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External Respiration
One method for obtaining Oxygen from the Environment is through external respiration or breathing. In animal organisms, the process of external respiration is performed in a number of different ways. Animals that lack specialized organs for respiration rely on diffusion across external tissue surfaces to obtain oxygen. Others either have organs specialized for gas exchange or have a complete Respiratory System. In organisms, such as nematodes (roundworms), gases and nutrients are exchanged with the external environment by diffusion across the surface of the animals body. Insects and spiders have respiratory organs called tracheae, while fish have gills as sites for gas exchange. Humans and other mammals have a respiratory system with specialized respiratory organs (lungs) and Tissues. In the human body, oxygen is taken into the lungs by inhalation and carbon dioxide is expelled from the lungs by exhalation. External respiration in mammals encompasses the mechanical processes related to breathing. This includes contraction and relaxation of the diaphragm and accessory muscles, as well as breathing rate.
Internal Respiration
External respiratory processes explain how oxygen is obtained, but how does oxygen get to body cells? Internal respiration involves the transportation of gases between the blood and body tissues. Oxygen within the lungs diffuses across the thin epithelium of lung alveoli (air sacs) into surrounding capillaries containing oxygen depleted blood. At the same time, carbon dioxide diffuses in the opposite direction (from the blood to lung alveoli) and is expelled. Oxygen rich blood is transported by the Circulatory System from lung capillaries to body cells and tissues. While oxygen is being dropped off at cells, carbon dioxide is being picked up and transported from tissue cells to the lungs.
Cellular Respiration
The oxygen obtained from internal respiration is used by cells in cellular respiration. In order to access the energy stored in the foods we eat, biological Molecules composing foods (Carbohydrates, proteins, etc,) must be broken down into forms that the body can utilize. This is accomplished through the digestive process where food is broken down and nutrients are absorbed into the blood. As blood is circulated throughout the body, nutrients are transported to body cells. In cellular respiration, glucose obtained from digestion is split into its constituent parts for the production of energy. Through a series of steps, glucose and oxygen are converted to carbon dioxide (CO2), water (H2O), and the high energy molecule adenosine triphosphate (ATP). Carbon dioxide and water formed in the process diffuse into the interstitial fluid surrounding cells. From there, CO2 diffuses into blood plasma and red blood cells. ATP generated in the process provides the energy needed to perform normal cellular functions, such as macromolecule synthesis, muscle contraction, cilia and flagella movement, and cell division.
Aerobic Respiration
Aerobic cellular respiration consists of three stages: glycolysis, citric acid cycle (Krebs Cycle), and electron transport with oxidative phosphorylation.
Glycolysis occurs in the cytoplasm and involves the oxidation or splitting of glucose into pyruvate. Two molecules of ATP and two molecules of the high energy NADH are also produced in glycolysis. In the presence of oxygen, pyruvate enters the inner matrix of cell mitochondria and undergoes further oxidation in the Krebs cycle.
Krebs Cycle: Two additional molecules of ATP are produced in this cycle along with CO2, additional protons and electrons, and the high energy molecules NADH and FADH2. Electrons generated in the Krebs cycle move across the folds in the inner membrane (cristae) that separate the mitochondrial matrix (inner compartment) from the intermembrane space (outer compartment). This creates an electrical gradient, which helps the the electron transport chain pump hydrogen protons out of the matrix and into the intermembrane space.
The electron transport chain is a series of electron carrier protein complexes within the mitochondrial inner membrane. NADH and FADH2 generated in the Krebs cycle transfer their energy in the electron transport chain to transport protons and electrons to the intermembrane space. The high concentration of hydrogen protons in the intermembrane space is utilized by the protein complex ATP synthase to transport protons back into the matrix. This provides the energy for the phosphorylation of ADP to ATP. Electron transport and oxidative phosphorylation account for the formation of 34 molecules of ATP.
In total, 38 ATP molecules are produced by prokaryotes in the oxidation of a single glucose molecule. This number is reduced to 36 ATP molecules in eukaryotes, as two ATP are consumed in the transfer of NADH to mitochondria.
