Aerobic Respiration B2.15 Miss Tagore

Learning Outcomes 2.1 recall that respiration is a process used by all living organisms that releases energy in organic molecules. 2.2 Explain how the human circulatory system facilitates respiration including: a. glucose and oxygen diffuses from capillaries into respiring cells b. Carbon dioxide diffuses from respiring cells into capillaries 2.3 Define diffusion as the movement of particles from an area of high concentration to an area of lower concentration 2.4 Demonstrate an understanding of how aerobic respiration uses oxygen to release energy from glucose and how this process can be modelled using the word equation for aerobic respiration

Diffusion Diffusion is the movement of molecules in a liquid or gas from high to low concentration until they are evenly spread out

Concentration Gradient high ground gradient (slope) low ground ball ball rolls down gradient ball stops

Concentration Gradient Like the ball on the slope, molecules always move down a gradient from high to low, until they are evenly spread out. http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/cells/cellsrev4.shtml Think about some everyday examples of diffusion – where have you seen/experienced them? Diffusion occurs in the human body all the time – why do you think this is?

Cells and diffusion The entry and exit of substances in and out of cells is called diffusion. This happens across the cell membrane. Animal cells take in glucose and oxygen by diffusion. Carbon dioxide and waste materials leave animal cells by diffusion.

Glucose + Oxygen Carbon Dioxide + Water http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/cells/cellsrev4.shtml Glucose + Oxygen Carbon Dioxide + Water http://www.youtube.com/watch?v=XTMYSGXhJ4E

You have millions of blood vessels feeding oxygen and glucose to all parts of your body. Without it, those parts of the body would die.

Summary Diffusion is the movement of gases or liquids moving from an area of high concentration to an area of lower concentration. Glucose and oxygen are taken in to the body, where they diffuse into our cells. Glucose and oxygen are essential for our cells to live. Carbon dioxide and water are the waste products that we breathe out. Carbon dioxide and oxygen diffuse in the opposite direction – they come from all of our cells and eventually move to the lungs where they are breathed out.

8 Multiple choice questions Quick Test 8 Multiple choice questions

Question 1 1. Substances enter and leave cells by the process of A dissolving B evaporating C breathing D diffusing

Question 2 2. Substances enter and leave cells by passing through the   A nucleus B membrane C cytoplasm D vacuole

Question 3 3. In diffusion, substances move from   A high concentration to low concentration B high concentration to high concentration C low concentration to low concentration D low concentration to high concentration

Question 4 4. Diffusion stops when molecules A are at high concentration B are a low concentration C are at even concentration D stop moving completely

Question 5 5. In which diagram do the black molecules have the highest concentration?

Question 6 6. The diagram shows the concentrations of black molecules in four cells In which direction will the black molecules diffuse? A From cell 1 to cell 2 B From cell 2 to cell 4 C From cell 4 to cell 3 D From cell 3 to cell 1

Question 7 7. Carbon dioxide, oxygen, and dissolved food are important substances in the body. Which of these enter or leave cells by the process of diffusion? A carbon dioxide only B carbon dioxide and dissolved food only C oxygen and dissolved food only D oxygen, carbon dioxide, and dissolved food

Question 8 8. Diffusion is important to mammals. One reason is that A they breathe by diffusion B oxygen enters their blood by diffusion C blood moves by diffusion D carbon dioxide enters their cells by diffusion

Aerobic Respiration 2.4 Demonstrate an understanding of how aerobic respiration uses oxygen to release energy from glucose and how this process can be modelled using the word equation for aerobic respiration

Food & Energy RESPIRATION We know that the body needs energy from food in order to move, keep warm and grow The chemical process by which this energy is released from cells is called RESPIRATION

Food & Energy The main energy source in a cell is GLUCOSE Glucose is obtained by plants during photosynthesis and animals through feeding

Respiration Glucose has to be broken down to release its energy The chemical energy in glucose is released in a series of enzyme controlled steps Some energy is lost as heat energy The chemical energy is not used directly by the cell but is stored through the formation of a molecule called ATP http://www.bbc.co.uk/schools/gcsebitesize/science/videos/aerobic_video1.shtml

Body Functions e.g. Muscle contraction Energy Summary Chemical energy that we take in through food is called… Glucose Chemical energy is released This process is controlled by enzymes of Breakdown Glucose Some of the chemical energy is lost as heat energy e.g. When the body moves Body Functions e.g. Muscle contraction

What is ATP? ATP or Adenosine triphosphate is a high-energy molecule that stores the energy we need to do just about everything ATP is the energy source for: Muscle contraction Cell division Building up (synthesis) of proteins Transmission of nerve impulses

Summary Notes Respiration is a chemical process in which energy is released from food molecules in cells The cell’s main energy source is glucose Energy is released from glucose using a series of enzymes to control each stage of the breakdown process Enzymes are needed so that our cells do not use all their energy at once or release it too slowly

Summary Notes Energy from food is converted into the form of ATP. ATP is the energy source for: Muscle contraction Cell division Building up (synthesis) of proteins Transmission of nerve impulses

Quick Questions

Question 1 Farm animals that do not move around that much do not need a lot of food – why do you think this is?

Question 2 Glucose and oxygen are needed for aerobic respiration to occur. Which of these two molecules contains the energy that is released in respiration?

Describe two processes inside cells that require energy to occur. Question 3 Describe two processes inside cells that require energy to occur.

Answer 1 We need energy from food to move. If an animal does not move that much, it will not require a lot of energy, so will not eat a lot of food.

