What molecule determines whether pyruvic acid will undergo fermentation or be sent to the Krebs cycle?<\/p>\n\n\n\n
The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n The molecule that determines whether pyruvic acid will undergo fermentation or be sent to the Krebs cycle is oxygen (O\u2082)<\/strong>.<\/p>\n\n\n\n Cellular respiration is a metabolic process that cells use to produce energy in the form of ATP. The fate of pyruvic acid (pyruvate)<\/strong> depends on the availability of oxygen<\/strong> in the cell.<\/p>\n\n\n\n In the presence of sufficient oxygen (aerobic conditions<\/strong>), pyruvic acid is transported into the mitochondria, where it is converted into acetyl-CoA<\/strong> by the enzyme pyruvate dehydrogenase. Acetyl-CoA then enters the Krebs cycle (citric acid cycle)<\/strong>, where it undergoes a series of reactions that generate NADH and FADH\u2082. These electron carriers then donate electrons to the electron transport chain (ETC)<\/strong>, leading to the production of large amounts of ATP through oxidative phosphorylation<\/strong>. This process is highly efficient and produces up to 38 ATP molecules per glucose molecule.<\/p>\n\n\n\n However, under anaerobic conditions<\/strong> (when oxygen is scarce or absent), the electron transport chain cannot function efficiently because oxygen is the final electron acceptor. This causes a backup in the system, preventing NADH from being oxidized back to NAD\u207a. Since glycolysis requires NAD\u207a to continue, cells use an alternative pathway\u2014fermentation<\/strong>\u2014to regenerate NAD\u207a. In lactic acid fermentation<\/strong>, pyruvate is converted into lactic acid<\/strong> (in animal cells), while in alcoholic fermentation<\/strong>, pyruvate is converted into ethanol and CO\u2082 (in yeast and some bacteria). Fermentation allows glycolysis to continue producing ATP, but it is much less efficient, yielding only 2 ATP molecules per glucose molecule.<\/p>\n\n\n\n Thus, the availability of oxygen<\/strong> is the key factor that determines whether pyruvic acid proceeds to the Krebs cycle<\/strong> (aerobic respiration) or undergoes fermentation<\/strong> (anaerobic respiration). Cells adapt their metabolic pathways based on oxygen availability to maintain energy production efficiently.<\/p>\n","protected":false},"excerpt":{"rendered":" What molecule determines whether pyruvic acid will undergo fermentation or be sent to the Krebs cycle? The correct answer and explanation is : The molecule that determines whether pyruvic acid will undergo fermentation or be sent to the Krebs cycle is oxygen (O\u2082). Explanation (300 words) Cellular respiration is a metabolic process that cells use […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-204386","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/204386","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=204386"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/204386\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=204386"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=204386"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=204386"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Explanation (300 words)<\/h3>\n\n\n\n