Anaerobic Respiration
How do extremophiles like some bacteria and archaeans survive in environments without oxygen? The answer is by anaerobic respiration. This type of respiration occurs without oxygen and involves the consumption of another molecule (nitrate, sulfur, iron, carbon dioxide, etc.) instead of oxygen. Unlike in Fermentation-2/”>Fermentation, anaerobic respiration involves the formation of an electrochemical gradient by an electron transport system that results in the production of a number of ATP molecules. Unlike in aerobic respiration, the final electron recipient is a molecule other than oxygen. Many anaerobic organisms are obligate anaerobes; they don't perform oxidative phosphorylation and die in the presence of oxygen. Others are facultative anaerobes and can also perform aerobic respiration when oxygen is available.
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Aerobic respiration
Aerobic respiration is a metabolic pathway that uses oxygen to produce energy. It is the most efficient way to produce energy, and it is the primary pathway used by most cells. Aerobic respiration takes place in the mitochondria of cells.
The first step in aerobic respiration is glycolysis. Glycolysis is a series of reactions that break down glucose into pyruvate. In glycolysis, two ATP molecules are produced, and two NADH molecules are produced.
The next step in aerobic respiration is the Krebs cycle. The Krebs cycle is a series of reactions that take place in the mitochondrial matrix. In the Krebs cycle, pyruvate is converted into acetyl-CoA. Acetyl-CoA is then used to produce ATP, NADH, and FADH2.
The final step in aerobic respiration is oxidative phosphorylation. Oxidative phosphorylation is a series of reactions that take place in the inner mitochondrial membrane. In oxidative phosphorylation, ATP is produced using the energy from NADH and FADH2.
Anaerobic respiration
Anaerobic respiration is a metabolic pathway that does not use oxygen to produce energy. It is less efficient than aerobic respiration, but it can be used by cells in environments where oxygen is not available. Anaerobic respiration takes place in the cytoplasm of cells.
The most common type of anaerobic respiration is fermentation. Fermentation is a series of reactions that break down glucose into pyruvate. In fermentation, two ATP molecules are produced, but no NADH or FADH2 are produced.
Fermentation
Fermentation is a metabolic process that produces energy in the absence of oxygen. It is used by many different organisms, including bacteria, yeast, and some Plants. There are many different types of fermentation, but they all involve the breakdown of glucose to produce ATP.
The most common type of fermentation is alcoholic fermentation. In alcoholic fermentation, glucose is converted into ethanol and carbon dioxide. This type of fermentation is used by yeast to produce alcohol.
Another type of fermentation is lactic acid fermentation. In lactic acid fermentation, glucose is converted into lactic acid. This type of fermentation is used by muscle cells when they are working hard and there is not enough oxygen available.
External respiration
External respiration is the exchange of gases between the blood and the environment. It takes place in the lungs. The lungs are located in the chest cavity. They are made up of millions of tiny air sacs called alveoli. The alveoli are surrounded by capillaries.
The blood carries oxygen from the lungs to the tissues. The oxygen diffuses from the alveoli into the capillaries. The carbon dioxide from the tissues diffuses from the capillaries into the alveoli. The carbon dioxide is then exhaled out of the lungs.
Internal respiration
Internal respiration is the exchange of gases between the cells and the blood. It takes place in the mitochondria of cells. The mitochondria are the energy-producing organelles in cells.
The blood carries oxygen from the lungs to the mitochondria. The oxygen diffuses from the blood into the mitochondria. The carbon dioxide from the mitochondria diffuses from the mitochondria into the blood. The carbon dioxide is then carried by the blood to the lungs, where it is exhaled out of the body.
Aerobic respiration
What is aerobic respiration?
Aerobic respiration is a metabolic pathway that uses oxygen to produce energy. It is the most efficient way to produce energy, and it is the primary way that cells produce energy in the presence of oxygen.What are the steps of aerobic respiration?
The steps of aerobic respiration are glycolysis, pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation.What are the products of aerobic respiration?
The products of aerobic respiration are carbon dioxide, water, and ATP.What is the role of oxygen in aerobic respiration?
Oxygen is the final electron acceptor in the electron transport chain. It is used to reduce NAD+ to NADH, which is then used to produce ATP in oxidative phosphorylation.What is the importance of aerobic respiration?
