10.1 Respiration
- Describe respiration as the chemical reactions in all living cells that release energy from glucose?
- Respiration is a series of chemical reactions that take place within all living cells.
- It’s a process that breaks down glucose, a sugar molecule, to release energy.
- This energy is stored in a molecule called ATP (adenosine triphosphate), which can be used to power various cellular activities
Think of respiration like burning fuel to get energy. The glucose is the fuel, and the energy released is used to power the cell’s functions, such as moving, growing, and repairing itself.
- State the uses of energy in living organisms including muscle contraction, protein synthesis, cell division,active transport, growth, the passage of electrical impulses along neurones and the maintenance of a constant body temperature?
Energy is essential for all living organisms to perform various vital functions. Here are some key uses of energy:
- Muscle Contraction:
- Energy is required for the movement of muscles, enabling organisms to perform actions like walking, running, and lifting objects.
- Protein Synthesis:
- The process of building proteins, which are essential for various cellular functions, requires energy.
- Cell Division:
- Energy is needed for cells to replicate and divide, allowing organisms to grow and reproduce.
- Active Transport:
- Energy is used to move substances across cell membranes against their concentration gradient, a process known as active transport. This is crucial for maintaining cellular balance.
- Growth:
- Energy is required for the growth and development of organisms, as cells need energy to produce new tissues and structures.
Passage of Electrical Impulses Along Neurons:
- Energy is used to generate and transmit electrical signals along neurons, allowing organisms to sense their environment, process information, and respond accordingly.
- Maintenance of a Constant Body Temperature:
- Energy is used to generate heat, which helps maintain a constant body temperature in organisms that regulate their internal environment.
- Investigate and describe the effect of temperature on respiration in yeast
Temperature increases the respiration rate in yeast up to a certain point, after which it can inhibit or kill the yeast.
Yeast, like many other organisms, relies on a process called respiration to produce energy. This process involves the breakdown of glucose to produce carbon dioxide and water, releasing energy in the process. The rate at which this process occurs is heavily influenced by temperature. As the temperature increases, the kinetic energy of the yeast cells also increases, causing them to move and react more quickly. This results in an increased rate of respiration, and therefore, more energy production.
However, this increase in respiration rate only occurs up to a certain temperature, known as the optimum temperature. For yeast, this is typically around 35°C. Beyond this temperature, the rate of respiration begins to decrease. This is because the high temperatures start to denature the enzymes involved in the respiration process. Enzymes are proteins that speed up chemical reactions, and they are crucial for respiration. When they are denatured, their structure changes and they can no longer function effectively, slowing down the respiration process.
10.2 Aerobic respiration
- Describe aerobic respiration as the release of a relatively large amount of energy by the breakdown of glucose in the presence of oxygen?
Aerobic respiration is a process that occurs in the presence of oxygen. It involves the breakdown of glucose molecules into carbon dioxide and water, releasing a relatively large amount of energy. This energy is stored in the form of ATP (adenosine triphosphate), which can be used to power various cellular activities.
Think of aerobic respiration like burning wood in a fire. The wood (glucose) is broken down with the help of oxygen, releasing heat and light (energy) in the form of flames.
- State the word equation and balanced chemical equation for aerobic respiration?
Word Equation for Aerobic Respiration
Glucose + Oxygen → Carbon dioxide + Water + Energy
Balanced Chemical Equation for Aerobic Respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
- C6H12O6: Glucose
- 6O2: Oxygen
- 6CO2: Carbon dioxide
- 6H2O: Water
- ATP: Adenosine triphosphate (energy)
10.3 Anaerobic respiration
- Describe anaerobic respiration as the release of a relatively small amount of energy by the breakdown of glucose without using oxygen?
Anaerobic respiration is a process that occurs in the absence of oxygen. It also involves the breakdown of glucose, but it releases a relatively small amount of energy compared to aerobic respiration. The end products of anaerobic respiration can vary depending on the organism, but they typically include carbon dioxide and either lactic acid or alcohol.
Think of anaerobic respiration like burning wood without enough oxygen. The wood still burns, but it produces less heat and smoke (energy) and may leave behind unburned charcoal.
- State the word equation for anaerobic respiration in humans?
Word Equation for Anaerobic Respiration in Humans:
Glucose → Lactic acid + Energy
In humans, when oxygen is limited, glucose is broken down through anaerobic respiration, producing lactic acid and a smaller amount of energy compared to aerobic respiration.
- State the word equation for anaerobic respiration in yeast?
Word Equation for Anaerobic Respiration in Yeast:
Glucose → Ethanol + Carbon dioxide + Energy
In yeast, when oxygen is limited, glucose is broken down through anaerobic respiration, producing ethanol (alcohol), carbon dioxide, and a smaller amount of energy compared to aerobic respiration.
- Explain why lactic acid builds up in muscles and blood during vigorous exercise causing Excess Post exercise Oxygen Consumption (EPOC) or an ‘oxygen debt’?
Lactic Acid Build-Up and EPOC
During vigorous exercise, our muscles require a significant amount of oxygen to produce energy through aerobic respiration. However, when the demand for oxygen exceeds the supply, our bodies resort to anaerobic respiration. This process breaks down glucose without oxygen, producing lactic acid as a byproduct.
Lactic acid build-up in muscles and blood can lead to muscle fatigue, soreness, and a burning sensation. The accumulation of lactic acid can also lower the pH of the blood, causing acidosis.
Excess Postexercise Oxygen Consumption (EPOC), or “oxygen debt,” is the body’s attempt to repay this oxygen deficit. After exercise, the body continues to breathe heavily to take in more oxygen. This extra oxygen is used to:
- Convert Lactic Acid to Glucose:
A portion of the accumulated lactic acid is converted back into glucose through a process called the Cori cycle, which occurs primarily in the liver.
- Replenish Oxygen Stores:
The body replenishes its depleted oxygen stores in the muscles and blood.
- Restore ATP Levels:
ATP, the energy currency of cells, is resynthesized using the oxygen available.
- Remove Waste Products:
The body eliminates waste products, such as carbon dioxide, that were produced during anaerobic respiration.
By repaying the oxygen debt, the body restores its energy balance and prepares for future physical activity.
- Outline how the oxygen debt is removed after exercise, limited to:
(a) continuation of fast heart rate to transport lactic acid in blood from muscles to the liver
(b) continuation of deeper and faster breathing to supply oxygen for the breakdown of lactic acid in the
Liver
Removing the Oxygen Debt After Exercise
After intense exercise, the body experiences an “oxygen debt” due to the accumulation of lactic acid in the muscles. To repay this debt, the body continues to breathe heavily and maintain a fast heart rate for a period of time.
- a) Continuation of Fast Heart Rate:
- Transport of Lactic Acid:
A rapid heart rate increases blood flow, which helps to transport lactic acid from the muscles to the liver.
- Oxygen Delivery:
The increased blood flow also ensures a steady supply of oxygen to the liver, which is essential for the breakdown of lactic acid.
- b) Continuation of Deeper and Faster Breathing:
- Oxygen Supply:
Deeper and faster breathing increases the intake of oxygen, providing the necessary oxygen for the breakdown of lactic acid in the liver.
- Carbon Dioxide Removal:
The increased breathing also helps to remove carbon dioxide, a waste product of metabolism, from the body.
By continuing to breathe heavily and maintain a fast heart rate after exercise, the body can effectively remove the oxygen debt and restore its energy balance.