Thymine dimers are caused by
A) X-rays.
B) active oxygen species.
C) a mutagen such as ethylmethane sulfonate (EMS).
D) depurination.
E) UV light.
E) UV light.
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In the hydrologic cycle, water moves from the land to the air by ____ and returns to the land via ____
a. precipitation; evaporation and transpiration b. precipitation and evaporation; transpiration c. precipitation and transpiration; evaporation d. transpiration; precipitation and evaporation e. transpiration and evaporation; precipitation
Protective layers outside the bacterial cell membrane include:
a. cell walls only b. capsules only c. envelopes only d. cell walls and plasmids e. cell walls and capsules
Which latitude will have the most hours of daylight on the summer solstice?
a. 0º (the equator) b. 30º north c. 45º north d. 60º north
Which of the following is not true of the Chloroplastida (green algae)?
A. They have chlorophylls a and b. B. They store carbohydrates as starch. C. They are found in fresh and salt water. D. Their cell walls contain chitin.