Which one of the following statements is TRUE regarding the structure of the atom?
A) The nucleus is composed of equal numbers of positively charged particles and negatively charged particles.
B) All electrons are located at the same distance from the nucleus.
C) In small elements, such as carbon, electrons have a positive charge; in larger elements, such as barium, electrons have a negative charge.
D) Most of the mass of an atom is due to its protons and neutrons.
E) Neutrons carry a negative charge.
D
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One of the most important uses of the Gram stain of expectorated sputum received for routine bacteriologic culture is to:
a. give the physician a quick analysis of the type of organism causing the infection. b. evaluate the quality of the specimen. c. distinguish between the possibilities of bacterial and viral sources of infection. d. begin appropriate antimicrobial therapy as soon as possible.
You are working in a cancer lab and are interested in identifying some genes that are important in the onset of lung cancer. You have several genes you think may be involved, so you "print" spots of the DNA sequences of interest on a microarray slide. After doing this, you isolate mRNA from both normal lung cells and cancerous lung cells. Before you use these mRNAs to probe the microarray slide, you need to
A. make cDNA and amplify the cDNA using PCR. B. amplify the mRNA using PCR. C. clone each mRNA into a BAC vector. D. add reverse transcriptase and fluorescent nucleotides to the mRNA to make cDNA. E. sequence the mRNA.
The heart begins to beat.
Choose the letter of the best match: A. third trimester of pregnancy B. second month of pregnancy C. first month of pregnancy D. second trimester of pregnancy E. third month of pregnancy
Hamilton's Rule is a simple expression that specifies the conditions under which altruism will increase in frequency. What is this expression?
What will be an ideal response?