Chapter 7 Homework
passive transport
Facilitated diffusion is a type of _______
Lipids are mostly non polar, whereas sugars are polar.
How can a lipid be distinguished from a sugar?
Proteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity.
How does the "fluid mosaic model" describe the structure of the plasma membrane?
Phospholipids
Which of the following molecules are most abundant in the plasma membrane?
Endocytosis
A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process?
Carbon Dioxide
Which of the following molecules is most likely to passively diffuse across the plasma membrane?
The cell will decrease in size as water flows out of it.
Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell?
transports sodium ions out of the cell and transports potassium ions into the cell
The sodium-potassium pump
True
True or false? Osmosis is a type of diffusion.
True
True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.
More, Less
When molecules move down their concentration gradient, they move from where they are ____concentrated to where they are ___ concentrated.
Plasma Membrane
Which of the following cell structures exhibits selective permeability between a cell and its external environment?
Active transport uses ATP, where facilitated diffusion does not.
Which of the following is a correct difference between active transport and facilitated diffusion?
These proteins exhibit both hydrophilic and hydrophobic properties.
Which of the following is correct regarding integral proteins?
These proteins are found only on the surface of the plasma membrane.
Which of the following is correct regarding peripheral proteins?
water, oxygen, carbon dioxide, lipids
Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.
Oxygen (O2)
Which of the following particles could diffuse easily through a cell membrane?
A cell placed in a hypotonic solution
Which of the following plant cells would exhibit the most turgor pressure?
Exocytosis and smooth and rough ER
Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane?
it is a passive process
Which of the following statements about diffusion is true?
Passive transport permits the solute to move in either direction, but the net movement of the population of solute molecules occurs down the concentration gradient of the molecule.
Which of the following statements about passive transport is correct?
Phospholipids form a selectively permeable structure.
Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?
Membrane carbohydrates function primarily in cell-cell recognition.
Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?
Proteins embedded in two layers of phospholipids
Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability?
A nonpolar molecule, such as a hydrocarbon
Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein?
The solution is hypertonic.
A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution?
to little sodium in the blood stream
A person suffering from hyponatremia has which of the following?
phagocytosis
A white blood cell engulfing a bacterium is an example of _____
membrane potential; electrogenic pumps
All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________.
B; the diffusion gradient in cell B is steeper
Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________ because __________.
into ... membranous vesicles
Endocytosis moves materials _____ a cell via _____
At body temperature, it makes the membrane less fluid.
How does cholesterol affect membrane fluidity?
osmosis
Hyponatremia is the result of what process?
Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.
If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?
Hypotonic (salt concentration in solution is lower than cell, so water enters cell, causing it to burst)
If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?
Channel, carrier
In facilitated diffusion, __________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and __________ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape.
that the salt in the food creates a hypertonic environment for the bacteria and fungi
Many bacteria and fungi have a difficult time surviving on our food if the food is very salty. The best explanation for this is
freshwater lakes and ponds.
Paramecium is a genus of protists that lives in water. It has organelles called contractile vacuoles that continually eliminate the excess water gained through osmosis. Knowing that Paramecia gain water through osmosis, we can deduce that they normally live in
1.0M
The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?
the plasma membrane allows some substances to flow through it more easily than others
The plasma membrane exhibits selective permeability. This means that
Cell-to-cell recognition
What function do carbohydrates fulfill in the plasma membrane?
Amphipathic nature
What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?
The polarity of membrane phospholipids
Which of the following factors does not affect membrane permeability?
A large polar molecule
Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein?
I AM SURE Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.
Which of these statements describes some aspect of facilitated diffusion?
Because it moves solutes against their concentration gradient
Why is energy required for active transport?
lose water by osmosis.
what happens if a HUMAN CELL is placed into a hypertonic solution?
