A double-stranded DNA molecule can be separated into single strands by heating it to 90°C because _______________________
(a) heat disrupts the hydrogen bonds holding the sugar–phosphate backbone together.
(b) DNA is negatively charged.
(c) heat disrupts hydrogen-bonding between complementary nucleotides.
(d) DNA is positively charged.
(c)
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Root nodules are
a. intertwined roots of different species of plants. b. connecting points between branching roots. c. symbiotic associations between a fungus and plant roots. d. specialized root hairs. e. localized swellings in plant roots filled with nitrogen-fixing bacteria.
Which of the following contribute to the successful application of Koch's postulates?
A) the development of the compound microscope B) the theory of abiogenesis C) the ability to record the appearance of bacteria photographically D) the development of simple bacterial staining techniques E) the development of techniques for sterile transfer of bacteria
The use of microorganisms to produce useful products is known as
A) biotechnology. B) gene modification. C) genomics. D) recombinant DNA technology. E) cloning.
During penetration of an Escherichia coli cell by the T4 bacteriophage,
a. the envelope fuses with the cell membrane, allowing the phage nucleocapsid to enter the cell. b. integrase makes a pore in the cell wall, the tail sheath contracts, and the phage DNA is injected into the cell. c. T4 lysozyme makes a pore in the cell wall, the tail sheath contracts, and the phage DNA is injected into the cell. d. T4 lysozyme facilitates membrane fusion, allowing the phage to enter the cell.