the number of adenines and cytosines determines the type of RNA that will be produced

• the order of nitrogenous bases determines the order of amino acids in the proteins synthesized

• the amount of thymine and guanine in the DNA molecules determines the length of the genes

• the type of hydrogen bonding between the nitrogenous bases determines which amino acid will be added to the peptide chain

Each strand of a DNA molecule contains nitrogenous bases that pair with other nitrogenous bases in very specific ways. A diagram of a section of DNA is shown. Which DNA strand is complementary to the one shown above?

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Differences in traits such as hair texture are determined by differences in -

• the location of sugar groups in DNA

• the sequence of nucleotides in DNA

• the number of nitrogenous bases in DNA

• the molecules attached to the phosphate in DNA