Oxygen crosses a plasma membrane
a. through facilitated diffusion.
b. by osmosis.
c. with the help of a nonspecific transporter.
d. through simple diffusion.
e. through porins.<\/p>\n\n\n\n
The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n Correct Answer: d. through simple diffusion.<\/strong><\/p>\n\n\n\n Oxygen (O\u2082) crosses a plasma membrane through simple diffusion<\/strong>, which is a passive transport process. Simple diffusion does not require energy (ATP) and occurs when molecules move from an area of high concentration to an area of low concentration<\/strong> directly through the lipid bilayer of the cell membrane.<\/p>\n\n\n\n The plasma membrane<\/strong> is made up of a phospholipid bilayer<\/strong>, with hydrophilic (water-attracting) heads facing outward and hydrophobic (water-repelling) tails facing inward. This structure creates a selective barrier<\/strong> that allows certain small, nonpolar molecules to pass through easily, while blocking larger or polar substances.<\/p>\n\n\n\n Oxygen is a small, nonpolar gas molecule<\/strong>, which means it is lipid-soluble<\/strong> and can diffuse freely across the hydrophobic core<\/strong> of the membrane without the need for transport proteins or channels. This is in contrast to ions or polar molecules like glucose or water, which usually require protein channels or carriers.<\/p>\n\n\n\n Once oxygen diffuses into the cell, it is used by mitochondria during aerobic respiration<\/strong> to produce energy in the form of ATP<\/strong>. Because cells are constantly using oxygen, the concentration of oxygen inside the cell is typically lower than outside<\/strong>, maintaining a gradient that promotes continuous diffusion.<\/p>\n\n\n\n Let\u2019s briefly clarify the incorrect choices:<\/p>\n\n\n\n Thus, oxygen\u2019s movement across the membrane is best described as simple diffusion<\/strong>, driven purely by its concentration gradient and its ability to dissolve in the lipid membrane.<\/p>\n","protected":false},"excerpt":{"rendered":" Oxygen crosses a plasma membranea. through facilitated diffusion.b. by osmosis.c. with the help of a nonspecific transporter.d. through simple diffusion.e. through porins. The Correct Answer and Explanation is: Correct Answer: d. through simple diffusion. Explanation (300 words): Oxygen (O\u2082) crosses a plasma membrane through simple diffusion, which is a passive transport process. Simple diffusion does […]<\/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-213450","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/213450","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=213450"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/213450\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=213450"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=213450"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=213450"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Explanation (300 words):<\/strong><\/h3>\n\n\n\n
\n