biology chapter 3

How do facilitated diffusion and active transport differ?

Active transport uses energy and goes against the concentration gradient Facilitated diffusion doesn't require energy and uses ion channels or carrier proteins to move things down the concentration gradient.

What would happen to an animal cell with an internal salt concentration of 0.8% if it were placed in a salt solution with a concentration of 20% Why?

An animal cell that has an internal salt concentration of 0.8% would have dehydration synthesis occur when placed in a hypotonic solution of 20% salt solution. This is because the excess amount of salt will absorb the water from the cell and basically drain the cell of the water inside of it.

A hypertonic salt solution has a higher concentration of solutes than a blood cell. Explain what happens when a blood cell is placed in a hypertonic salt solution.

Because the blood is less hypertonic, water would rush out of blood cells into the solution shrinking the blood cells or shirviling it. This would happen until the outside environment and the blood have reached equilibrium.

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.

describe endo- and exocytosis

Endocytosis is a useful way for unicellular organisms or very simple multicellular organisms to get food into their internal environment. Exocytosis helps cells remove waste materials and specific molecules into the external environment.

comparing an contasting look at the graph in figure 7-6. Compare the lab results of the singe lab group with those collected by the rest of the class.

Line A shows that 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 25 mm, whereas the rest of the class found a distance of only 12 mm over the same period of time.

Predicting-DEscribe the movement of the c molecules on side of A of the apparatus shown in figure 7-4. What will happen to these molecules over time?

On side A the solution has a higher concentration of water because there is less solute. Some will move to side B and some will them move back to side A. Eventually, there will be equal amounts on both sides, and equilibrium will have been reached.

Predicting Look at Figure 7-4. Describe the movement of the D molecules on side A. What will happen to these molecules over time?

Some of the D molecules on side B will move to side A until there are equal amounts on both, and equilibrium has been reached.

What would happen if a cell's membrane became impermeable?

Substances wouldn't be able to go inside or outside the cell and they would be constant. They might be isotonic because the molecules would be moving equally in both directions.

Why is the cell membrane called "the fluid mosaic model"? Include the components of a cell membrane and their functions.

The cell membrane is like a fluid because it is flexible, able to repair itself when disturbed (polarity of phospholipids re-orient), and parts that make up the cell membrane like phospholipids and proteins can move laterally with the membrane itself. The membrane is like a mosaic because it is made individual phospholipids, proteins, carbohydrates, and cholesterol. The assembly of all these parts forms the overall structure of the membrane similar to how individual tiles in a mosaic form a pattern or picture.

Interpreting Graphics-Describe the experimental setup shown in figure 7-4. Do you expect the distribution of the solutes on each side of the membrane to change over time?

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. Yes, because the membrane is permeable to both kinds of molecules

Rattlesnake venom breaks down the walls of the glomerulus. Why does a rattlesnake bite cause blood to appear in the urine.

The glomerulus is a dense network of capillaries found in the nephrons of kidneys. If their walls were damaged blood would enter glomeruli and it would appear in the waste products. This would cause blood to appear in the urine.

Discuss the functions of the following structures of the urinary system: kidneys, ureter, urinary bladder, and urethra.

The kidneys filter metabolic wastes, excess ions, and chemicals from the blood to form urine. Gravity and peristalsis of smooth muscle tissue in the walls of the ureters move urine toward the urinary bladder. They prevent urine from flowing back towards the kidneys. Urine entering the urinary bladder from the ureters slowly fills the hollow space of the bladder and stretches its elastic walls. The walls of the bladder allow it to stretch to hold anywhere from 600 to 800 milliliters of urine. The urethra is the tube through which urine passes from the bladder to the exterior of the body.

Once equilibrium is reached in the apparatus shown in Figure 7-4, will the water molecules continue to move? Explain your answer.

The water molecules will continue to move back and forth across the membrane at equal rates. After equilibrium is reached the water is not trapped on either side but continues to be exchanged equally from side to side.

Drawing Conclusions In Figure 38-4, what is the name and function of structure G?

This structure, a collecting duct, collects impurities filtered from the blood and transports them to the ureter.

describe what happens when sugar solutions with two different concentrations are placed on opposite sides of a semipermeable membrane in a container

When sugar solutions of different concentrations are on opposite sides of a semipermeable membrane, the molecules on both sides of the membrane flow across the membrane. However, there is a net flow of molecules from the more concentrated solution into the less concentrated solution, until the concentrations are equal. Once equilibrium is reached, roughly equal numbers of molecules move in each direction across the membrane.

Comparing and Contrasting What two processes take place in the structures illustrated in Figure 38-4

filtration and reabsorption

infererring in what organ are the structures illustrated in figure 38-4 located

kidney

Interpreting Graphics In Figure 38-4, in which structure are useful substances reabsorbed into the blood?

the capillaries

diffusion

the movement of molecules from an area of higher concentration to an area of lower concentration.