BIO 121 EXAM 3 STUDY QUESTIONS AND CORRECT ANSWERS
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Course
BIO 121
Institution
BIO 121
The early earth's atmosphere had almost no free oxygen (O2). Now it is almost 20% O2. Where did all this O2 come from? Photosynthesis
Endocytosis and exocytosis are important for what? Endocytosis- vesicle pinches inward and moves a bubble of solutes into cells, membrane dissolves in cell and free...
BIO 121 EXAM 3 STUDY QUESTIONS
AND CORRECT ANSWERS
The early earth's atmosphere had almost no free oxygen (O2). Now it is almost 20%
O2. Where did all this O2 come from? ✅Photosynthesis
Endocytosis and exocytosis are important for what? ✅Endocytosis- vesicle pinches
inward and moves a bubble of solutes into cells, membrane dissolves in cell and frees
them (NO atp) signals on the outside membrane attract what we need and enfold when
they come near
exocytosis - send them out (No atp)
They regulate what is in the cell, cell homeostasis
Glucose, fatty acids, and proteins can all be used to make the principal energy carrying
molecule in cells. What is this molecule? ✅ATP (Adenosine Tri-Phosphate)
Describe photosynthesis in general terms. ✅Converts solar energy into the chemical
energy of carbohydrates which not only sustains the plant but all other life on Earth.
What happens to cells in hypertonic versus isotonic solutions? ✅Isotonic: equal
balance of solute in the cell and outside it
Hypertonic: More solute outside than inside
Osmosis involves water diffusing through a membrane. What controls this movement?
Can you describe osmosis in general terms? ✅net flow of water through membranes,
Water will diffuse through a membrane from an area with more water to an area with
less water.
Osmotic pressure: Tendency for water to move into any cell
In class we learned that Dr. Peter Agre won the Nobel Prize in 2003 for his discovery of
aquaporins. What are this molecules and why are they important? ✅Aquaporins:
Specialized water channels (in vs out)
What is passive transport and active transport (and their steps) and what role does ATP
play? ✅Passive transport-No energy needed, shape allows to go through
Active transport
Primary transport: H+ pumps out
Secondary transport: H+ in along with another molecule
Moves molecules against concentration gradient
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