C7

Question 1

What are 2 reasons why Diffusion alone is enough to supply the needs of a single celled organism

Answer 1

1. Metabolic activity of a small organism is usually low
2. The surface area : Volume ratio is large

Question 2

What 4 features to all effective exchange services have in common

Answer 2

Increase surface area, thin layers, good blood supply, ventilation to maintain diffusion gradient

Question 3

Why is it important for a specialized exchange surface to have a good blood supply

Answer 3

A good blood supply means a constant supply of gases meaning a steep concentration gradient is maintained

Question 4

What is the function of the nasal cavity

Answer 4

Large surface area, good blood supply, warm air to body temperature. Hairy Lining Secrete mucus to trap dust and bacteria. Moist surfaces

Question 5

What is the structure and function of the trachea 

Answer 5

Supported by strong, flexible cartilage, which stops the trachea from collapsing.

The trachea and it’s branches are lined with cilliated epithelium. With Goblet cells that produce mucus. The cilia beat and move the mucus away from the lungs.

Question 6

Why are the cartilage surrounding the trachea C shaped and not O shaped.

Answer 6

So that food can move down the esophagus

Question 7

What is the structure and function of the bronchioles

Answer 7

Bronchi divide into many small bronchioles, the walls contain smooth muscle.
When the smooth muscle contracts the bronchioles constrict and when the smooth muscle relaxers the bronchioles dilate
They are also lined with a thin layer of flattened epithelium, making some gaseous exchange possible.

Question 8

What is the structure and function of the alveoli

Answer 8

Tiny air sacs, Main site of gas exchange. Unique too Mammalian lungs. 
One layer of thin flattened epithelium cells, along with some collagen and elastic fibers. The elastic tissue Allows them to stretch when air enters and recoil to draw air out (elastic recoil of the lungs)