EXCHANGE SUBSTANCES WITH ENV. Flashcards
(17 cards)
What does a high SA:V ratio mean?
- Short distance from the edge to the middle
- Things can get in and out quickly
What does a low SA:V ratio mean?
- Long distance from the edge to the middle
- Things take a long time to get in and out
What is metabolic rate?
- The amount of energy expended by that organism in a time period
What is metabolic demand?
- How much oxygen and nutrients an organism needs to take in daily to respire enough to maintain the metabolic rate
Why the greater the mass of an organism, the higher the metabolic rate?
- Require more efficient delivery of oxygen to cells as more respiration is needed
What are 2 things about a unicellular organism?
- Have large SA:V
- Diffusion distance is short
What is an advantage and disadvantage of an unicellular organism?
- ADV: Can exchange materials directly with their environment as all of cell has surface exposed to the outside
- DISADV: Lose heat, energy and water quickly, can’t survive extreme heat or cold
What are 2 things about multicellular organisms?
- Have small SA:V
- Diffusion distance is long
What is an advantage and disadvantage of a multicellular organism?
-ADV: Lose less energy as heat, so can survuve more easily in cold environments
- DISADV: Some cells will have no surface exposed to the outside, therefore needs an internal mass transport system
What is the behavioural adaptation?
Env: Cold Challenge: Heat loss
- Small mammals with large SA:V will lose heat easily so they need to eat large amounts of high energy foods such as nuts and seeds to maintain body temperature
- May hibernate during the coldest months
What is the physical adaptation and an example?
Env: Cold Challenge: Heat loss
- Have a streamlined compact body shape giving a smaller SA:V
- Thick layers of fur around the body to insulate and reduce heat loss
- Arctic Fox has small ears and a round fsce to reduce SA:V and heat loss
What is the behavioural adaptation?
Env: Hot desert Challenge: Overheating
- Large organisms such as hippos spend most of the day in the water to lose heat
- Organisms may be nocturnal so they’re more active in cooler temperatures
What is the physical adaptation and an example?
Env: Hot desert Challenge: Overheating
- Large organisms with a low SA:V have large ears which increase SA allowing them to lose more heat
- Elephants
- African bat-eared fox has large ears and a pointed nose to increase SA:V and heat loss
What is the behavioural adaptation?
Env: Hot/dry desert Challenge: Water loss
- Organisms may be nocturnal so that they are more active during cooler temperatures
What is the physical adaptation?
Env: Hot/dry desert Challenge: Water loss
- Small mammals with a high SA:V have kidney structure adaptations so that they produce less urine to compensate for water lost through evapouration
What is a carbohydrase?
Type of digestive enzyme which hydrolyses carbohydrates to monosaccharides
What is an illeum?
- Long muscular tube where food is further digested
- Enzymes are produced by its walls and by glands that pour their secretions into it
- Inner walls are folded into villi which give large SA
- Where products of digestion are absorbed into bloodstream
