This lesson covers:
- What respiration is and why it is important
- Aerobic respiration
- Anaerobic respiration in humans and microorganisms
What is respiration and why is it important?
Respiration is a chemical reaction that releases energy from the breakdown of glucose in cells.
It occurs in all living cells and is essential for providing energy for life processes like protein synthesis, muscle contraction and maintaining body temperature.
There are two main types of cellular respiration:
- Aerobic – This requires oxygen.
- Anaerobic – This does not require oxygen.
Aerobic respiration
Aerobic respiration:
- Occurs in mitochondria and uses oxygen.
- Releases a large amount of energy.
- Produces the waste products are carbon dioxide and water.
Overall word equation:
glucose + oxygen → carbon dioxide + water (+ energy)
Anaerobic respiration
Anaerobic respiration:
- Occurs in the cytoplasm.
- Releases less energy than aerobic respiration.
- Is used when oxygen levels are low.
- Has different waste products in different organisms.
Anaerobic respiration in humans
In humans, anaerobic respiration produces lactic acid.
This can build up in muscles during intense exercise leading to cramp and pain.
Overall word equation:
glucose → lactic acid (+ energy)
Anaerobic respiration in yeast
In yeast, anaerobic respiration produces carbon dioxide and ethanol (alcohol).
This process is called fermentation and is used to produce beers, wines, and bread.
Overall word equation:
glucose → carbon dioxide + ethanol (+ energy)
Practice Quiz
1. What is respiration and why is it important?
Answer: Respiration is a chemical reaction that releases energy from the breakdown of glucose in cells. It occurs in all living cells and is essential for providing energy for life processes like protein synthesis, muscle contraction, and maintaining body temperature.
2. What are the two main types of cellular respiration?
Answer: The two main types of cellular respiration are:
- Aerobic respiration: Requires oxygen.
- Anaerobic respiration: Does not require oxygen.
3. Where does aerobic respiration occur?
Answer: Aerobic respiration occurs in the mitochondria of cells.
4. What is the overall equation for aerobic respiration?
Answer: The overall word equation for aerobic respiration is:
5. What are the products of aerobic respiration?
Answer: The products of aerobic respiration are carbon dioxide, water, and a large amount of energy.
6. Why is aerobic respiration more efficient than anaerobic respiration?
Answer: Aerobic respiration is more efficient because it releases a larger amount of energy from glucose compared to anaerobic respiration.
7. Where does anaerobic respiration occur?
Answer: Anaerobic respiration occurs in the cytoplasm of cells.
8. What is the overall equation for anaerobic respiration in humans?
Answer: The overall word equation for anaerobic respiration in humans is:
9. What are the products of anaerobic respiration in humans?
Answer: The products of anaerobic respiration in humans are lactic acid and a small amount of energy.
10. What causes muscle cramps during intense exercise?
Answer: Muscle cramps during intense exercise are caused by the build-up of lactic acid in the muscles due to anaerobic respiration.
11. What is anaerobic respiration in yeast called?
Answer: Anaerobic respiration in yeast is called fermentation.
12. What are the products of anaerobic respiration in yeast?
Answer: The products of anaerobic respiration in yeast are carbon dioxide and ethanol (alcohol).
13. What is the overall equation for anaerobic respiration in yeast?
Answer: The overall word equation for anaerobic respiration in yeast is:
14. How is anaerobic respiration used in the production of alcoholic drinks?
Answer: Anaerobic respiration (fermentation) in yeast produces ethanol and carbon dioxide, which are used to make alcoholic drinks like beer and wine.
15. How is anaerobic respiration used in bread making?
Answer: In bread making, yeast ferments the sugars in the dough, producing carbon dioxide that makes the bread rise.
16. Why does anaerobic respiration release less energy than aerobic respiration?
Answer: Anaerobic respiration releases less energy because it does not fully break down glucose molecules compared to aerobic respiration, which completely oxidizes glucose to carbon dioxide and water.
17. What is the role of mitochondria in respiration?
Answer: Mitochondria are the sites of aerobic respiration, where glucose and oxygen are converted into energy, carbon dioxide, and water.
18. What happens to the lactic acid produced in muscles?
Answer: Lactic acid produced in muscles is transported to the liver, where it is converted back into glucose once oxygen is available.
19. Why do we breathe faster during exercise?
Answer: We breathe faster during exercise to increase oxygen intake and carbon dioxide removal, supporting increased aerobic respiration to meet the higher energy demands.
20. What is the difference between aerobic and anaerobic respiration?
Answer: Aerobic respiration requires oxygen and produces more energy, while anaerobic respiration does not require oxygen and produces less energy along with different waste products.
21. How do plants perform respiration?
Answer: Plants perform respiration similarly to animals, using glucose and oxygen to produce energy, carbon dioxide, and water in their mitochondria.
22. Can respiration occur without oxygen?
Answer: Yes, respiration can occur without oxygen through anaerobic respiration, which produces less energy and different waste products.
23. What are some examples of organisms that use anaerobic respiration?
Answer: Examples include yeast, certain bacteria, and muscle cells during intense exercise.
