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class="fa fa-fw"></i><a href="../607/membrane-structure-13-.html">Membrane structure 1.3 </a></label></li><li class=""><label style="padding-left: 0px"><i class="fa fa-fw"></i><a href="../575/membrane-transport-14-.html">Membrane transport 1.4 </a></label></li><li class=""><label style="padding-left: 0px"><i class="fa fa-fw"></i><a href="../608/the-origin-of-cells-15.html">The origin of cells 1.5</a></label></li><li class=""><label style="padding-left: 0px"><i class="fa fa-fw"></i><a href="../609/cell-division-16.html">Cell division 1.6</a></label></li></ul></div> <div class="hidden-xs hidden-sm"> <button class="btn btn-default btn-block text-xs-center" data-toggle="modal" data-target="#modal-feedback" style="margin-bottom: 10px"><i class="fa fa-send"></i> Feedback</button> </div> </div> <div class="col-md-9" id="main-column"> <h1 class="page_title"> Introduction to cells 1.1 <a href="#" class="mark-page-favorite pull-right" data-pid="486" title="Mark as favorite" onclick="return false;"><i class="fa fa-star-o"></i></a> </h1> <ol class="breadcrumb"> <li><a href="../../../biology.html"><i class="fa fa-home"></i></a><i class="fa fa-fw fa-chevron-right divider"></i></li><li><a href="../462/01-cell-biology.html">01 Cell biology</a><i class="fa fa-fw fa-chevron-right divider"></i></li><li><span class="gray">Introduction to cells 1.1</span></li> <span class="pull-right" style="color: #555" title="Suggested study time: 30 minutes"><i class="fa fa-clock-o"></i> 30'</span> </ol> <article id="main-article"> <style type="text/css">ol.breadcrumb { margin-bottom: 0 }</style><div id="toc-1675505946" class="toc"><a href="#" class="toc-switcher" title="Show table of contents"><small><i class="fa fa-reorder"></i> Table of contents <span class="pull-right"><i class="fa fa-chevron-down"></i></span></small></a><ol><li><a href="#header-1" class="scroll-to" data-target="header-1">Essentials - quick revision through the whole topic</a></li><li><a href="#header-2" class="scroll-to" data-target="header-2">Summary list for 1.1 Introduction to cells</a></li><li><a href="#header-3" class="scroll-to" data-target="header-3">Mindmaps</a></li><li><a href="#header-4" class="scroll-to" data-target="header-4">Skills video tutorial on calculating size</a></li><li><a href="#header-5" class="scroll-to" data-target="header-5">Model answer</a></li><li><a href="#header-6" class="scroll-to" data-target="header-6">Model answer</a></li><li><a href="#header-7" class="scroll-to" data-target="header-7">Model answer</a></li><li><a href="#header-8" class="scroll-to" data-target="header-8">Model answer</a></li><li><a href="#header-9" class="scroll-to" data-target="header-9">Multiple Choice questions</a><ol></ol></li><li><a href="#header-10" class="scroll-to" data-target="header-10"> 1.1 Intro to cells quiz 1/1 </a></li><li><a href="#header-11" class="scroll-to" data-target="header-11"> 1.1 Intro to cells (2) 1/1 </a></li></ol><li><a href="#header-12" class="scroll-to" data-target="header-12">Drag and drop activities</a></li></div><div class="intro-card" readonly="false"><img class="intro-image" readonly="true" src="../../images/01_cells/acetabularia-1.png" style="width: 614px; height: 670px;"> <div class="content" readonly="true"> <div class="text">Cell theory states that all organisms are made of cells. This is true in most cases but there are some notable exceptions, like skeletal muscle. This topic covers the cell theory, the exceptions to cell theory and how cells differentiate during cell growth. Using microscopes is part of the topic, as is measuring the size of cells.</div> </div> </div> <div class="panel panel-turquoise"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Key concepts</p> </div> </div> <div class="panel-body"> <div> <p>Learn the biological vocabulary for 1.1 Introduction to cells and test yourself using these flash cards.</p> <p><iframe frameborder="0" height="420" scrolling="no" src="https://quizlet.com/51538144/flashcards/embed" width="100%"><br> </iframe></p> </div> </div> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <div class="panel panel-default"> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <div class="panel panel-yellow"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Essentials</p> </div> </div> <div class="panel-body"> <div> <h3 id="header-1">Essentials - quick revision through the whole topic<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p>These slides summarise the essential understanding and skills in this topic. <br> They contain short explanations in text and images - good revision for all students.</p> <p>Read the slides and look up any words or details you find difficult to understand.</p> <div id="carousel-67" class="dynamic-gallery carousel slide" data-id="67"><div class="carousel-inner" role="listbox"><div class="item active"><a class="fancy" href="../../../std-galleries/5-67/11cells-intro.jpg" data-fancybox="gallery-67" title="" data-caption=""><img alt="" src="../../../std-galleries/5-67/11cells-intro.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-67/11cells-intro2.jpg" data-fancybox="gallery-67" title="" data-caption=""><img alt="" src="../../../std-galleries/5-67/11cells-intro2.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-67/11cells-intro3.jpg" data-fancybox="gallery-67" title="" data-caption=""><img alt="" src="../../../std-galleries/5-67/11cells-intro3.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-67/11cells-intro4.jpg" data-fancybox="gallery-67" title="" data-caption=""><img alt="" src="../../../std-galleries/5-67/11cells-intro4.