Transport Systems Flashcards
Why do all organisms need a transport system? 4
- All cells need energy
- Energy requires respiration
- Respiration requires raw materials e.g glucose/oxygen
- Must be delivered to all cells
What do unicellular organisms have meaning they can use diffusion as a transport system?
- A high surface area to volume ratio
- Short distance to needed cells, substances can diffuse directly across cell membrane
- It transports nutrients to it fast enough to meet its small energy requirements
What type of transport system do unicellular organisms use?
Diffusion
Define “unicellular”.
Single celled organism
Why can’t multicelluar organisms rely on diffusion?
- Low surface area to volume ratio
- Large distances need to be travelled to reach all cells
- Diffusion is too slow to meet
requirements of high metabolic rate and energy needs
What do multicellular organisms need for transport?
- A mass transport system that moves substances effectively over long distance by mass flow
- Specialised organs e.g lungs increase SA:Vol ratio for effective exchange
What is the main type of mass transport system?
The circulatory system
What is mass flow?
The circulation of blood maintaining a high concentration gradient
What does blood do in the circulatory system?
Carries raw materials from specialised organs to body cells and removes metabolic waste
What are the 4 types of circulatory system?
- Open
- Closed
- Single
- Double
What organisms use an open circulatory system?
- Small multicellular organisms
- E.g insects, earthworms
Describe an open circulatory system. 5
- Blood carrying vital substances circulates in open large spaces
- Heart pumps blood out into cavities surrounding animal’s organs
- Substances diffuse between blood and cells
- Heart muscle relaxes
- Blood is drawn from the cavity back into the heart through small valved openings along its length
What type of organisms use closed circulatory system?
Large multicellular
Why do large multicellular organisms need a closed circulatory system?
Larger and more active
Where is blood in a closed circulatory system?
Blood is enclosed within tubes - blood vessel
Describe a closed circulatory system. 4
- Blood vessels generate high pressures
- Blood is forced along narrow channels instead of flowing into large cavities
- Flows along arteries then arterioles then capillaries
- Blood returns to heart through venules then veins
Give an organisms that has a single circulatory system.
Fish
Describe a single circulatory system in fish.
- Heart pumps deoxygenated blood to gills
- Gaseous exchange takes place in the gills [Co2 from blood to water surrounding gills and vice versa with oxygen]
- Blood leaving gills flows around rest of body before returning to heart
Define “single circulatory system”
Blood flows through heart once for each complete circuit of the body
Define “double circulatory system”
Blood flows through heart twice for each complete circuit of the body
What organisms use a double circulatory system?
Birds and mammals with a high metabolic rate
Describe a double circulatory system. 2
- Right ventricle of the heart pumps deoxygenated blood to the lungs
- Oxygenated blood returns to the heart to be pumped a second time by left ventricle out to the rest of the body
