SB8 - Exchange and Transport In Animals Flashcards
SB8a
1) Recall the names of substances that need to be transported into and out of the body.
2) Describe the functions of the substances that are transported into the body.
3) Why do some organisms need both specialised exchange surfaces and a mass transport system in order to survive?
1) The substances that need to be transported into the body in order to survive include: oxygen, mineral ions, water, dissolved food.
2) Oxygen and glucose are needed for aerobic respiration. Dissolved food molecules (eg. glucose, amino acids) and mineral ions are needed to produce new substances for your body.
3) Many organisms are multicellular. Multicellular organisms cannot simply exchange all the substances that they need across the outer surface of their body. They need specialised exchange surfaces for efficient diffusion of substances into and out of their body, and a mass transport system to carry substances around their body.
SB8a
1) Describe the adaptations of the lungs for gas exchange.
2) Calculate surface area : volume ratios.
3) Explain the importance of surface area : volume ratios in transport systems.
1) The alveoli have a moist lining to allow gases to dissolve. The walls of the alveoli are one cell thick. This means that the substances have a shorted diffusion distance. There are many alveoli in the lungs, and the alveoli have air sacks, to maximise the total surface area over which gas exchange takes place. Therefore, lungs have a large surface area : volume ratio. These adaptations increase the speed and amount of gas exchange.
2) The surface area: volume ratio (SA:V) is calculating by dividing the surface area by the volume (surface area /volume).
3) Organisms that move substance in and out of the body have large SA:V ratios. This is to increase the speed and amount of gas exchange. Small SA:V ratios will mean that it will take longer for substances to diffuse.
SB8b
1) Describe what is meant by concentration and use appropriate units.
2) Describe how surface area affects the rate of diffusion.
3) Describe how concentration gradient affects the rate of diffusion.
1) A concentration is the amount of substance in a certain volume. A common unit is g/cm³ or g cm⁻³
2) If the surface area of a membrane is increased, there is more space through which particles can pass. This means that more particles cross from one place to another in a certain time, and so the overall rate of diffusion increases (but the rate at which particles pass through each unit area of the surface membrane is unchanged).
3) The difference between two concentrations forms a concentration gradient. The bigger the difference, the steeper the concentration gradient and the faster the rate of diffusion. Therefore, increasing the concentration increases the rate of diffusion.
SB8b
1) Describe how distance affects the rate of diffusion.
2) What is Fick’s Law?
3) Explain why there is a limit to how large a cell can be.
1) 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 is an inversely proportional relationship. As one variable doubles, the other halves.
2) Fick’s Law for the rate of diffusion across a membrane:
Rate of diffusion is proportional to (the surface area x concentration difference) / thickness of membrane
3) As cells get bigger, the surface area to volume ratio decreases. It then takes too long for materials to diffuse through the cell.
SB8d
1) Recall the parts of the heart (chambers, arteries, veins, valves)
2) Describe the flow of blood through the heart.
3) How are the left and right sides of the heart seen on diagrams?
1) The heart has four chambers - two atria (in the top half) and two ventricles (in the bottom half).
The vena cava is the vein that deoxygenated blood enters through, and goes to the right atrium.
The pulmonary vein is one of the veins that carries oxygenated blood to the heart from the lungs, and goes to the left atrium.
Blood leaves the heart in the body’s main artery - the aorta (Main artery which carries oxygenated blood from the heart) - from the left side, and the pulmonary artery (The artery which carries deoxygenated blood from the heart to the lungs) , from the right.
Valves are present to prevent blood flowing backwards.
Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body. Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs. Blood is pumped towards the heart in veins and away from the heart in arteries.
The coronary arteries supply the cardiac muscle tissue of the heart with oxygenated blood.
2) Deoxygenated blood coming from the body flows through the vena cava and into the right atrium. The atrium contracts and the blood is forced through the valve into the right ventricle. The ventricle contracts and the blood is pushed through the valve into the pulmonary artery. The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place.