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-67/11cells-intro5.jpg" data-fancybox="gallery-67" title="" data-caption=""><img alt="" src="../../../std-galleries/5-67/11cells-intro5.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-67/11cells-intro6.jpg" data-fancybox="gallery-67" title="" data-caption=""><img alt="" src="../../../std-galleries/5-67/11cells-intro6.jpg"></a></div></div><a class="left carousel-control" href="#carousel-67" role="button" data-slide="prev"><i class="fa fa-fw fa-chevron-left"></i></a><a class="right carousel-control" href="#carousel-67" role="button" data-slide="next"><i class="fa fa-fw fa-chevron-right"></i></a></div><ol class="std-carousel-indicators"><li data-index="0"><img title="Click to view" src="../../../std-galleries/5-67/11cells-intro-thumb128.jpg"><li><li data-index="1"><img title="Click to view" src="../../../std-galleries/5-67/11cells-intro2-thumb128.jpg"><li><li data-index="2"><img title="Click to view" src="../../../std-galleries/5-67/11cells-intro3-thumb128.jpg"><li><li data-index="3"><img title="Click to view" src="../../../std-galleries/5-67/11cells-intro4-thumb128.jpg"><li><li data-index="4"><img title="Click to view" src="../../../std-galleries/5-67/11cells-intro5-thumb128.jpg"><li><li data-index="5"><img title="Click to view" src="../../../std-galleries/5-67/11cells-intro6-thumb128.jpg"><li></li></ol> </div> </div> <div class="panel-footer"> <div> <p>These slides summarise the essential understanding and skills in this topic. <br> They contain short explanations in text and images - great revision.</p> <p>Read the slides and look up any words or details you find difficult to understand.</p> <div id="carousel-210" class="dynamic-gallery carousel slide" data-id="210"><div class="carousel-inner" role="listbox"><div class="item active"><a class="fancy" href="../../../std-galleries/5-210/112movement-1.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-1.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-2.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-2.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-3.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-3.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-4.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-4.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-5.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-5.jpg"></a></div></div><a class="left carousel-control" href="#carousel-210" role="button" data-slide="prev"><i class="fa fa-fw fa-chevron-left"></i></a><a class="right carousel-control" href="#carousel-210" role="button" data-slide="next"><i class="fa fa-fw fa-chevron-right"></i></a></div><ol class="std-carousel-indicators"><li data-index="0"><img title="Click to view" src="../../../std-galleries/5-210/112movement-1-thumb128.jpg"><li><li data-index="1"><img title="Click to view" src="../../../std-galleries/5-210/112movement-2-thumb128.jpg"><li><li data-index="2"><img title="Click to view" src="../../../std-galleries/5-210/112movement-3-thumb128.jpg"><li><li data-index="3"><img title="Click to view" src="../../../std-galleries/5-210/112movement-4-thumb128.jpg"><li><li data-index="4"><img title="Click to view" src="../../../std-galleries/5-210/112movement-5-thumb128.jpg"><li></li></ol> </div> </div> </div> <div class="panel panel-violet"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Summary</p> </div> </div> <div class="panel-body"> <div> <h3 id="header-2">Summary list for 1.1 Introduction to cells<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p><u>Cell theory</u></p> <ul> <li>According to cell theory, living organisms are composed of cells.</li> <li>Organisms consisting of only one cell carry out all functions of life in that cell, e.g. <em>Paramecium, Chlorella</em>.</li> <li>Identifying the characteristics of living things (Mr H. Gren - <strong>m</strong>etabolism,<strong> r</strong>esponse, <strong>h</strong>omeostasis, <strong>g</strong>rowth, <strong>r</strong>eproduction, <strong>e</strong>xcretion & <strong>n</strong>utrition).</li> <li>Surface area to volume ratio is important in the limitation of cell size.</li> <li>Multicellular organisms have properties that emerge from the interaction of their cellular components, (Emergent properties).</li> <li>Specialised tissues can develop by cell differentiation in multicellular organisms.</li> <li>Differentiation involves the expression of some genes and not others in a cell.</li> <li>Stem cells can divide and differentiate along different pathways in embryonic development which makes stem cells useful for therapeutic uses (e.g. Stargardt's disease).</li> <li>There are ethical concerns about the use of embryo stem cells.</li> </ul> <p><u>Calculating magnification and size</u></p> <ul> <li>Calculate the magnification of an electron microscope image from a scale bar.</li> <li>Calculate specimen size using a scale bar.</li> <li>Calculate specimen size using magnification.</li> </ul> <hr class="hidden-separator"> <h3 id="header-3">Mindmaps<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p>These diagrams summarise the main sections of topic 1.1.<br> Test if you can draw something like these concept maps from memory.<br> Can you ask several questions about the points using command terms, e.g List, Describe, Outline, Explain,</p> <div id="carousel-70" class="dynamic-gallery carousel slide" data-id="70"><div class="carousel-inner" role="listbox"><div class="item active"><a class="fancy" href="../../../std-galleries/5-70/11cellsintrommlist.jpg" data-fancybox="gallery-70" title="" data-caption=""><img alt="" src="../../../std-galleries/5-70/11cellsintrommlist.