Glucose contains the energy. Answer 2 Glucose contains the energy.

Answer 3 Any 2 from: Cell division Muscle contraction Nerve transmission Building proteins.

Investigating the effects of exercise

Effect of Exercise When you exercise, your muscles need lots of energy. The energy comes from aerobic respiration which needs oxygen and glucose. This reaction produces carbon dioxide as a waste product. We breathe in oxygen and breathe out carbon dioxide all day every day. When we exercise, our breathing rate and heart rate are increased.

Investigating breathing rate and heart rate Consider the following questions: Why does our breathing rate increase during exercise? Why does our heart rate increase during exercise? What type of exercise do you think would increase breathing rate and heart rate?

Pulse The number of times that your heart beats in one minute (BPM). The diagram shows the three main locations for a pulse. Pulse is found in arteries. These are blood vessels that take blood away from the heart – they carry blood at a greater force, which is why you feel a pulse here and not in veins.

Beats per minute (15 secs x 4) Resting Heart Rate Find your own resting heart rate Beats per 15 seconds Beats per minute (15 secs x 4) 1 2 3 Average

Investigating Pulse Rate Think about how you would conduct an investigation to record pulse rate before and after an activity. Think about what activity you could easily do in the lab How could you make your experiment reliable? What would need to be kept the same (controlled variable)? What would need to be different (independent variable)? What are you trying to measure (dependent variable)? How are you going to record your data and present it to spot any trends?

Extension If you have successfully designed and completed an experiment on pulse rate, think about how you would measure breathing rate. Breathing rate is the number of breaths you take in one minute. A breath is counted as one inspiration and one expiration, or breathing in and out. What do you think would happen to your breathing rate when you do strength exercises vs cardiovascular exercises?

Anaerobic Respiration http://www.bbc.co.uk/learningzone/clips/sport-science/10885.html

Anaerobic Respiration The more active a cell is, the more energy it uses up at a faster rate. During exercise, the muscles use up oxygen at a faster rate than normal, so the blood supply to muscles is greater to cope with the demand. The volume of blood circulated by the heart depends not only on heart rate, but also the volume of blood that the heart can pump out in one beat. This is known as stroke volume.

The volume of blood pumped out of the heart on each beat. Stroke Volume The volume of blood pumped out of the heart on each beat.

Stroke volume x heart rate = cardiac output To find out the total volume of blood that circulates round the heart at any given time, we do the following sum: Stroke volume x heart rate = cardiac output

Exercise Heart rate and stroke volume increase with exercise. This means cardiac output will also increase with exercise. We have to make sure that the blood is carrying enough oxygen to supply working muscles to cope with the oxygen demand. Because of this, breathing rate also increases.

Stroke volume x heart rate = cardiac output Summary Exercise increases the body’s demand for glucose and oxygen. The heart rate increases to pump more blood around the body quickly. The volume of blood that is ejected from the heart in one beat is called stroke volume. The total volume of blood that circulates round the heart at any given time is called the cardiac output. This is calculated by: Stroke volume x heart rate = cardiac output There is an increase in breathing rate to ensure that enough oxygen diffuses into the blood to supply working muscles.

Anaerobic respiration & lactic acid When exercising intensely, we cannot supply oxygen to our muscles fast enough. In this case, glucose is broken down to release energy in a different, less efficient way. This does not require oxygen and releases much less energy. This is called anaerobic respiration.

Anaerobic respiration & lactic acid Anaerobic respiration releases much less energy than aerobic respiration and glucose is converted to lactic acid. After exercise, lactic acid can be broken down to carbon dioxide and water, but oxygen is required to do this. Breathing rate and heart rate still remain high after a period of exercise so that additional oxygen can be obtained by cells. This period of recovery is called excess post-exercise oxygen consumption (EPOC) (used to be known as the oxygen debt). Pulse rate and breathing rate will return to normal once this period of oxygen consumption is over. The time taken to return to normal is the recovery period.

Summary In the absence of oxygen, glucose is not fully broken down to carbon dioxide and water. Instead, anaerobic respiration occurs. This means that very little oxygen is present and glucose is converted to lactic acid. This is a much less efficient process and so less energy is released. After exercise, lactic acid is converted to carbon dioxide and water, when oxygen is present. We continue to breathe faster and have a higher heart rate after exercise because of a requirement for additional oxygen. This is called excess post-exercise oxygen consumption (EPOC). The time taken for breathing rate and heart rate to return to normal after a period of exercise is called recovery time.

Your tasks Collect a textbook and complete questions 1 – 8 on pages 60 and 61. Any questions that you do not finish will result in you staying in over break. Once you have completed this, collect puzzle cards.

Answers to textbook questions HR and BR increase during exercise (a) CO = SV x HR (b) 60 x 76 = 4560 160x105= 16800 Difference = 12240 Glucose + oxygen carbon dioxide + water + energy Glucose  Lactic acid+ energy 4. Oxygen need does not stop after exercise because lactic acid must be broken down. 5. Deeper breathes will allow you to take in more oxygen much quicker than taking shallow breaths. 6. The energy needs for the heart will be greater as it will be pumping more blood at a faster rate. 7. “Excess post-exercise oxygen consumption (EPOC) is used to break down lactic acid into carbon dioxide and water” 8. Sprinting requires much more energy and will therefore need more glucose and oxygen to maintain this for a longer length of time. Because our bodies run out of oxygen when demand is high, sprinting for a long time is not sustainable or possible.