An atom has 20 electrons and 20 neutrons. What is the mass of this atom?
A. 10
B. 20
C. 40
D. 80
C. 40
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Consider the Calvin-Benson cycle and the noncyclic photosynthetic pathway. Why is the cyclic
pathway so important? What will be an ideal response?
Which type of cellular transport uses transport proteins and moves substances from an area of high concentration to an area of low concentration?
A) secondary active transport B) primary active transport C) facilitated diffusion D) simple diffusion E) phosphotransferase system
What evidence suggests when oxygen gas first
became a significant part of Earth’s atmosphere?
a. multi-celled microorganisms that breathed oxygen b. fossils of dinosaurs c. molten rock from volcanoes that were rich in oxygen d. rusty rocks indicating oxidized iron e. the presence of water vapor in the atmosphere
__________ counters the effects of mutation, natural selection, and genetic drift. Fill in the blank(s) with the appropriate word(s)