Science 7.3 7.4
What will the apparatus shown in Figure 7-10 look like when equilibrium is reached?
At equilibrium, Side A will have less water than Side B and the concentration of solute molecules will be equal on either side of the selectively permeable membrane.
An iodine solution (IKI or Lugol's solution) turns from yellow-brown to blue when it reacts with starch, but not when it reacts with glucose. A bag made from a selectively permeable material and containing iodine solution is placed into a beaker containing a solution of glucose and starch. Using only this information, which of the following can be correctly concluded if the solution in the beaker turns blue but the contents of the bag remain unchanged in color? A. Glucose moved from the beaker into the bag. B. The bag is permeable to IKI, but not to starch. C. The bag is permeable to IKI and glucose, but not to starch. D. The bag is permeable to IKI, but not to starch and glucose.
B. The bag is permeable to IKI, but not to starch
Explain, in terms of osmosis, why a raisin placed in a cup of pure water overnight will puff up with water.
Because the concentration of water in the cup is greater than the concentration of water in the raisin, water will flow from the cup into the raisin.
Which statement best describes how channel and carrier proteins in the plasma membrane are similar
Both allow for the flow of molecules into and out of a cell
A cell in a multicellular organism must be able to carry out all of the functions necessary for life in order for the organism to survive.
False, unicellular
Look at the graph in Figure 7-12. Compare the lab results of the single lab group with those collected by the rest of the class
Line A shows the single group's results are quite different from the results of the rest of the class. Over a half-hour period, the lab group found that the solution traveled 25mm, whereas the rest of the class found a distance of only 12 mm over the same period of time. The distance traveled in the lab group's data also kept increasing, whereas the class' data leveled out at about 10 minutes
Exocytosis
Process by which a cell releases large amounts of material
Which of the following activities are a way that unicellular organisms maintain homeostasis
Reproduction, growth, response to the environment
Which of the following is most involved in providing structure for a plasma membrane
The arrangement of the hydrophobic and hydrophilic ends of the phospholipids
Describe the experimental setup shown in Figure 7-10
The experimental setup shows a solution with differing concentrations of solute separated by a selectively permeable membrane. The membrane is permeable to water but not the solute.
What could account for the difference in lines A and B in the graph in Figure 7-12
The lab group(line A) might have used a more concentrated solution of sucrose or a membrane with a different permeability
Look at Figure 7-10. Describe the movement of water in the experimental setup. What will happen to the concentration of water over time?
The membrane is permeable to water so water can cross the membrane in both directions. Over time, there will be a net movement of water toward Side B, which has a higher concentration of solute particles.
Look at the graph in Figure 7-12. How would the results differ if a sucrose solution with twice the concentration of the one used to collect the results represented by line A were used
The more concentrated the solution, the longer distance the solution will travel over the same period of time. Thus, a more concentrated solution would produce a longer distance
How might you use the graph in Figure 7-12 to calculate the rate of osmosis observed? What units would you use to report the rate
The rate of osmosis could be calculated by dividing the distance traveled by time l. The units would be mm/min
Which results in the graph in Figure 7-12 are more likely to be accurate, those represented by line A or by line B? Why?
The rest of the class's results(line B) are more likely to be accurate because they represent a larger sample size
How does the solution of Side A of the apparatus shown in Figure 7-10 differ from the solution on Side B
The solution on Side A has fewer solute particles than the solution on Side B. Both solutions have the same amount of water, so the solution on Side A is hypotonic compared to the solution on Side B
Which statement best describes a function of the proteins embedded in the plasma membrane of cells
They selectively allow certain particles into and out of the cell.
Once equilibrium is reached, roughly equal numbers of molecules move in either direction across a semipermeable membrane, and there is no further change in concentration on either side of the membrane.
True
There is a division of labor among the cells of multicellular organisms.
True
Once equilibrium is reached in the apparatus shown in Figure 7-10, will the water molecules continue to move? Explain your answer
Yes, the water molecules will continue to move across the membrane; however, there will not be a net movement from one side to the other.
The cells of unicellular organisms are
able to carry out all of the functions necessary for life
Which means of particle transport is shown in Figure 7-4 above?
active transport
Which means of particle transport requires input of energy from the cell?
active transport
What structure serves as the cell boundary from its environment
cell membrane
The cells in a multicellular organism have specific jobs. This is called cell
cell specialization
During diffusion, when the concentration of molecules on both sides of a membrane is the same, the molecules will
continue to move across the membrane in both directions
Which means of particle transport is shown in Figure 7-5 above?
endocytosis
Which transport mechanisms require the formation of a vesicle to transport material into or out of a cell
exocytosis and endocytosis
Example of an organ
heart
Which term describes the relatively constant internal physical conditions of an organism?
homeostasis
The diffusion of water across a selectively permeable membrane is called
osmosis
An animal cell that is surrounded by fresh water will burst because the osmotic pressure causes
water to move into the cell
