Radical Radishes

Two atoms are isotopes of the same element. Which of the following should be the same for these two atoms?

• The number of protons

• The number of electrons

• The number of neutrons

• The number of molecules

Which of the following correctly compares the phosphorus isotopes ³¹P and ³²P?

• ³¹P has 31 neutrons, whereas ³²P has 32 neutrons.

• ³¹P has 31 protons, whereas ³²P has 32 protons.

• ³¹P has 16 neutrons, whereas ³²P has 17 neutrons.

• ³¹P has 16 protons, whereas ³²P has 17 protons.

Which of the following molecules is used to make radioactively labeled DNA?

• Fatty acid

• Glucose monomer

• Radioactive nucleotide

• Amino acid

33P is a radioactive isotope of phosphorus. Can 33P be used to make a radioactive nucleotide?

• Yes, because it can replace the phosphorus atom in the phosphate group.

• Yes, because all isotopes of an element give off radiation.

• No, because an isotope is a different form of an element.D.

• No, because it is chemically different from other isotopes of phosphorus.

Which of the following can be used to determine the general location of radioactively labeled DNA?

• Sugar ring

• Geiger counter

• DNA polymeras

• pH meter

Which explains how a probe can find a single-stranded target DNA gene?

• The target gene matches two probes to form a three-stranded DNA.

• The probe makes all the DNA strands in an experiment radioactive.

• The probe is the second strand of DNA that forms double-stranded DNA with the target gene.

• The probe carries a signaling molecule that can detect the gene.

Which of the following determines the specificity of a DNA probe?

• Type of radiation

• Complementary base pairing

• Level of enzymatic activity

• Number of neutrons

In an experiment, a scientist makes a radioactively labeled probe using viral DNA. She then discovers that the probe hybridizes to a small segment of DNA isolated from human tissue. What can she conclude from her results?

• A plant cell has a cell wall, whereas a human cell does not.

• Plant DNA was accidentally used as a template to make the probe.

• The wrong method was used to detect radioactively labeled DNA.

• The plant might have a gene that is similar to a human gene.

Which of the following describes a DNA mutation?

• The packaging of DNA into a structure called a chromosome

• The linking of free nucleotides into a long chain

• A change in the nucleotide sequence of a gene

• The substitution of uracil for thymine in RNA

What could be a good effect of a mutation?

• Less variety in a population.

• DNA does not function properly

• DNA is destroyed.

• More variety in a population