Bio U1 - 1.4

Question 1

Describe simple diffusion.

Answer 1

The moving of particles from an area of high concentration to one of lower concentration without the use of energy.

Question 2

Explain two examples of simple diffusion of molecules into and out of cells. (can be different for everyone)

Answer 2

Gas exchange in the lungs through the alveoli cell and gas exchange by diffusion through the eye cornea cells

Question 3

Outline factors that regulate the rate of diffusion.

Answer 3

Temperature: increase temperature, increase diffusion rate
Pressure: increase pressure, increase diffusion rate
Concentration of the diffusing molecule: increase concentration, increase diffusing rate

Question 4

Describe facilitated diffusion.

Answer 4

Movement of molecules from a location of high concentration to one of low concentration using a channel protein but with no energy cost

Question 5

Describe one example of facilitated diffusion through a protein channel. . (can be different for everyone)

Answer 5

CFTR moves chloride from areas of high concentration to those of low concentration outside the cell

Question 6

Define osmosis.

Answer 6

The passive movement, diffusion, of water to areas of high concentration of solute and low concentration of water.

Question 7

Predict the direction of water movement based upon differences in solute concentration.

Answer 7

Low solute concentration to high solute concentration

Question 8

Compare active transport and passive transport.

Answer 8

Active: Requires the expenditure of ATP, against the gradient of concentration
Passive: Does not require ATP, in favor of the concentration gradient (high to low)

Question 9

Explain what happens to cells when placed in solutions of the same osmolarity, higher osmolarity and lower osmolarity.

Answer 9

Animal Cells:
Isotonic Solution - Same size
Hypotonic Solution - The cell will fill up and rupture
Hypertonic Solution - The cell will dehydrate
Plant Cells:
Isotonic Solution: Flaccid cells
Hypotonic Solution: Turgid cells
Hypertonic Solution: Plasmolysed cells

Question 10

Outline the use of normal saline in medical procedures.

Answer 10

Normal saline is the mixture of water and salt ions to the same concentration as the human cytoplasm, thus they are both isotonic. This is then used in medical procedures to ensure that the cells of an organ, when outside of the body, do not dehydrate or lyse (burst). Flushing wounds, eye washes, and IVs all use normal saline.

Question 11

Describe the fluid properties of the cell membrane and vesicles.

Answer 11

It refers to the viscous flow of phospholipids in the cell membrane and organelles of the endomembrane system.
Temperature
Fatty Acid Length
Fatty Acid Saturation
and Presence of Cholesterol all impact fluidity.

Question 12

Explain vesicle formation via endocytosis.

Answer 12

The cell actively transports the molecules in vesicles by engulfing them with the cell membrane.

Question 13

Outline two examples of materials brought into the cell via endocytosis.

Answer 13

White blood cells engulf bacteria when fighting infection
Amoeba engulf bacteria as food sources

Question 14

Explain release of materials from cells via exocytosis.

Answer 14

A secretory vesicle moves towards the cell membrane, fuses with it, then releases it into the extracellular space.

Question 15

​Outline two examples of materials released from a cell via exocytosis.

Answer 15

Secretion of neurotransmitters in neurons
Secretion of digestive juices from exocrine glands

Question 16

Describe the structure of the sodium-potassium pump.

Answer 16

It is opened to the K ions on the outside and has a spot for the ATP to use its energy to change the structure of the protein

Question 17

Describe the role of the sodium-potassium pump in maintaining neuronal resting potential.

Answer 17

Inside the neuron it is important to have more K ions than Na ions, but on the outside the opposite is true. With this, an electrical current can be formed and thus nervous impulses can be transmitted as well.

Question 18

Outline the six steps of sodium-potassium pump action.

Answer 18

1. When the pump is open to the inside of the axon, three sodium ions (Na+) enter the pump and attach to their binding sites.
2. ATP donates a phosphate group to the pump.
3. The previous stage causes the protein to change shape expelling Na+ to the outside.
4. Two potassium ions (K+) from outside then enter and attach to their binding sites.
5. The binding of the K+ leads to the release of the phosphate which causes the pump to change shape again so that it is only open to the inside of the axon.
6. K+ is released inside. Na+ can now enter and bind to the pump again.

Question 19

Describe the action of the “voltage gate” of the potassium channel.

Question 20

State two examples of active transport

Answer 20

Plant cells in the root of plants using ATP to diffuse minerals into them
Epithelial cells of the small intestine using ATP to move glucose into themselves