Exchange Systems

Question 1

What are the three methods of transport in the human body?

Answer 1

1. Diffusion - the passive movement of particles form a high concentration to a low concentration until equilibrium through a partially permeable membrane. Follows the concentration gradient. Liquids and gases.
2. Osmosis - the passive net movement of water particles from a dilute to a less dilution concentration through a partially permeable membrane until equilibrium. Follows conc. gradient. Water only.
3. Active transport - the active movement of particles from a region of low concentration to a region of higher concentration through a partially permeable membrane. Does not aim for equilibrium. Goes against conc gradient. Mineral ions and glucose.

Question 2

What are the five main organ systems of the body?

Answer 2

1. Circulatory
2. Nervous
3. Digestive
4. Excretory
5. Respiratory

Question 3

Explain the importance of a small surface area to volume ratio.

Answer 3

Large organisms have a small surface area to internal volume ratio b/c diffusion only through the external surface area would be too slow to deal with their requirements.

Question 4

How are alveoli adapted to ensure efficient gaseous exchange? (3)

Answer 4

1. Elastic recoil and expansion - after inhaling both the surface area and the volume increase, allowing more oxygen to be taken in.
2. Receive a very rich blood supply (fast blood flow) - allows oxygen to be released into the bloodstream and the absorption of carbon dioxide into the alveoli to be released as waste.
3. Thin cell membrane - ensures a short diffusion distance and therefore efficient gaseous exchange.

Question 5

How are villi adapted to their function?

Answer 5

Finger-like protrusions in small intestine - increases surface area to volume ratio for more efficient active transport

Question 6

Name and describe the function of the organelles of an animal cell.

Answer 6

1. Partially permeable cell membrane - allows particular sized substances in and out of the cell.
2. Nucleus - contains genetic material of the cell, which codes for its functions. Site of transcription.
3. Ribosome - location of protein synthesis.
4. Cytoplasm - Site of anaerobic respiration and key metabolic reactions.
5. Mitochondria - sight of aerobic respiration.

Question 7

Describe the process of hemolysis.

Answer 7

1. Once a red blood cell is placed in a hypotonic solution (solution with low solute concentration), water molecules diffuse into the cell.
2. This causes it to swell and burst (turgid), releasing substances like hemoglobin into the bloodstream.

Question 8

Describe the process of crenation.

Answer 8

1. When a red blood cell is placed in a hypertonic solution (solution with higher solute concentration), osmotic pressure causes the water molecules to diffuse out of the cell.
2. This causes the cell to shrink or become crenated.

Question 9

What happens when a red blood cell is placed in an isotonic solution?

Answer 9

1. Isotonic solution = when the outside and inside concentrations are equal.
2. There is no net movement of particles b/c equilibrium has already been achieved.

Question 10

How can hemolysis and crenation be prevented?

Answer 10

Active transport can be controlled by carrier proteins in the partially permeable membrane.