Oxygenated blood returns via the pulmonary vein to the left atrium. The atrium contracts and forces the blood through the valve into the left ventricle. The ventricle contracts and the blood is forced through the semilunar valve and out through the aorta.
3) The heart is labelled as if it was in the chest so the left side of a diagram is actually the right hand side and vice versa.
SB8d
1) Explain how the heart is adapted for its function (valves, differing ventricle muscle thicknesses).
2) Recall and use the equation that relates cardiac output, stroke volume and heart rate.
1) Differing ventricle muscle thicknesses: the wall of the left ventricle is thicker than the wall of the right ventricle. This is because the left ventricle needs to be stronger than the right ventricle because it pumps blood around the whole body, whereas the right ventricle only pumps blood to the lungs.
2) Cardiac output = heart rate (bpm) x stroke volume
Cardiac output is the amount of blood pumped from the heart every minute.
Stroke volume is the volume of blood pumped out of the heart with every beat.
The ventricles of a larger heart are likely to have a greater volume than those in a smaller heart. This means that a person with a larger heart is likely to have a greater stroke volume than a person with a smaller heart. A greater stroke volume is likely to mean a greater cardiac output.
SB8e
1) Explain why organisms need to respire.
2) Recall the word equation for aerobic respiration.
3) Recall the word equation for anaerobic respiration in humans in humans and plants
1) Respiration results in the transfer of energy from glucose or food, which is used for important metabolic processes. Organisms require a constant supply of energy for: movement, keeping warm, producing and breaking down substances.
2) Glucose + oxygen —> carbon dioxide + water
C₆H₁₂O₆+ 6O₂ —> 6CO₂ + 6H₂O
3) In humans: glucose —> lactic acid
In plants: glucose —> ethanol + carbon dioxide
SB8e
1) What is respiration and explain why respiration is an exothermic process.
2) Compare aerobic and anaerobic respiration.
1) Respiration is a series of exothermic reactions that occur in the mitochondria of living cells in order to release energy from food molecules. Respiration is exothermic because it releases energy to the environment.
2) - Glucose is broken down in both aerobic and anaerobic respiration.
- Oxygen is broken down in only aerobic respiration.
- The products of aerobic respiration are carbon dioxide and water. An example of when a person may begin to respire anaerobically is during vigorous excercize.
- Both processes use glucose
- Both processes release energy for all the processes that occur in the body
- Aerobic respiration equation: oxygen + glucose —> carbon dioxide + water
- Anaerobic respiration equation: glucose —> lactic acid
SB8c
1) Recall the components and function of the circulatory system.
2) Recall the functions of the different types of blood vessels.
3) Describe the functions of the different types of blood cells (erythrocytes, phagocytes, lymphocytes).
1) In the circulatory system, blood flow away from the heart into arteries. These divide into narrow capillaries, which form networking through tissues. Blood returns to the heart in veins.
2) The arteries carry oxygenated blood away from the heart. It has thick walls to ensure that is doesn’t burst and become damaged under high pressure. The artery wall is elastic and can stretch as blood enters so that it can withstand the pressure. A high blood pressure, and a small lumen (hole in the centre of the vessel).
The veins carry deoxygenated blood towards the heart. It has thin walls, a very low blood pressure, and a large lumen (hole in the centre of the vessel). The veins contain valves to prevent back flow.
The capillaries carry both oxygenated and deoxygenated blood. It has very thin walls, a very low blood pressure, and a wide lumen for its size.
3) Erythrocytes (red blood cells) have no nucleus, so there is more space for haemoglobin. The cells are shaped like discs with a dimple in each side. This ‘biconcave’ shape allows a large surface area:volume ratio for oxygen to diffuse in and out.
Lymphocytes (white blood cells) remove foreign cells that get inside you. They produce proteins called antibodies that stick to foreign cells and help to destroy them.
Phagocytes (white blood cells) surround foreign cells and engulf them.
SB8c
1) Describe the functions of blood platelets and plasma.
2) Describe how the different blood vessels are adapted to their functions.