24. How is the energy produced in respiration used by cells?
Answer: The energy produced in respiration is used for various cellular activities, including protein synthesis, muscle contraction, cell division, and maintaining homeostasis.
25. What is the role of glucose in respiration?
Answer: Glucose is the primary fuel for respiration, providing the energy needed to produce ATP through its breakdown.
26. What is ATP, and why is it important?
Answer: ATP (adenosine triphosphate) is the energy currency of the cell, providing readily usable energy for various cellular processes.
27. How does oxygen support aerobic respiration?
Answer: Oxygen acts as the final electron acceptor in the electron transport chain, allowing for the complete oxidation of glucose and the production of a large amount of ATP.
28. What are the stages of aerobic respiration?
Answer: The stages of aerobic respiration include glycolysis, the Krebs cycle (citric acid cycle), and the electron transport chain.
29. What happens during glycolysis?
Answer: During glycolysis, one molecule of glucose is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH.
30. What is the Krebs cycle?
Answer: The Krebs cycle is a series of chemical reactions that further break down pyruvate into carbon dioxide, generating NADH, FADH₂, and ATP.
31. What is the electron transport chain?
Answer: The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane that transfer electrons from NADH and FADH₂ to oxygen, producing ATP.
32. How does lactic acid fermentation differ from alcoholic fermentation?
Answer: Lactic acid fermentation produces lactic acid and is used by muscle cells and some bacteria, while alcoholic fermentation produces ethanol and carbon dioxide and is used by yeast and some bacteria.
33. What is the role of NADH and FADH₂ in respiration?
Answer: NADH and FADH₂ are electron carriers that transport high-energy electrons to the electron transport chain, where their energy is used to produce ATP.
34. How does the body remove carbon dioxide produced in respiration?
Answer: Carbon dioxide is transported in the blood to the lungs, where it is exhaled during breathing.
35. Why is it important to remove carbon dioxide from the body?
Answer: Removing carbon dioxide is essential to prevent acidification of the blood, which can disrupt cellular functions and homeostasis.
36. What are some industrial applications of fermentation?
Answer: Industrial applications of fermentation include the production of alcoholic beverages, bread, biofuels, and certain pharmaceuticals.
37. How do anaerobic bacteria contribute to human health?
Answer: Anaerobic bacteria in the gut help with digestion, produce vitamins, and protect against harmful pathogens by maintaining a balanced microbiome.
38. What is the impact of oxygen debt after intense exercise?
Answer: Oxygen debt refers to the extra oxygen required after intense exercise to metabolize accumulated lactic acid and restore normal physiological conditions.
39. What is the significance of the Warburg effect in cancer cells?
Answer: The Warburg effect describes how cancer cells rely more on glycolysis for energy production even in the presence of oxygen, leading to high glucose consumption and lactic acid production.
40. How does cyanide affect respiration?
Answer: Cyanide inhibits the electron transport chain by binding to cytochrome c oxidase, preventing ATP production and leading to cellular and organismal death.
41. How do mitochondria adapt to increased energy demands?
Answer: Mitochondria can increase in number and efficiency through biogenesis, enhancing their ability to produce ATP during increased energy demands.
42. What is the role of myoglobin in muscle cells?
Answer: Myoglobin is a protein in muscle cells that stores oxygen, providing a readily available supply during intense exercise to support aerobic respiration.
43. How do high-altitude conditions affect respiration?
Answer: High-altitude conditions have lower oxygen levels, causing the body to adapt by increasing red blood cell production and enhancing the efficiency of oxygen transport and utilization.
44. What are the symptoms of lactic acidosis?
Answer: Symptoms of lactic acidosis include rapid breathing, nausea, vomiting, abdominal pain, and weakness, caused by the accumulation of lactic acid in the blood.
45. How does creatine supplementation affect muscle respiration?
Answer: Creatine supplementation increases the availability of phosphocreatine, providing a rapid source of ATP during short, intense bursts of exercise, enhancing performance and recovery.
46. How is respiration studied in the laboratory?
Answer: Respiration is studied using techniques like respirometry to measure oxygen consumption and carbon dioxide production, and biochemical assays to analyze enzyme activity and metabolic pathways.
47. What is oxidative phosphorylation?
Answer: Oxidative phosphorylation is the process by which ATP is produced in the mitochondria through the transfer of electrons from NADH and FADH₂ to oxygen by the electron transport chain.
48. What are the health benefits of regular aerobic exercise on respiration?
Answer: Regular aerobic exercise improves cardiovascular and respiratory efficiency, enhances oxygen uptake and utilization, and increases mitochondrial density and function.
49. How does hypoxia affect cellular respiration?
Answer: Hypoxia, or low oxygen levels, forces cells to rely more on anaerobic respiration, reducing ATP production and increasing lactic acid accumulation.
50. What are the evolutionary advantages of having both aerobic and anaerobic respiration?
Answer: Having both aerobic and anaerobic respiration allows organisms to survive and produce energy in varying environmental conditions, providing flexibility and resilience.