1. The cell membrane (also known as the plasma membrane) surrounding every cell is composed primarily of ______. DNA Protein Carbohydrates Phospholipids. A phospholipid molecule: composed of a phosphate group and two fatty acid tails.
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2. The phospholipids in the cell membrane are arranged in a bilayer (double layer). How are the phospholipid molecules arranged in this bilayer?
The hydrophilic phosphate groups facing outwards helps the cell interact with the watery environment on both sides of the membrane.
Additional energy is not required, because diffusion occurs due to the random motion of the molecules.
Hypo = below
Hypothermia is to have a body temperature below normal.
Hyperactive is to have high energy.
An isoceles triangle has two equal sides.
7. If a cell with a 0.7 %sucrose concentration inside is placed in a solution that has a 0.5% sucrose concentration, the process of osmosis will occur. In this case,
0.7 % sucrose
(Osmosis is occurring is a hint to this since it means the movement of water.)
Remember that while the solutions are described in terms of the solute concentration it is the water that moves.
The solution that has a lower solute concentration, has a higher water concentration.
Water will move from the hypotonic (low solute / higher water) towards the hypertonic (higher solute /lower water)
0.5% sucrose(99.5% water)
Paramecium living in fresh water ponds has to constantly pump out the water that flows into the cell.
8. If a cell with a 0.9% salt concentration inside is placed in a 1% salt solution, osmosis occurs. Which of the following will happen
Salt is an ionic compound that can not move through the nonpolar barrier of the phospholipid membrane (without specialized channels).
Net change = Inputs- Outputs. No net change when inputs and outs are balanced.
Dynamic equilibrium= an equilibrium (balance) is when there is motion but the inputs equal the outputs.
13. When a substance is secreted from a cell in a process in which a vesicle fuses with the plasma membrane to release the substance to the outside, it is called
In facilitated diffusion, a channel allows the substance to move through the membrane. But no energy is provided, so it is a type of passive transport and it can only move the substance from high concentration to low concentration.
Active transport is required to move from low to high concentration.
18. What will happen for the following set-up in which two different liquids are separated by a selectively-permeable membrane. The dots represent solute particles that can not move through the membrane.