Instant Access to A Level Biology Revision

Sign up now to get access to the entire library of A Level Biology resources for all exam boards

img.wp-smiley,img.emoji{display:inline !important;border:none !important;box-shadow:none !important;height:1em !important;width:1em !important;margin:0 .07em !important;vertical-align:-.1em !important;background:none !important;padding:0 !important;}.has-text-align-justify{text-align:justify;}.safe-svg-cover{text-align:center;}.safe-svg-cover .safe-svg-inside{display:inline-block;max-width:100%;}.safe-svg-cover svg{height:100%;max-height:100%;max-width:100%;width:100%;}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-25{width:calc(25% - .5rem);}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-25 .wp-block-button__link{width:100%;}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-50{width:calc(50% - .5rem);}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-50 .wp-block-button__link{width:100%;}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-75{width:calc(75% - .5rem);}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-75 .wp-block-button__link{width:100%;}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-100{margin-right:0;width:100%;}.wp-block-restrict-content-pro-content-upgrade-redirect .wp-block-button__width-100 .wp-block-button__link{width:100%;}.wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em;}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none;}body .is-layout-flow > .alignleft{float:left;margin-inline-start:0;margin-inline-end:2em;}body .is-layout-flow > .alignright{float:right;margin-inline-start:2em;margin-inline-end:0;}body .is-layout-flow > .aligncenter{margin-left:auto !important;margin-right:auto !important;}body .is-layout-constrained > .alignleft{float:left;margin-inline-start:0;margin-inline-end:2em;}body .is-layout-constrained > .alignright{float:right;margin-inline-start:2em;margin-inline-end:0;}body .is-layout-constrained > .aligncenter{margin-left:auto !important;margin-right:auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width:var(--wp--style--global--content-size);margin-left:auto !important;margin-right:auto !important;}body .is-layout-constrained > .alignwide{max-width:var(--wp--style--global--wide-size);}body .is-layout-flex{display:flex;}body .is-layout-flex{flex-wrap:wrap;align-items:center;}body .is-layout-flex > *{margin:0;}body .is-layout-grid{display:grid;}body .is-layout-grid > *{margin:0;}.has-black-color{color:var(--wp--preset--color--black) !important;}.has-cyan-bluish-gray-color{color:var(--wp--preset--color--cyan-bluish-gray) !important;}.has-white-color{color:var(--wp--preset--color--white) !important;}.has-pale-pink-color{color:var(--wp--preset--color--pale-pink) !important;}.has-vivid-red-color{color:var(--wp--preset--color--vivid-red) !important;}.has-luminous-vivid-orange-color{color:var(--wp--preset--color--luminous-vivid-orange) !important;}.has-luminous-vivid-amber-color{color:var(--wp--preset--color--luminous-vivid-amber) !important;}.has-light-green-cyan-color{color:var(--wp--preset--color--light-green-cyan) !important;}.has-vivid-green-cyan-color{color:var(--wp--preset--color--vivid-green-cyan) !important;}.has-pale-cyan-blue-color{color:var(--wp--preset--color--pale-cyan-blue) !important;}.has-vivid-cyan-blue-color{color:var(--wp--preset--color--vivid-cyan-blue) !important;}.has-vivid-purple-color{color:var(--wp--preset--color--vivid-purple) !important;}.has-black-background-color{background-color:var(--wp--preset--color--black) !important;}.has-cyan-bluish-gray-background-color{background-color:var(--wp--preset--color--cyan-bluish-gray) !important;}.has-white-background-color{background-color:var(--wp--preset--color--white) !important;}.has-pale-pink-background-color{background-color:var(--wp--preset--color--pale-pink) !important;}.has-vivid-red-background-color{background-color:var(--wp--preset--color--vivid-red) !important;}.has-luminous-vivid-orange-background-color{background-color:var(--wp--preset--color--luminous-vivid-orange) !important;}.has-