bio chapter 5 questions

Cells are rarely large enough to be visible due to restrictions of area/volume. How then can neuron cells reach lengths of up to several feet?

?

A(n) ______ solution has a higher concentration of dissolved particles than an adjacent solution.

hypertonic

Which method of transport can a cell use to bring in molecules without allowing them to pass through the plasma membrane?

receptor-mediated endocytosis

Why can't cells get as large as golf balls?

A cell that large would not have enough surface area to use in exchanging materials. (The larger the cell, the more nutrients it needs to pull in and the more waste in needs to expel. The volume outgrows the available surface area quickly.)

_____ aid in the coordination of the activities of adjacent animal cells.

Gap (communicating) junctions. (Gap junctions allow for the passage of material between cells, thus facilitating communication between these cells.)

Vibrio cholerae causes severe diarrhea in its victims. How might it cause this to occur?

It tricks the cells of the intestines into secreting ions.

What causes a plant to wilt?

The cells lose turgor pressure. (Plant cells with too little water in them shrink away from the cell wall due to loss of turgor pressure.)

How does the plasma membrane stop most substances from crossing it?

The non-polar fatty acid tails form a barrier to polar substances. (ons and polar molecules cannot cross the nonpolar interior of the membrane.)

What do channel proteins, aquaporins, and carrier proteins have in common?

They all perform facilitated diffusion. (No energy is expended when these membrane proteins allow their target molecules through.)

Which direction is water most likely to move if there is a membrane or concentration difference between two regions?

Water will move out of a hypotonic solution into a hypertonic solution. (Water is more likely to move from low solute concentration to high solute concentration.)

Which of the following scenarios is most similar to desmosomes?

cement between bricks in a wall

The primary role of _____ is to bind animal cells together.

desmosomes. (The primary role of desmosomes (anchoring junctions) is to bind cells together.)

Pinocytosis is one form of ______, the movement of large materials into a cell by an infolding of the plasma membrane.

endocytosis

Which membrane proteins increase the rate of chemical reactions?

enzymatic proteins. (These are enzymes attached to the inner face of the plasma membrane.)

______ is the movement of materials out of a cell through the fusion of a transport vesicle with the plasma membrane.

exocytosis

Which type of transport requires assistance from membrane proteins, but no energy?

facilitated diffusion. (This form of passive transport requires a transport protein, but since it only works if you can move the substance down a concentration gradient, it does not require energy (such as ATP).)

Identify Structure A.

glycoprotein.

What is the word for membrane proteins that have carbohydrates attached to them?

glycoprotein.

A(n) ______ solution has the same concentration of dissolved particles as an adjacent solution.

isotonic

When molecules move down their concentration gradient, they move from where they are ______ to where they are ______.

more concentrated, less concentrated.

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

Diffusion across a biological membrane is called ______.

passive transport.

Facilitated diffusion is a type of _____.

passive transport. (During facilitated diffusion, the cell is not expending energy to move the particles across the membrane; therefore, facilitated diffusion is a form of passive transport.)

______ is the movement of large materials into a cell by wrapping extensions of the plasma membrane around the material and engulfing it by fusing the extensions together.

phagocytosis

Some white blood cells in the human body are able to engulf bacteria and destroy them. What should this engulfing process be called?

phagocytosis.

Identify Structure D.

phospholipid bilayer of membrane. (Phospholipids can be recognized by the presence of a head and two tails.)

You can recognize the process of pinocytosis when _____.

the cell is engulfing extracellular fluid

Embedded within the phospholipid bilayer surrounding a cell are ______, which regulate the movement of hydrophilic molecules from one side of the plasma membrane to the other.

transport proteins

Which of the following is most like a gap junction?

a nuclear pore. (Gap junctions and nuclear pores are both channel proteins that cross between membranes.)

You know that this cell is in a(n) _____ solution because it _____.

hypertonic solution ... lost water. (A cell will lose water when placed in a hypertonic solution.)

This cell is in a(n) _____ solution.

hypertonic. (There is a greater concentration of solute outside the cell.)

A(n) ______ solution has a lower concentration of dissolved particles than an adjacent solution.

hypotonic

You know that this cell is in a(n) _____ solution because the cell _____.

hypotonic ... swelled. (A cell will gain water when placed in a hypotonic solution.)

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

How does a freshwater Paramecium counteract osmosis (and avoid becoming too swollen with water)?

it pumps salt into a contractile vacuole, drawing excess water in to be squeezed out of the cell. (Pumping salt into the contractile vacuole causes water to flow into it and be pumped out of the cell when the vacuole squeezes.)

Where can the phosphate portion of the phospholipids in a membrane be found?

on the surfaces of the bilayer, facing the outside liquid or the cytoplasm inside. (The phosphate head is hydrophilic; therefore, it will either face the water outside the cell or the water inside the cell.)

What is the function of Structure E?

stabilization of the phospholipids. (Cholesterol helps to stabilize the structure of the plasma membrane.)

Which of these cell junctions form a barrier to the passage of materials?

tight junctions. (Tight junctions form a barrier that prevents fluids from moving between cells.)