SB8 - Exchange and transport in animals Flashcards
Why do organisms need to transport substances out of the body?
To prevent waste products from accumulating
Where does the exchange of substances occur?
Across the cell membrane
What do specialised exchange surfaces allow?
Efficient transport of substances from one area to another
What are the transport processes that organisms use?
- Diffusion
- Osmosis
- Active transport
Why do unicellular organisms not need to have specialist exchange surfaces or transport systems?
As diffusion, osmosis and active transport through the cell membrane occur at a sufficient rate to meet the needs of the organism
Why do multicellular organisms need to have specialist exchange surfaces or transport systems?
As the distance between the surface of the organism to its centre is relatively long
—> As diffusion, osmosis and active transport cannot happen sufficiently to meet a larger organism’s needs otherwise
Why do large, multicellular organisms need exchange surfaces?
Large, multicellular organisms already have relatively small surface areas (SA) in comparison to their volumes
Give an example of transport systems in animals
Blood & circulatory system
Give an example of transport systems in plants
- Xylem
- Phloem
Give some examples of some exchange surfaces
- Root hair cells of plants
- Walls of nephrons in the kidneys
What are some common characteristics of exchange surfaces?
- Short distance for diffusion
- Large surface area
How does having a large surface area aid exchange surfaces?
Greater the surface area = the more particles can move through
—> Resulting in a faster rate of diffusion
How does having a thin membrane aid exchange surfaces?
Provides a short diffusion pathway, allowing the process to occur faster
How does having an efficient blood supply (in animals) aid exchange surfaces?
Creates a steep concentration gradient, so diffusion occurs faster
Why can single celled organisms use diffusion to transport molecules into their body?
They have a relatively large surface area to volume ratio
—> They have low metabolic demands, diffusion across the surface of the organism meets demands
What is the purpose of alveoli?
Allows gas exchange between the lungs and blood
How is alveoli adapted to diffusion?
- Walls of alveoli are thin
- Capillaries provide a large blood supply
- Very small & arranged in clusters
How does alveoli being small & arranged in clusters aid diffusion?
Creating a large surface area for diffusion to take place over
How does alveoli having a large blood supply aid diffusion?
Maintains the concentration gradient
How does alveoli having thin walls aid diffusion?
There is a short diffusion pathway
What are the factors which affect the rate of diffusion?
- Temperature
- Surface area of the membrane
- Concentration gradient
Describe the effect of concentration gradient on the rate of diffusion?
The greater the difference in concentration, the faster the rate of diffusion
—> Bc more particles are randomly moving down the gradient than are moving against it
Describe the effect of temperature on the rate of diffusion?
The greater the temperature, the greater the movement of particles
—> More collisions therefore faster rate of diffusion
Describe the effect of surface area of the membrane on the rate of diffusion?
The greater the surface area, the more space for particles to move through
—> Faster rate of diffusion
What is the equation used to calculate the rate of diffusion?
What is the blood made up of?
- Plasma
- Red blood cells
- White blood cells
- Platelets
What is the purpose of platelets?
Cell fragments that have no nuclei - important in the clotting mechanism of the blood
What is the purpose of the red blood cells?
They carry oxygen molecules from the lungs to all the cells in the body
List how red blood cells are adapted to its function?
- Biconcave disc shape
- No nucleus
- Contains haemoglobin
How does red blood cells having a biconcave disc shape help its function?
Provides a large surface area
How does red blood cells having no nucleus help its function?
Allows more room to carry oxygen
Describe why blood can be dark red
There is less oxygen attached to the haemoglobin molecules
Describe why blood can be bright red
There is a lot of oxygen attached to the haemoglobin molecules
What is the purpose of the plasma?
The liquid that carries the components in the blood
What is the purpose of the white blood cells?
They are a part of the immune system
What are the types of white blood cells?
- Phagocytes
- Lymphocytes
What are the types of blood vessels?
