As you and a friend are entering a chemistry laboratory at your university, you see a sign that states: DANGER-RADIOACTIVE ISOTOPES IN USE. Your friend is an accounting major and has not had any science courses yet. She asks you what a radioactive isotope is and you respond correctly with
A. radioactive isotopes are atoms that are stable and as a result only emit energy if they are exposed to higher temperatures.
B. radioactive isotopes are atoms that are unstable and as a result emit energy in a process called radioactive decay.
C. radioactive isotopes are atoms that are stable and as a result emit energy in a process called radioactive decay.
D. radioactive isotopes are atoms that are unstable but unless actively disturbed by some chemical process will remain intact and pose no problems.
Answer: B
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Place the steps of biofilm formation in the correct order. _____ Surface (substratum) is preconditioned by environmental molecules. _____ Quorum sensing and the establishment of the extracellular matrix commences as microbes attach more stably. _____ Biofilm matures and some microorganisms escape to the planktonic state. _____ Microbes attach and detach from the preconditioned surface.
Fill in the blank(s) with the appropriate word(s).
Which represents the charged environment inside a resting neuron and the interstitial fluid that surrounds it?
a. negatively charged proteins inside; more sodium ions inside than outside; more potassium ions outside than inside b. positively charged proteins inside; more sodium ions inside than outside; more potassium ions outside than inside c. negatively charged proteins inside; more sodium ions outside than inside; more potassium ions inside than outside d. positively charged proteins inside; more sodium ions outside than inside; more potassium ions inside than outside e. negatively charged proteins inside; equal amounts of sodium and potassium ions inside and outside
Which of the following is true of both positive and negative gene regulation?
a. They directly reduce the rate of transcription of certain genes. b. They involve transcription factors (or RNA) binding to DNA. c. They involve transcription of all genes in the genome. d. They are not both active in the same organism or virus. e. They act away from the promoter.
DNA made from an RNA template will be incorporated into the virus capsid of
A) Retroviridae. B) Herpesviridae. C) Hepadnaviridae. D) bacteriophage families. E) influenzavirus.