Topic 8- Exchange And Transport In Animals Flashcards
What waste products do your body produce and why must they be excreted?
All chemical reactions in your body produce wastes. They must be excreted so they don’t cause problems.
- Your kidneys produce urea, which is a poison produced by breaking down amino acids.
- your lungs get rid of carbon dioxide produced in aerobic respiration.
What kind of substances does your body intake?
- oxygen and glucose needed for aerobic respiration.
- dissolved food molecules (e.g glucose and amino acids) and mineral ions are needed to produce new substances for your body.
How did substances move in and out of our body and what adaptations allow this?
Substances move in and out of our body by diffusion. To make sure a lot of substances move quickly the substances need to be:
- thin (so particles don’t need to diffuse very far)
- have a large surface area (so there is more room for particles to diffuse)
Why do multicellular organisms need/have transport systems in their body? Give an example:
Because otherwise it would take too long for materials to diffuse through cells on the outside of a tissue to reach cells on the inside.
Ex: humans have a fine network of capillaries in the circulatory system to transport blood to and from cells.
How does surface area affect the diffusion rate?
The larger a cells surface the more substances that can diffuse into and out of it in a certain time. However, if a cells volume is too big then the cell cannot fill up with all the materials it needs fast enough.
How do you work out the surface area to volume ratio?
Surface area/ volume
THERE ARE NO UNITS
When the surface area to volume ratio increases how does this affect the surface area and volume?
The bigger the ratio, the more surface area something has per unit volume. As cells get bigger the SA:V ratio gets smaller. If the ratio is too small a cell cannot get enough raw materials on fats enough. So there is a limit to the cells size.
Describe the kind of SA:V ratio an organ in the human body that moves substances in to and about of body would have:
They would have SA:V ratios.
Ex: the human lung has a huge ratio because the lungs are packets worth millions of alveoli, which increase surface area and therefore increase amount of gas exchange.
What are alveoli?
They are…
How are alveoli adapted?
- one cell thick wall of alveolus.
- one cell thick wall of capillary means faster diffusion
- large surface area
- Blood enters from the body with a higher concentration of carbon dioxide and a lower concentration of oxygen.
- Blood goes to the rest of the body with a lower concentration of carbon dioxide and a higher concentration of oxygen.
Define concentration:
The amount of substance in a certain volume. Often measure in gcm 3 or gdm3.
What is 1dm equal to?
1dm =1 litre= 1000cm 3
What equation do you use to calculate the concentration of a solution in gdm3?
Concentration= mass of solute (g)/ volume of solution (dm3)
What happens during a net movement and what causes a net movement of particles?
The particles in a solution move randomly in all directions. This causes an over all ‘net’ movement of the solute particles from a high concentration to a low concentration. Not net movement occurs when concentrations are equal although the particles still move.
What does the difference between 2 concentrations form?
A concentration gradient. This bigger the difference, the steeper the concentration gradient and the faster the rate of diffusion.
What is meant by a directly proportional relationship?
As one variable increases by a certain amount/percentage, the other increase but the same amount/percent.
E.g
Rate of diffusion is proportional to the rate of concentration gradient.
What kind of concentration gradient in maintained in the lungs ?
To keep the rate of diffusion a high a steep concentration gradient must be maintained. In the lungs a good blood supply moves oxygen quickly out of the lungs and this maintains the concentration gradient.
When surface area increases what happens to rate of diffusion and why?
When SA (of a membrane) increases it means it means there is more space through which particles can pass. So more particles cross from one place to another in a certain time and so the overall rate of diffusion increases but. BUT... The rate at which particles pass through each unit area of the surface membrane in unchanged)
Rate if diffusion is proportional to the SA.
How does distance affect the rate if diffusion?
The further particles have to diffuse, the slower the rate of diffusion. So increasing the thickness of a membrane decreases the rate of diffusion. This means the relationship is inversely proportional. As one variable doubles the other halves.
What is Frick’s law?
It is…
How does Frick’s law link the variable to the rate of diffusion?
Rate if diffusion (proportional to) surface area x concentration difference/ thickness of membrane
Briefly how does the circulatory system work (using veins capillaries and arteries)?
Blood flows away from the heart into arteries. These divide into narrow capillaries, which form fine networks running through tissues. Blood returns to the heart in veins.
How do we feel a pulse?
With each beat our heart squirts blood into arteries under high pressure. This makes artery walls stretch and a wave of stretching then passes along the artery walls. You fell this as a pulse and not your blood moving.
