Biology DNA MCAS questions

#1 Which of the following statements describes a DNA molecule? A. It contains the base uracil. B. It has a double helix shape. C. It contains five phosphate groups per nucleotide. D. It has a backbone of twenty different nucleotides.

#2 The diagram below shows a pair of DNA nucleotides. The nitrogenous base guanine (G) is labeled. Which nitrogenous base pairs with guanine? A. adenine (A) B. cytosine (C) C. thymine (T) D. uracil (U)

#3 Radon is a radioactive gas that is sometimes present in homes. If radon is inhaled, its decay products are deposited in the lungs. Radioactive particles can penetrate cells and cause changes to the cells’ DNA. These changes in DNA are an example of which of the following? A. homeostasis B. mitosis C. mutation D. transcription

#4 In a molecule of double-stranded DNA, the amount of adenine present is always equal to the amount of A. cytosine. B. guanine. C. thymine. D. uracil.

#5 Which of the following describes the function of DNA? A. encoding genetic information B. storing energy in chemical bonds C. speeding up biochemical reactions D. destroying substances that enter the cell

#6 The diagram represents a process that occurs in the nucleus of a eukaryotic cell. Which of the following statements describes what is happening in this process? A. Molecules of RNA are forming chromosomes. B. A molecule of mRNA is directing the production of tRNA. C. Molecules of DNA are being packaged for export to the ribosomes. D. A molecule of DNA is being replicated to make two identical copies.

#7 In phenylketonuria (PKU), an enzyme that converts one amino acid into another does not work properly. Which of the following is the most likely cause of this genetic condition? A. an error in the transcription of the gene for the enzyme B. a mutation in the DNA sequence that codes for the enzyme C. an excess of the amino acids necessary to produce the enzyme D. a structural variation in the amino acid modified by the enzyme

The table below presents a variety of mRNA three-base sequences (codons) and the amino acids for which these sequences code. Based on the information in the table, which of the following changes is least likely to produce a phenotypic change in an organism? A. GAU to GGU B. GAU to GUU C. GAU to GAA D. GAU to GAC 1st Base of mRNA 2nd base of mRNA 3rd base of mRNA Amino Acid G A Glutamic acid C Aspartic acid U Glycine Valine #8

#9 Which of the following units are repeatedly joined together to form a strand of DNA? A. amino acids B. fatty acids C. nucleotides D. polysaccharides

The diagram below represents the beginning and end products of a process that occurs in the nucleus of a cell. Which process does the diagram represent? A. recombination B. replication C. transcription D. translation #10

#11 A laboratory technique called polymerase chain reaction (PCR) produces millions of copies of a DNA molecule in only a few hours. PCR is most similar to which of the following cellular processes? A. mitosis B. replication C. transcription D. translocation

#12 During DNA replication, the wrong nucleotide was inserted in the DNA sequence. Which of the following terms describes this situation? A. mutation B. regeneration C. transcription D. translation

#13 Huntington’s disease (HD) is a hereditary disease that destroys brain cells. In individuals with HD, the functioning of a specific protein is altered, and this leads to the disease’s effects. Which of the following is the most likely cause of the altered protein function in individuals with HD? A. a mutation in the DNA sequence that codes for the protein B. an increase in the amount of fat rather than protein in the diet C. a decrease in the amount of glucose and amino acids in the blood D. a structural abnormality in the endoplasmic reticulum of brain cells

#14 Which of the following features of DNA is most important in determining the traits of an organism? A. the direction of the helical twist B. the number of deoxyribose sugars C. the sequence of nitrogenous bases D. the strength of the hydrogen bonds

#15 Which of the following models most accurately represents the structure of DNA? A C B D

#16 In a eukaryotic cell, which of the following processes directly involves DNA? A. translation B. cellular respiration C. active transport of ions D. replication of chromosomes

#17 A portion of one strand of a DNA molecule has the sequence shown below. ACCTGAAGG Assuming there are no mutations in this portion of the DNA, what is the corresponding sequence on the complementary DNA strand? A. ACCTGAAGG B. GTTCAGGAA C. TGGACTTCC D. TGGACUUCC