41 public questions tagged with this topic.
Fermentation occurs in the absence of oxygen and does not involve the Electron Transport Chain. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Morphology and Anatomy of Flowering Plants, Topic: Plant structure and tissue systems.
Hexokinase catalyzes the phosphorylation of glucose to glucose-6-phosphate, an irreversible step in glycolysis. This follows from NCERT principle where relation explains outcome clearly for students.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept, Topic: Plant structure, physiology and applications.
Glycolysis occurs in the cytoplasm and is the first step in both aerobic and anaerobic respiration. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Morphology and Anatomy of Flowering Plants, Topic: Plant structure and tissue systems.
Leptin, secreted by adipose tissue, signals the brain to reduce hunger and regulate body weight. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Structural Organisation in Animals and Frog, Topic: Tissues, skeletal and organ systems.
NAD⁺ is reduced to NADH during glycolysis and the Krebs cycle, playing a crucial role in llular respiration. This follows from NCERT principle where relation explains outcome clearly for students.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept, Topic: Plant structure, physiology and applications.
Glucose is the primary substrate for respiration, undergoing glycolysis to produce ATP. This follows from NCERT principle where relation explains outcome clearly for students.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept, Topic: Plant structure, physiology and applications.
Citric acid is the first stable compound formed when Acetyl-CoA combines with oxaloacetic acid in the Krebs cycle. This follows from NCERT principle where relation explains outcome clearly for students.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept, Topic: Plant structure, physiology and applications.
Vitamin B3 (Niacin) is a key component of NAD (Nicotinamide Adenine Dinucleotide). This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Biology - Zoology portion covering relevant system and function.
Vitamin B₁ (Thiamine), as part of TPP, aids in the decarboxylation of pyruvate to acetyl-CoA.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Vitamins - Types, Coenzymes and Deficiency Diseases - Part 2
Beta-carotene is tetraterpenoid C40 carotenoid consisting of two beta-ionone rings linked by eleven conjugated double bonds providing strong antioxidant scavenging singlet oxygen and light filtering. Most importantly it serves as provitamin A carotenoid because symmetrical cleavage at central 15,15' double bond by enzyme beta-carotene 15,15'-monooxygenase BCMO1 in intestinal enterocytes and hepatic stellate cells yields two molecules of retinaldehyde. Retinal can be reduced to retinol bound to retinol binding protein for systemic transport to retina for rhodopsin regeneration mediating scotopic vision, oxidized to retinoic acid activating gene transcription via nuclear receptors RAR and RXR heterodimers regulating embryonic development, epithelial differentiation, immune cell maturation, and spermatogenesis. Humans cannot synthesize carotenoid backbone requiring dietary intake. Vitamin A deficiency leads to xerophthalmia, night blindness, keratomalacia, impaired mucosal immunity increased measles mortality. Beta-carotene bioavailability enhanced by dietary lipids and food processing releasing crystalline aggregates, with conversion factor 12:1 to retinol activity equivalents in mixed diet.
Ref: Lodish Molecular Cell Biology Vitamins; NIH StatPearls Beta-carotene Vitamin A; Olson 1989.
Archaea exhibit remarkable metabolic diversity including methanogenesis converting hydrogen and carbon dioxide or acetate into methane via unique cofactors like methanofuran, tetrahydromethanopterin, and coenzyme M, anaerobic respiration using sulfur, nitrate, or ferric iron as electron acceptors, and oxidative phosphorylation driven by archaeal A-type ATP synthase related to vacuolar ATPases. Some halophiles like Halobacterium salinarum perform light-driven proton pumping via bacteriorhodopsin, a retinal-based phototrophy fundamentally different from chlorophyll-based photosynthesis. Chlorophyll-based oxygenic photosynthesis requiring photosystems I and II, chlorophyll a, and Calvin cycle enzymes for carbon fixation is characteristic of cyanobacteria and eukaryotic algae and plants, not of archaeal domain. No archaeon synthesizes chlorophyll or assembles photosystem reaction centers containing chlorophyll. Archaeal phototrophy relies on simple rhodopsins, not chlorin pigments. Hence absence of chlorophyll-based photosynthesis is defining metabolic gap, while methanogenesis remains unique archaeal contribution to global carbon cycle and greenhouse gas production in anaerobic environments such as wetlands and rumen. Photosynthetic bacteria use chlorophyll to harvest light, generating reducing power and ATP via electron transport chains, while archaeal bacteriorhodopsin pumps protons using retinal isomerization without producing reducing equivalents, representing functional convergence but chemically distinct phototrophy that does not fix carbon via Calvin cycle and therefore not counted as true chlorophyll photosynthesis.
Ref: Madigan et al., Brock Biology, Methanogenesis and Phototrophy; Thauer et al., Nature Rev Microbiol 2008, Methanogenic Pathways.
Leptin is secreted by adipose tissue and plays a key role in regulating appetite and body weight.
Ref: NCERT Class 11 Biology Chapter 19: Chemical Coordination and Integration Endocrine Disorders
