3.1 Surface area to volume & 3.2 Gas Exchange Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

How does an organism’s size relate to their surface area to volume ratio?

A

The larger the organism, the lower the surface area to volume ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does an organism surface area to volume ratio relate to their metabolic rate?

A

The smaller the surface area to volume ratio, the higher the metabolic rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How might a large organism adapt to compensate for its small surface area to volume ratio?

A

Changes that increase surface area e.g. folding; body parts becoming larger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why do multicellular organisms require specialised gas exchange surfaces?

A

Their small surface area to volume ratio means the distance that needs to be crossed is larger and substances cannot easily enter the cells as in a single-celled organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Name three features of an efficient gas exchange surface.

A

. Large surface area e.g. folded membranes in mitochondria
. Thin/short distance e.g. wall of capillaries
. Steep concentration gradient, maintained by blood supply or ventilation e.g alveoli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why can’t insects use their bodies as an exchange surface?

A

They have a waterproof chitin exoskeleton and a small surface area to volume ratio in order to conserve water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name and describe the three main features of an insects gas transport system

A

Spiracles= Holes of the body’s surface which may be opened or closed by a valve for gas or water exchange.
Tracheae = Large groups extending through all body tissue, supported by rings to prevent collapse.
Tracheoles = smaller branches dividing off the trachea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain the process of gas exchange in insects

A

. Gases move in and out of the tracheae through the spiracles
. A diffusion gradient allows oxygen to diffuse into the body tissue whilst waste CO2 diffuses out.
. Contraction of muscles in the trachae allows mass movement of air in and out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why can’t fish use their bodies as an exchange surface?

A

They have a waterproof, impermeable outer membrane and a small surface area to volume ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name and describe the two main features of a fish’s gas transport system

A

Gills = located within the body, supported by arches, along which are multiple projections of gill filaments, which are stacked up in piles.
Lamellae = at right angles to the gill filaments, give an increased surface area. Blood and water flow across them in opposite directions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain the process of gas exchange in fish

A

. The fish opens its mouth to enable water to flow in, then closes its mouth to increase. pressure
. The water passes over the lamellae, and the oxygen diffuses into the bloodstream
. Waste carbon dioxide diffuses into the water and flows back out of the gills

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the counter current exchange system maximise oxygen absorbed by the fish?

A

Maintains a steep concentration gradient, as water is always next to the blood of the lower oxygen concentration. Keeps rate of diffusion constant and enables 80% of available oxygen to be absorbed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Name and describe three adaptations of a leaf that allows efficient gas exchange.

A
  1. Thin and flat to provide short diffusion pathway and large surface area to volume ratio.
  2. Many minute pores in the underside of the lead (stomata) allows gases to easily enter.
  3. Air spaces in the mesophyll allow gases to move around the leaf, facilitating photosynthesis.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do plant limits their water loss while still allowing gases to be changed?

A

Stomata regulated by guard cells which allows them to open and close as needed. Most stay closed to prevent water loss while some open to let oxygen in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the pathway given by air as it enters the mammalian gaseous exchange system

A

Nasal Cavity –> trachea –> bronchi –> bronchioles –> alveoli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the function of the nasal cavity in the mammalian gaseous exchange system

A

A good blood supply warms and moistens the air entering the lungs. Goblet cells in the membrane secrete mucus which traps dusts and bacteria.

17
Q

Describe the trachea and its function in the mammalian gaseous exchange system.

A
  1. Wide tube supported by C-shaped cartilage to keep the air passage open during pressure changes.
  2. Lined by ciliated epithelium cells which move mucus towards the throat to be swallowed, preventing lung infections.
  3. Carries air to the bronchi
18
Q

Describe the bronchi and their function in the mammalian gaseous exchange system.

A

. Like the trachea they are supported by rings of cartilage and are lined by ciliated epithelium cells.
. However they are narrower and there are two of them, one for each lung.
. Allow passage of air into the bronchioles.

19
Q

Describe the bronchioles and their function in the mammalian gaseous exchange system

A

. Narrower than the bronchi.
. Do not need to be kept open by cartilage, therefore mostly have only muscle and elastic fibres so that they can contract and relax easily during ventilation.
. Allow passage of air into the alveoli.

20
Q

Describe the alveoli and their function in the mammalian gaseous exchange system

A

. Mini air sacs, lined with epithelium cells, site of gas exchange.
. Walls only one cell thick, covered with a network of capillaries, 300 million in each lung, all of which facilitates gas diffusion.

21
Q

Explain the process of inspiration and the changes that occurs throughout the thorax

A
  1. External intercostal muscles contract (while internal relax), pulling the ribs up and out.
  2. Diaphragm contracts and flattens.
  3. Volume of the thorax increases.
  4. Air pressure outside the lungs is therefore higher than the air pressure inside, so the air moves in to rebalance.
22
Q

Explain the process of expiration and the changes that occur throughout the thorax

A
  1. External intercostal muscles relax (while internal contract), bringing the ribs down and in.
  2. Diaphragm relaxes and comes upwards.
  3. Volume of the thorax decreases.
  4. Air pressure inside the lungs is therefore higher than the air pressure outside, so air moves out to rebalance.
23
Q

What is tidal volume?

A

The volume of air we breathe in and out during each breath at rest.

24
Q

What is breathing rate?

A

The number of breaths we take per minute

25
Q

How do you calculate pulmonary ventilation rate?

A

Tidal volume x breathing rate.
These can be measured using a spirometer, a device which records volume changes onto a graph as a person breathes.