luminous-vivid-amber-background-color{background-color:var(--wp--preset--color--luminous-vivid-amber) !important;}.has-light-green-cyan-background-color{background-color:var(--wp--preset--color--light-green-cyan) !important;}.has-vivid-green-cyan-background-color{background-color:var(--wp--preset--color--vivid-green-cyan) !important;}.has-pale-cyan-blue-background-color{background-color:var(--wp--preset--color--pale-cyan-blue) !important;}.has-vivid-cyan-blue-background-color{background-color:var(--wp--preset--color--vivid-cyan-blue) !important;}.has-vivid-purple-background-color{background-color:var(--wp--preset--color--vivid-purple) !important;}.has-black-border-color{border-color:var(--wp--preset--color--black) !important;}.has-cyan-bluish-gray-border-color{border-color:var(--wp--preset--color--cyan-bluish-gray) !important;}.has-white-border-color{border-color:var(--wp--preset--color--white) !important;}.has-pale-pink-border-color{border-color:var(--wp--preset--color--pale-pink) !important;}.has-vivid-red-border-color{border-color:var(--wp--preset--color--vivid-red) !important;}.has-luminous-vivid-orange-border-color{border-color:var(--wp--preset--color--luminous-vivid-orange) !important;}.has-luminous-vivid-amber-border-color{border-color:var(--wp--preset--color--luminous-vivid-amber) !important;}.has-light-green-cyan-border-color{border-color:var(--wp--preset--color--light-green-cyan) !important;}.has-vivid-green-cyan-border-color{border-color:var(--wp--preset--color--vivid-green-cyan) !important;}.has-pale-cyan-blue-border-color{border-color:var(--wp--preset--color--pale-cyan-blue) !important;}.has-vivid-cyan-blue-border-color{border-color:var(--wp--preset--color--vivid-cyan-blue) !important;}.has-vivid-purple-border-color{border-color:var(--wp--preset--color--vivid-purple) !important;}.has-vivid-cyan-blue-to-vivid-purple-gradient-background{background:var(--wp--preset--gradient--vivid-cyan-blue-to-vivid-purple) !important;}.has-light-green-cyan-to-vivid-green-cyan-gradient-background{background:var(--wp--preset--gradient--light-green-cyan-to-vivid-green-cyan) !important;}.has-luminous-vivid-amber-to-luminous-vivid-orange-gradient-background{background:var(--wp--preset--gradient--luminous-vivid-amber-to-luminous-vivid-orange) !important;}.has-luminous-vivid-orange-to-vivid-red-gradient-background{background:var(--wp--preset--gradient--luminous-vivid-orange-to-vivid-red) !important;}.has-very-light-gray-to-cyan-bluish-gray-gradient-background{background:var(--wp--preset--gradient--very-light-gray-to-cyan-bluish-gray) !important;}.has-cool-to-warm-spectrum-gradient-background{background:var(--wp--preset--gradient--cool-to-warm-spectrum) !important;}.has-blush-light-purple-gradient-background{background:var(--wp--preset--gradient--blush-light-purple) !important;}.has-blush-bordeaux-gradient-background{background:var(--wp--preset--gradient--blush-bordeaux) !important;}.has-luminous-dusk-gradient-background{background:var(--wp--preset--gradient--luminous-dusk) !important;}.has-pale-ocean-gradient-background{background:var(--wp--preset--gradient--pale-ocean) !important;}.has-electric-grass-gradient-background{background:var(--wp--preset--gradient--electric-grass) !important;}.has-midnight-gradient-background{background:var(--wp--preset--gradient--midnight) !important;}.has-small-font-size{font-size:var(--wp--preset--font-size--small) !important;}.has-medium-font-size{font-size:var(--wp--preset--font-size--medium) !important;}.has-large-font-size{font-size:var(--wp--preset--font-size--large) !important;}.has-x-large-font-size{font-size:var(--wp--preset--font-size--x-large) !important;}.wp-block-navigation a:where(:not(.wp-element-button)){color:inherit;}.wp-block-pullquote{font-size:1.5em;line-height:1.6;}a:hover,a:focus,a:active{color:#000;}.wp-block-group__inner-container{max-width:1100px;margin-left:auto;margin-right:auto;}select,textarea{font-family:"Nunito",sans-serif;font-size:18px;}.entry-content > [class*="wp-block-"]:not(:last-child){margin-bottom:1.5em;}.sidebar .widget{font-size:17px;}h4{font-size:inherit;}h5{font-size:inherit;}.top-bar{background-color:#636363;color:#fff;}.top-bar a{color:#fff;}.top-bar a:hover{color:#303030;}.main-title a:hover{color:#fff;}.site-description{color:#757575;}.main-navigation .menu-bar-items{color:#fff;}.main-navigation .main-nav ul li:hover > a,.main-navigation .main-nav ul li:focus > a,.main-navigation .main-nav ul li.sfHover > a,.main-navigation .menu-bar-item:hover > a,.main-navigation .menu-bar-item.sfHover > a{color:#fff;background-color:#3d444b;}button.menu-toggle:hover,button.menu-toggle:focus,.main-navigation .mobile-bar-items a,.main-navigation .mobile-bar-items a:hover,.main-navigation .mobile-bar-items a:focus{color:#fff;}.main-navigation .main-nav ul li[class*="current-menu-"] > a{color:#fff;}.main-navigation .main-nav ul li[class*="current-menu-"] > a:hover,.main-navigation .main-nav ul li[class*="current-menu-"].sfHover > a{color:#fff;}.navigation-search input[type="search"],.navigation-search input[type="search"]:active,.navigation-search input[type="search"]:focus,.main-navigation .main-nav ul li.search-item.active > a,.main-navigation .menu-bar-items .search-item.active > a{color:#fff;background-color:#3d444b;}.main-navigation .main-nav ul ul li:hover > a,.main-navigation .main-nav ul ul li:focus > a,.main-navigation .main-nav ul ul li.sfHover > a{color:#fff;background-color:#2c3338;}.main-navigation .main-nav ul ul li[class*="current-menu-"] > a{color:#fff;background-color:#3d444b;}.main-navigation .main-nav ul ul li[class*="current-menu-"] > a:hover,.main-navigation .main-nav ul ul li[class*="current-menu-"].sfHover > a{color:#fff;background-color:#3d444b;}.separate-containers .comments-area,.separate-containers .page-header,.one-container .container,.separate-containers .paging-navigation,.inside-page-header{background-color:#fff;}.entry-meta{color:#595959;}.entry-meta a{color:#595959;}.entry-meta a:hover{color:#1e73be;}.sidebar .widget{background-color:#fff;}.sidebar .widget .widget-title{color:#000;}.footer-widgets .widget-title{color:#d63638;}.site-info a{color:#fff;}.site-info a:hover{color:#606060;}.footer-bar .widget_nav_menu .current-menu-item a{color:#606060;}input[type="email"],input[type="url"],input[type="search"],input[type="tel"],input[type="number"],textarea,select{color:#666;background-color:#fafafa;border-color:#ccc;}input[type="text"]:focus,input[type="email"]:focus,input[type="url"]:focus,input[type="password"]:focus,input[type="search"]:focus,input[type="tel"]:focus,input[type="number"]:focus,textarea:focus,select:focus{color:#666;background-color:#fff;border-color:#bfbfbf;}html input[type="button"],input[type="reset"],a.button,a.wp-block-button__link:not(.has-background){color:#ebf7f1;background-color:#00a32a;}button:hover,html input[type="button"]:hover,input[type="reset"]:hover,input[type="submit"]:hover,a.button:hover,button:focus,html input[type="button"]:focus,input[type="reset"]:focus,input[type="submit"]:focus,a.button:focus,a.wp-block-button__link:not(.has-background):active,a.wp-block-button__link:not(.has-background):focus,a.wp-block-button__link:not(.has-background):hover{color:#fff;background-color:#008a20;}a.generate-back-to-top{background-color:rgba(0,0,0,.4);color:#fff;}a.generate-back-to-top:hover,a.generate-back-to-top:focus{background-color:rgba(0,0,0,.6);color:#fff;}.inside-top-bar{padding:10px;}.entry-content .alignwide,body:not(.no-sidebar) .entry-content .alignfull{margin-left:-40px;width:calc(100% + 80px);max-width:calc(100% + 80px);}.rtl .menu-item-has-children .dropdown-menu-toggle{padding-left:20px;}.rtl .main-navigation .main-nav ul li.menu-item-has-children > a{padding-right:20px;}.one-container .sidebar .widget{padding:0px;}.dynamic-author-image-rounded{border-radius:100%;}.dynamic-featured-image,.dynamic-author-image{vertical-align:middle;}.one-container.blog .dynamic-content-template:not(:last-child),.one-container.archive .dynamic-content-template:not(:last-child){padding-bottom:0px;}.dynamic-entry-excerpt > p:last-child{margin-bottom:0px;}img#wpstats{display:none;}