3.3.1 Surface Area to Volume Ratio Flashcards
(SA:VOL Ratio) What does an organisms SA:VOL ratio affect?
How quickly substances are exchanged.
(SA:VOL Ratio) Describe the relationship between the size of an organism, its SA:VOL ratio and gas exchange?
The larger an organism becomes, the smaller its surface area to volume (SA:VOL) ratio.
(SA:VOL Ratio) Describe how single-celled organisms supply its cells with oxygen and glucose, and remove waste products.
The substances can diffuse directly into (or out of) the cell across the cell-surface membrane.
(SA:VOL Ratio) Describe the diffusion rate in single-celled organisms.
Quick because of the small distances that the substances have to travel.
(SA:VOL Ratio) Describe the diffusion rate in multicellular organisms.
Slow because:
1) Some cells are deep within the body (big distance between them and the outside environment).
2) Larger animals have a low SA:VOL ratio (difficult to exchange enough substances to supply a large volume of animal through a relatively small outer surface).
(SA:VOL Ratio) What do multicellular organism need to absorb and excrete substances?
- Specialised exchange organs (e.g. the lungs)
- An efficient system to carry substances to and from their individual cells (mass transport)
(SA:VOL Ratio) What does the rate of heat loss from an organism depend on?
The organism’s surface area.
(SA:VOL Ratio) What do smaller organisms need to generate enough heat to stay warm?
A relatively high metabolic rate.
(SA:VOL Ratio) What do animals with a compact shape have, and what does this minimise?
They have a small surface are relative to their volume, which minimises heat loss from their surface.
(SA:VOL Ratio) What do animals with a less compact shape have, and what does this increase?
They have a larger surface area relative to their volume, which increases heat loss from their surface.
(SA:VOL Ratio) State 3 examples of animals that have adapted body shapes to suit their environment.
Arctic fox, African bat-eared fox and European fox.
(SA:VOL Ratio) What do animals with a high SA:VOL ratio tend to lose more of and why is this a problem?
They tend to lose more water as it evaporates from their surface.
Problem for: animals living in hot regions where water evaporate quickly. Some small desert mammals have kidney structure adaptations so that they produce less urine to compensate.
(SA:VOL Ratio) What do small animals living in cold regions with high metabolic rates need to do?
Eat large amounts of high energy foods, such as seeds and nuts.
(SA:VOL Ratio) What adaptations might small mammals have/do for cold weather?
- Thick layers of fur
- Hibernate
(SA:VOL Ratio) How are elephants adapted, as a large organism living in hot regions?
Large flat ears which increase SA, allowing them to loose more heat.