1) The platelets clot to prevent blood loss during an injury. Plasma carries dissolved substances such as glucose, carbon dioxide and urea.
2) Arteries carry blood away from the heart (usually oxygenated blood, except for the pulmonary artery). They have thick, muscular walls and a small lumen. This is in order to carry blood under high pressure.
Veins carry blood towards the heart (usually deoxygenated blood, except for the pulmonary vein). Veins have thin walls, a large lumen, and contain valves to prevent blood flowing the wrong way.
Capillaries allows diffusion of gases and nutrients from blood into the body cells. Capillaries have very thin, one cell thick walls. The walls are made of semi-permeable membrane to allow transport of gases and nutrients into and out of the blood.
SB8e - Core Practical
1) What is the aim of the respiration rates core practical?
2) What is the method for the respiration rates core practical?
1) Investigate the rate of respiration in living organisms.
2) A. Collect a tube with soda lime, held in place with cotton wool. The soda lime absorbs carbon dioxide. Soda lime is corrosive, so do not handle it. The cotton wool is there to protect you and the organisms.
B. Carefully collect some of the small organism in a weighing boat.
C. Gently shake the organisms out of the container and into the tube.
D. Insert the bung and capillary.
E. Set up a control tube.
F. Place both tube into a rack in a water bath at a set temperature. It is best to tilt the rack slightly so that the capillary tubes hang over the side of the water bath at an angle.
G. Wait for five minutes to let the organisms adjust to the temperature of the water bath.
H. Hold a beaker of coloured liquid to the ends of the capillary tubes, so that liquid enters.
I. Mark the position of coloured liquid in the tube and time for five minutes.
J. Mark the position of the coloured liquid again, and measure the distance in has travelled.
I. Repeat the experiment at different temperatures.
SB8e - Core Practical
1) What are the independent, dependent and control variables for the respiration rates core practical?
2) What are the safety hazards for the respiration rates core practical?
1) Independent variable: the temperature of the water bath.
Dependent variable: the distance the coloured liquid travels in the capillary tube.
Control variables include:
- The type and mass of organisms used.
- The duration of time for each measurement (five minutes).
- The size and material of the tube.
2) - Soda lime is corrosive. Wear eye protection.
- Do not touch the soda lime; use a spatula to position in the respirometer.
- Cotton wool bung prevents contact with soda lime. The cotton wool acts as a barrier, preventing direct contact between the experimenter’s skin and the lime, which can be corrosive.
- Do not inhale any dust.
SB8e - Core Practical
1) Explain why the blob of coloured liquid moves in the capillary tube.
2) Describe how you would set up a control tube, and explain why a control tube is necessary
3) Explain the lowest and highest temperature at which you would test the respiration rate in small organisms
1) Oxygen is used up; the carbon dioxide produced is absorbed by the soda lime; this reduces the pressure inside the tube and so the blob moves towards the tube.
2) The control tube would be exactly the same as the tube with the organisms but leaves the organisms out. A control tube is necessary to ensure that any movement of the coloured liquid is due to the presence of the organisms and not just due to the passage of time and/or the effect of temperature.
3) Not below freezing (since this may harm the cells of the maggots). Not above 40 °C (accept a range from 30–45 °C) since maggots are unlikely experience these temperatures in reality/their enzymes may start to denature/ may cause injury to the maggots.
SB8d
1) Why is the left ventricle of the human heart thicker than the right
2) Explain what will happen to the flow of blood in the heart if the valves do not work properly
1) This allows the left ventricle to pump blood around the body under high pressure.
2) The blood would flow backwards to a different chamber, or blood would leak through. Therefore, less oxygenated blood would be pumped to the body.
SB8e - Core Practical
1) Explain why the temperature should be kept the same in the respiration core practical
2) State and explain the role of soda lime in the experiment
1) The independent variable should be the only variable affecting the readings. Also, the temperature should be controlled so that the results are comparable.
2) The soda lime absorbs CO2 so the decrease in volume can be followed by the moving liquid as the oxygen is used up.
