Exchange and Transport Module 3:Section 1

Question 1

Why do organisms need to exchange substances with their environment?

Answer 1

1) cells need to take in o2 and glucose for aerobic respiration and metabolic processes
2) they also need to excrete waste products eg co2 and urea

Question 2

Do smaller animals have a higher or lower SA:V ratio?

Answer 2

Higher eg hippo has 2:1 but a mouse has 6:1

Question 3

Why do multicellular organisms need exchange surfaces ?

Answer 3

Due to diffusion across the outer membranes being too slow, due to:
1) some cells are deep within body so bigger distance between them and outside environment
2) low SA:V difficult to exchange substances through a small membrane to a large volume of animal.
3) higher metabolic rate therefore uses up more o2 and glucose

Question 4

Large SA example

Answer 4

Root hair cell
Has cells that grow into millions of hairs. This increases the rate of absorption of water by osmosis and mineral ions by active transport

Question 5

Thin examples

Answer 5

Alveoli: Have alveolar epthilium (thin and flat cells). These decrease the distance over which co2 and o2 diffusion takes place this increases the rate of diffusion.

Question 6

Good blood supply and ventilation examples

Answer 6

Eg alveoli - large capillary network gives each alveolus its own blood supply. Blood consistenantky takes o2 away and brings co2.
Lungs are also ventilated so air can be constantly replaced. Maintains condo gradient of o2 and co2.

Question 7

What does the trachea have?

Answer 7

C-shaped cartilage
Smooth muscle
Elastic fibres
Goblet cells
Ciliates epithelium

Question 8

What does the bronchi have?

Answer 8

Small pieces of cartilage
Smooth muscle
Elastic fibres
Goblet cells
Ciliated epithelium

Question 9

What does the different type of bronchioles have?

Answer 9

Large bronchioles - has no cartilage but has smooth muscle, elastic fibres and has goblet cells
Smaller bronchioles - no cartilage, smooth muscle and elastic fibres but no goblet cells
Smallest bronchioles- no cartilage, no smooth muscle has elastic fibres but no goblet cells and no cilia

Question 10

What does the alveoli have?

Answer 10

No cartilage, no smooth muscle has elastic fibres but no goblet cells and no cilia

Question 11

Inspiration

Answer 11

Inter coastal muscles relax
Outercoastal muscles contract
Diaphragm contracts
Rib cage moves up and out
Thorax volume increases
Lung pressure decreases
Active process so requires energy

Question 12

Expiration

Answer 12

Opposite

Question 13

What does tidal volume mean

Answer 13

Volume of air in each breath taken

Question 14

Vital capacity

Answer 14

Max vol of air taken in and out

Question 15

Breathing rate

Answer 15

How many breaths are taken - usually in a min

Question 16

O2 consumption

Answer 16

The rate at which an organism uses up o2

Question 19

Adaptations of fish

Answer 19

Gills - thin branches(called gill filaments ) and lamallae which are tiny structures. Gives it a big SA more exchange of gases

Gill arch - support each gill

Lamellae - has network of capillaries and has thin layers of cells which give it a shorter diffusion distance to speed up diffusion.

Question 20

Countercurrent systems

Answer 20

Blood and water flow through gills in opposite directions.
Blood enters gill plates with a low conc of o2 and leaves with high conc of o2
Whereas water enters with a high conc and leaves with a low conc.
This maintains a larger conc gradient between water and blood.