Which statement explains why greenhouse gases are needed for the survival of life on Earth?
A.
Greenhouse gases are clean sources of energy.
B.
Without greenhouse gases, Earth would be too cold for life to exist.
C.
Inhaling greenhouse gases is essential for proper lung function.
D.
Greenhouse gases prevent celestial objects from entering Earth’s atmosphere.

b

Explanation:

Greenhouse gases keep our planet livable by holding onto some of Earth's heat energy so that it doesn't all escape into space. This heat trapping is known as the greenhouse effect. Just as too little greenhouse gas makes Earth too cold, too much greenhouse gas makes Earth too warm.

g1

choices:

a. g2. b. g1. c. m

cell division has two checkpoints namely, g1

checkpoint and spindle assembly checkpoint. the checkpoint which determines if

division has properly occurred is the g1 checkpoint. at this point, is a damage

in the dna is detected or  the has not reach the optimum size, the cell is

stopped in g1 and is not allowed to proceed to further process.

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