Which of the following is true of purines?
A) Cytosine is a purine.
B) Adenine's bonding to thymine is stronger than is guanine's to cytosine.
C) Purines have a double-ringed structure.
D) Both adenine and thymine are purines.
E) Purines bind readily to deoxyribose but not to ribose.
C) Purines have a double-ringed structure.
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Suppose you are studying the nitrogen cycling in a pond ecosystem over the course of a month. While you are collecting data, a flock of one hundred Canada geese lands and spends the night during a fall migration
What could you do to eliminate error in your study as a result of this event? A) Find out how much nitrogen is consumed in plant material by a Canada goose over about a twelve-hour period, multiply this number by 100, and add that amount to the total nitrogen in the ecosystem. B) Find out how much nitrogen is eliminated by a Canada goose over about a twelve-hour period, multiply this number by 100, and subtract that amount from the total nitrogen in the ecosystem. C) Find out how much nitrogen is consumed and eliminated by a Canada goose over about a twelve-hour period and multiply this number by 100; enter this +/- value into the nitrogen budget of the ecosystem. D) Do nothing. The Canada geese visitation to the lake would have negligible impact on the nitrogen budget of the pond. E) Put a net over the pond so that no more migrating flocks can land on the pond and alter the nitrogen balance of the pond.
Tissues functioning together make up _____
A) organs B) membranes C) organ systems D) organelles E) organisms
The membrane protein that is bound by a chemical signal is called the ____
Fill in the blank with the appropriate word.
Which of the following is TRUE regarding plasmids?
A. Plasmids are small, usually a few thousand to ten thousand base pairs. B. Plasmids are linear. C. Plasmids are contained within the bacterial chromosome. D. Plasmids are rarely found in prokaryotes. E. Plasmids dominate in eukaryotes.