Respiration and Energy Transfer
Can you recall? Page No. 151
1. Which nutrients are used for energy production?
Answer: Carbohydrates, proteins, and fats are used for energy production.
2. Which is most preferred nutrient among carbohydrate, protein and fat for energy production? Why?
Answer: Carbohydrates, particularly glucose, are the most preferred nutrient for energy production because they are rapidly broken down in glycolysis, providing quick energy.
3. Why do organisms take up oxygen and release carbon dioxide?
Answer: Organisms take up oxygen to act as the terminal electron acceptor in aerobic respiration, oxidizing substrates to produce energy, and release carbon dioxide as a byproduct of this oxidation.
4. What is aerobic and anaerobic respiration?
Answer: Aerobic respiration uses oxygen to completely oxidize glucose, producing up to 38 ATP, while anaerobic respiration (fermentation) occurs without oxygen, partially oxidizing glucose to produce only 2 ATP.
5. Which steps are involved in aerobic respiration?
Answer: Aerobic respiration involves glycolysis, pyruvate oxidation (conversion to Acetyl CoA), Krebs cycle, electron transport chain, and terminal oxidation.
Use your brain power Page No. 152
1. What is the role of Mg⁺⁺, Zn⁺⁺ in various steps of glycolysis?
Answer: Mg⁺⁺ acts as a cofactor for enzymes like hexokinase and phosphofructokinase in glycolysis, stabilizing phosphate groups during phosphorylation, while Zn⁺⁺ may assist in enzyme activity.
Explanation: The document highlights Mg⁺⁺ as a cofactor in steps involving hexokinase (step 1), phosphofructokinase (step 3), phosphoglycerate kinase (step 7), enolase (step 9), and pyruvate kinase (step 10) of glycolysis. Zn⁺⁺ is not explicitly mentioned, but it may support enzyme function in some organisms, as inferred from general biochemical knowledge.
2. Why some reactions of glycolysis are reversible and some irreversible?
Answer: Some glycolysis reactions, like isomerization (e.g., glucose-6-phosphate to fructose-6-phosphate), are reversible due to low energy barriers, while phosphorylation reactions (e.g., by hexokinase and phosphofruct kinase) are irreversible because they involve significant energy input from ATP.
3. Why is glycolysis considered as biochemical proof of evolution?
Answer: Glycolysis is considered biochemical proof of evolution because it is a universal metabolic pathway present in nearly all living organisms, suggesting a common evolutionary origin.
4. Why do athletes like sprinters have higher proportion of white muscle fibers?
Answer: Sprinters have a higher proportion of white muscle fibers because these fibers rely on glycolysis for rapid, high-energy production needed for short, intense bursts of activity, despite accumulating lactic acid.
Internet my friend Page No. 155
What is effect of carbon monoxide poisoning on cytochromes?
Answer: The document does not explicitly describe the effect of carbon monoxide (CO) poisoning on cytochromes. However, based on standard biological knowledge and the context of the electron transport chain (ETC) discussed in the document, carbon monoxide can bind to cytochrome c oxidase (complex IV) in the ETC, inhibiting its ability to transfer electrons to oxygen. This disrupts terminal oxidation, halting ATP production and causing cellular energy failure.
Explanation: The document details that complex IV (cytochrome c oxidase) is responsible for transferring electrons to molecular oxygen, forming water. While CO poisoning is not directly addressed, its known effect is to block this process, leading to respiratory failure.
Use your brain power Page No. 157
Do the plants breath like animals? If yes, how and why?
Answer: Yes, plants respire like animals by oxidizing glucose in mitochondria to produce ATP, releasing CO₂, primarily to meet energy demands for growth and metabolism.
Explanation: The document does not directly answer this question but implies that respiration is a universal process in living organisms. Plants perform aerobic respiration in mitochondria, using oxygen to break down glucose (via glycolysis, Krebs cycle, and ETC) for energy, similar to animals. This is necessary for cellular processes like growth, nutrient transport, and maintenance, especially in non-photosynthetic tissues.
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