Aerobic respiration is the most efficient way to produce energy. It is the primary way that cells produce energy in the presence of oxygen.
Anaerobic respiration
What is anaerobic respiration?
Anaerobic respiration is a metabolic pathway that does not use oxygen to produce energy. It is a less efficient way to produce energy than aerobic respiration, but it is the only way that cells can produce energy in the absence of oxygen.What are the steps of anaerobic respiration?
The steps of anaerobic respiration vary depending on the organism. In humans, the most common form of anaerobic respiration is glycolysis.What are the products of anaerobic respiration?
The products of anaerobic respiration vary depending on the organism. In humans, the products of glycolysis are pyruvate, lactate, and ATP.What is the role of oxygen in anaerobic respiration?
Oxygen is not used in anaerobic respiration.What is the importance of anaerobic respiration?
Anaerobic respiration is important for organisms that live in environments where oxygen is not available. It is also important for organisms that need to produce energy quickly, such as during exercise.
Cellular respiration
What is cellular respiration?
Cellular respiration is the process by which cells produce energy. It is a complex process that involves many steps.What are the stages of cellular respiration?
The stages of cellular respiration are glycolysis, pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation.What are the products of cellular respiration?
The products of cellular respiration are carbon dioxide, water, and ATP.What is the role of oxygen in cellular respiration?
Oxygen is the final electron acceptor in the electron transport chain. It is used to reduce NAD+ to NADH, which is then used to produce ATP in oxidative phosphorylation.What is the importance of cellular respiration?
Cellular respiration is the process by which cells produce energy. It is a vital process that all cells need to survive.
Question 1
Which of the following is not a type of respiration?
(A) Aerobic respiration
(B) Anaerobic respiration
(C) Photosynthesis
(D) Fermentation
Answer
(C) Photosynthesis is a process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen. It is not a type of respiration.
Question 2
Aerobic respiration occurs in the presence of oxygen. Which of the following is not a product of aerobic respiration?
(A) Carbon dioxide
(B) Water
(C) ATP
(D) Heat
Answer
(A) Carbon dioxide is a product of both aerobic and anaerobic respiration.
Question 3
Anaerobic respiration occurs in the absence of oxygen. Which of the following is not a product of anaerobic respiration?
(A) Lactic acid
(B) Ethanol
(C) ATP
(D) Heat
Answer
(C) ATP is a product of both aerobic and anaerobic respiration.
Question 4
Fermentation is a type of anaerobic respiration. Which of the following is not a product of fermentation?
(A) Lactic acid
(B) Ethanol
(C) ATP
(D) Carbon dioxide
Answer
(C) ATP is a product of both aerobic and anaerobic respiration.
Question 5
Which of the following is the most efficient type of respiration?
(A) Aerobic respiration
(B) Anaerobic respiration
(C) Photosynthesis
(D) Fermentation
Answer
(A) Aerobic respiration is the most efficient type of respiration because it produces the most ATP.
Question 6
Which of the following is the least efficient type of respiration?
(A) Aerobic respiration
(B) Anaerobic respiration
(C) Photosynthesis
(D) Fermentation
Answer
(D) Fermentation is the least efficient type of respiration because it produces the least ATP.
Question 7
Which of the following is the process by which cells break down glucose to produce ATP?
(A) Respiration
(B) Photosynthesis
(C) Fermentation
(D) Glycolysis
Answer
(A) Respiration is the process by which cells break down glucose to produce ATP.
Question 8
Which of the following is the process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen?
(A) Respiration
(B) Photosynthesis
(C) Fermentation
(D) Glycolysis
Answer
(B) Photosynthesis is the process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen.
Question 9
Which of the following is the process by which yeast converts glucose into ethanol and carbon dioxide?
(A) Respiration
(B) Photosynthesis
(C) Fermentation
(D) Glycolysis
Answer
(C) Fermentation is the process by which yeast converts glucose into ethanol and carbon dioxide.
Question 10
Which of the following is the process by which cells break down glucose into pyruvate?
(A) Respiration
(B) Photosynthesis
(C) Fermentation
(D) Glycolysis
Answer
(D) Glycolysis is the process by which cells break down glucose into pyruvate.