Exam pack 6 Topic 1,2,3 - Mistake

Question 1

Describe how oxygen in air in the alveoli enters the blood in capillaries

Answer 1

1. O2 diffuses into capillaries
2. Across the alveolar epithelium

Question 1

Air moves into lungs between times p and q. Explain how the diaphragm causes this?

Answer 1

MP1 - The diaphragm contracts
MP2 - This increases the volume in the thoracic cavity
MP3 - Air moves down pressure gradient into lungs

Question 2

Explain 2 ways in which the structure of the fish gills is adapted for efficient gas exchange

Answer 2

1. Lots of laemallae and filament - increase surface area
2. Thine surface - short diffusion pathway

Question 3

6 marker - some substances pass through the plasma membrane of a milk producing cell by diffusion.
Describe the structure of the plasma membrane and explain how different substances are able to pass through the membrane by diffusion

Answer 3

1. The plasma membranes is formed by phospholipids arranging themselves into a phospholipid bilayer
2. The phospholipid bilayer consists of hydrophilic phosphate heads, that face towards the aqueous conditions, while the hydrophobic fatty acid tails face away from the aqueous conditions.
3. The plasma membrane also consists of channel and carrier proteins, through which facilitated active transport can happen
4. The plasma membrane also consists of glycoprotein
5. Substances that can pass through the plasma membrane by diffusion are small, lipid soluble, non- charged and non-polar substances

Question 4

Explain how counter current mechanism in fish gills ensure the maximum amount of the O2 passes into blood flowing through gills.

Answer 4

1. Blood in fish flows in the opposite direction to water flow
2. This ensures that the blood directly next to the water will always have a lower concentration of oxygen than the water it is next to
3. This maintains a high concentration gradient of O2 throughout the whole length of the gill, and ensures equilibrium is not reached.

Question 5

When investigating the affect of 2 injectstilns on the conc of antibodies in the blood, why would we in general give 2 injections?

Answer 5

One dose probably will not result in high enough levels of antibodies for them to be effective

Question 6

Although the vaccine is made of antigens from malarial parasites, it does not cause malaria. Why?

Answer 6

The antigen will require the parasite to cause malaria
They themselves do not cause the disease.

Question 7

The blood from those taking part in the trail was also examined under the microscope at the beginning of the trail. Explain how this would enable those who had malaria to be identified

Answer 7

malaria sufferers will have parasites in red blood cells.