3A - Exchange And Transpor Systems Flashcards
Name 5 things an organism needs to exchange with its environment.
- Oxygen
- Nutrients
- Carbon dioxide
- Urea
- Heat
How does the shape and size of an organism affect the rate of substance exchange?
The higher the surface area to volume ratio, the faster the rate of gas exchange.
Compare the surface area to volume ratio of a mouse and a hippo.
- Mouse -> Large SA:V ratio
* Hippo -> Small SA:V ratio
What are the 3 categories of exchange substances in an organism?
- Supply reactants (e.g. glucose)
- Waste products (e.g. urea)
- Heat
Compare and explain gas exchange systems in single-called and multicellular organisms.
- Single-celled -> Diffuse through the cell membrane -> Short distance for diffusion
- Multicellular -> Require exchange organs and mass transport systems -> Diffusion through surface is too slow
Why can’t multicellular animals exchange substances through their surface?
- Some cells are deep within the body -> Big distance between them and the surface
- Small SA:V ratio -> Diffusion is too slow
Instead of exchanging substances through their surface, what do multicellular animals do?
They have specialised exchange organs and mass transport systems.
What is a mass transport system?
A system that carries substances to and from individual cells.
Describe mass transport in mammals.
The circulatory system carries in blood: • Glucose • Oxygen • Hormones • Antibodies • Waste (e.g. CO2)
Describe mass transport in plants.
The xylem and phloem carry:
• Water
• Solutes
Describe the effect of being a large animal on heat loss and how large animals deal with this in a hot environment.
Large size -> Small SA:V ratio -> Difficult to lose heat -> Have a less compact shape (e.g. large ears) to lose heat + Low metabolic rate
Describe the effect of being a small animal on heat loss and how small animals deal with this in a cool environment.
Small size -> Large SA:V ratio -> Easily lose heat -> Have a more compact shape (e.g. small ears) to lose less heat + High metabolic rate
What two factors of an organism’s physique affect heat loss?
- Size
* Shape
Compare the metabolic rate of small and large animals in the same environment.
- Small -> High metabolic rate
* Large -> Low metabolic rate
Compare the shape of small and large animals in the same environment.
- Small -> Compact shape (e.g. small ears)
* Large -> Less compact shape (e.g. large ears)
Give some examples of adaptations of animals in hot regions.
- Small animals produce less urine -> Compensate for high levels of water loss through surface
- Large animals may have large ears (e.g. elephants)
- Large animals may spend time in water (e.g. hippos)
Give some examples of adaptations of animals in cold regions.
- Small mammals eats high energy foods, such as nuts and seeds -> Support the high metabolic rates
- Small mammals have thick fur
- Small mammals may hibernate
What are the three types of adaptation?
- Structural / Physical
- Behavioural
- Physiological
What is a structural/physical adaptation?
A feature of an organism’s body that helps it survive.
What is a behavioural adaptation?
A response or behaviour of an organism that helps it survive.
What is a physiological adaptation?
A body process that helps an organism survive.
What 3 features are common to all exchange surfaces?
1) Large surface area
2) Thin
3) Steep concentration gradient
How does the thickness of an exchange surface affect the rate of diffusion across it?
The thinner it is, the shorter the diffusion pathway, which increases the rate of gas exchange.
How thick are most gas exchange surfaces?
Often only 1 cell thick.