SB8 Exchange and Transport in Animals Flashcards
Why do we transport substances in the body?
- to remove waste substances
- to gain energy
How do many substances move into and out of the body?
Diffusion
Volume and surface area aren’t proportional. What problems does this cause in multicellular organisms?
- insufficient area to meet their needs
- volume increases which slows diffusion
What are specialised exchange surfaces?
Surfaces that allow for efficient transport of substances from one area to another
What are some adaptations of specialised exchange surfaces?
- short diffusion distance: thin membrane
- large surface area
- having an efficient blood supply
What is a SA:V ratio?
The ratio of surface area to volume of an object/organism. It impacts the function of exchange surfaces by determining the efficiency of the exchange
What is concentration?
The amount of substance in a certain volume
How is concentration calculated?
mass of solute (g) / volume of solution (dm^3)
What is a concentration gradient?
The difference in concentrations. It is the overall net movement of particles from a high concentration to a low concentration
Why does distance affect the rate of diffusion?
If the distance is small, diffusion occurs faster because particles don’t have to travel as far
Why does surface area affect the rate of diffusion?
The larger the surface area, the higher the number of particles that will be able to move in a given time, so the faster the rate
Why does concentration affect the rate of diffusion?
The bigger the difference in the concentration gradient, the faster the rate of diffusion
What is Fick’s Law?
A law that describes the relationship between the rate of diffusion and the three factors that affect it
rate of diffusion is directly proportional to (surface area x concentration difference)/ thickness of membrane
When will the rate of diffusion double?
- surface area or concentration difference is doubled
- thickness of membrane is halved
What is the role of the blood?
- transports materials
- distributes heat around the body
- protects against disease
What are the components of blood?
- plasma
- red blood cells
- white blood cells
- platelets
What is the role of plasma?
The liquid that carries the components in the blood
What is the role of red blood cells?
Transporting oxygen. They must be able to absorb oxygen in the lungs, pass through narrow capillaries, and release this oxygen to respiring cells
What is the role of white blood cells?
Ingesting pathogens and producing antibodies
What is the role of platelets?
Involved in blood clotting
What are the adaptations of a red blood cell?
- contain the protein haemoglobin giving them their red colour
- no nucleus
- small and flexible so they can fit through narrow capillaries
- biconcave shape to maximise their surface area
- thin, reducing diffusion distance
What are the adaptations of a white blood cell?
- 70% are phagocytes, which surround foreign cells and digest them
- 30% are lymphocytes, which produce antibodies during an infection to destroy foreign cells
- their quantity increases during an infection
- have a nucleus
What are the adaptations of an alveoli?
- one cell thick, providing a short diffusion pathway
- capillaries provide a good blood supply, maintaining a concentration gradient for diffusion of substances
- small and arranged in clusters, which increases the SA:V ratio