- Arteries
- Veins
- Capillaries
What is the purpose of arteries?
Carries blood AWAY from the heart
Describe how the arteries are adapted to its function
- Layers of muscle in the walls make them strong
- Elastic fibres allow them to stretch
This helps the vessel to withstand the high pressure created by pumping of the heart
What is the purpose of veins?
Carries blood TOWARDS the heart
Describe how the veins are adapted to its function
- The lumen is wide to allow the low pressure blood to flow through
- They have valves to ensure the blood flows in the right direction
What is the purpose of capillaries?
Allows the transfer of substances between the blood and tissues
Describe how the capillaries are adapted to its function
- One cell thick - short diffusion pathway
- Permeable walls - substances can move across them
What is the circulatory system?
The system that moves blood through the body and removes waste products
Describe the structure of the heart
- Muscular walls
- Muscular wall of the left ventricle is thicker
- 4 chambers that separate the oxygenated blood from the deoxygenated blood
- Valves
- Coronary arteries cover the heart to provide its own oxygenated blood supply
What is the purpose of muscular walls in the heart?
Provides a strong heartbeat
Why is the muscular wall of the left ventricle thicker in the heart?
Blood needs to be pumped all around the body rather than just to the lung like the right ventricle
What is the purpose of the valves in the heart?
To prevent the backflow of blood
Which side of the heart is oxygenated blood?
Left
Which side of the heart is deoxygenated blood?
Right
What is the average natural resting rate of the heart?
70bpm
What system does the heart use to pump blood around the body?
Double circulatory
Describe the pathway of blood
- Blood flows into the right atrium through the vena cava, and left atrium through the
pulmonary vein - Atria contracts forcing the blood into the ventricles
- The ventricles contract, pushing the blood in the right ventricle into the pulmonary artery to be taken to the lungs & blood in the left ventricle to the aorta to be taken around the body
When is an artificial pacemaker used?
When the individual has an irregular heartbeat
What is the equation for cardiac output?
What is stroke volume?
The volume of blood expelled from the heart in one contraction
What is heart rate?
The number of beats per minute
What is cellular respiration?
An exothermic reaction which is a series of chemical reactions that release energy from glucose
Why is respiration exothermic
Some energy is transferred out of the cells by heating - keeps animals warm
Compare aerobic respiration w/ anaerobic respiration?
Why do organisms need energy?
- Chemical reactions
- Muscle contraction
- Keeping warm
What is aerobic respiration?
The chemical reaction in cells that uses oxygen to break down nutrient molecules to release energy
What is anaerobic respiration?
The chemical reaction in cells that breaks down nutrient molecules to release energy without using oxygen
What is the formula for lactic acid?
What is oxygen debt?
The amount of oxygen required to break down the lactic acid that has built up
Why is lactic acid dangerous for our bodies?
Lactic acid builds up in muscle cells and lowers the pH of the muscle tissue (making the conditions more acidic)
—> Acidic conditions can denature the enzymes in cells
What is repaying the oxygen debt?
The process of breaking down the lactic acid
What other organisms apart from humans can anaerobically respire?
- Plants
- Yeast
What is fermentation important in?
- Brewing
- Manufacture of bread
Core practical: Rate of respiration in living orgaisms
Describe the method you will use to conduct this experiment
Pick a small organism that you would like to measure the rate of respiration of (e.g
maggots, or leaves)
- Place 5cm 3 of soda lime into a test tube
- Place gauze on top and a small amount of the organism being tested on top of this
- Attach a three-way tap, capillary tube and syringe to the test-tube. Plug the test-tube
with a stopper - Insert a small amount of coloured liquid into the capillary tube
- Turn the 3-way tap to allow air to enter the test tube for 5 minutes. After 5 minutes,
close the 3-way tap. - Record how far the coloured liquid has moved against a scale.
What is a respirometer?
A machine to measure the effect of temperature on the oxygen consumption of small organisms
Describe how a simple respirometer should look like