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-70/11cellsintrommsimple.jpg" data-fancybox="gallery-70" title="" data-caption=""><img alt="" src="../../../std-galleries/5-70/11cellsintrommsimple.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-70/11cellsintrommfull.jpg" data-fancybox="gallery-70" title="" data-caption=""><img alt="" src="../../../std-galleries/5-70/11cellsintrommfull.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-70/introduction-to-cells-1-1small2.jpg" data-fancybox="gallery-70" title="" data-caption=""><img alt="" src="../../../std-galleries/5-70/introduction-to-cells-1-1small2.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-70/notesspiderdiagsmall.jpeg" data-fancybox="gallery-70" title="" data-caption=""><img alt="" src="../../../std-galleries/5-70/notesspiderdiagsmall.jpeg"></a></div></div><a class="left carousel-control" href="#carousel-70" role="button" data-slide="prev"><i class="fa fa-fw fa-chevron-left"></i></a><a class="right carousel-control" href="#carousel-70" role="button" data-slide="next"><i class="fa fa-fw fa-chevron-right"></i></a></div><ol class="std-carousel-indicators"><li data-index="0"><img title="Click to view" src="../../../std-galleries/5-70/11cellsintrommlist-thumb128.jpg"><li><li data-index="1"><img title="Click to view" src="../../../std-galleries/5-70/11cellsintrommsimple-thumb128.jpg"><li><li data-index="2"><img title="Click to view" src="../../../std-galleries/5-70/11cellsintrommfull-thumb128.jpg"><li><li data-index="3"><img title="Click to view" src="../../../std-galleries/5-70/introduction-to-cells-1-1small2-thumb128.jpg"><li><li data-index="4"><img title="Click to view" src="../../../std-galleries/5-70/notesspiderdiagsmall-thumb128.jpg"><li></li></ol> </div> </div> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <div class="panel panel-default"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Exam style questions</p> </div> </div> <div class="panel-body"> <div> <h3 id="header-4">Skills video tutorial on calculating size<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p>How to calculate the size of a cell using the scale bar.</p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/280054220?portrait=0"></iframe></div> <script src="../../../api/player.js"></script> <p><a href="https://vimeo.com/280054220">Calculating cell size using a scale bar</a> from <a href="https://vimeo.com/user14306679">David Faure</a> on <a href="https://vimeo.com">Vimeo</a>.</p> </div> <div class="panel panel-has-colored-body panel-has-border panel-default"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p><a id="p2q" name="p2q"></a>Exam question on multicellular organisms</p> </div> </div> <div class="panel-body"> <div> <p>This is a tricky structured question which brings together several aspects of the topic 1.1</p> <div class="yellowBg"> <p><strong>Explain the origins of multicellular organisms and its biological significance. [5]</strong></p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> </div> <p>Try to write an answer first then compare your answer with the model answer shown below, and explained in the video.</p> <div class="video-embed vimeo"><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" height="420" width="100%" src="https://player.vimeo.com/video/380999031"></iframe></div> <p>[Many thanks to Catarina Gouveia, St. Dominic's International School, Portugal, for this question and mark scheme]</p> <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-5">Model answer<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p><strong>Explain the origins of multicellular organisms and its biological significance. [8]</strong></p> <p><span style="color:#FF0000;">Multicellular organisms are organisms made from many cells.</span></p> <p><span style="color:#FF0000;">Multicellular organisms originated from a unicellular organism.</span></p> <p><span style="color:#FF0000;">Cells started to divide because growing bigger was not an advantage / it is limited by low SA:VOL ratio.</span></p> <p><span style="color:#FF0000;">The evolution of multicellular organisms allowed specialization of cells and tissues.</span></p> <p><span style="color:#FF0000;">Specialized tissues can develop by cell differentiation in multicellular organisms.</span></p> <p><span style="color:#FF0000;">Differentiation involves the expression of some genes in a cell’s genome and not others.</span></p> <p><span style="color:#FF0000;">Multicellular organisms can be bigger than unicellular organisms.</span></p> <p><span style="color:#FF0000;">Large size can allow the organism to reduce their metabolic rate. </span></p> <p><span style="color:#FF0000;">Large organisms can be more independent with regards to the environment / they can modify their enviroment</span>.</p> <p style="margin-left:36.0pt;text-indent:-18.0pt;line-height:150%"><o:p></o:p></p> </div> </section> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="panel panel-has-colored-body panel-expandable panel-has-border panel-default"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Extra exam question on cell function - - - click the + symbol to open it -- ></p> </div> </div> <div class="panel-body"> <div> <p>This question requires knowledge of the functioning of single celled and multicellular organisms.</p> <p>Write your answer and then compare it with the model answer</p> <div class="yellowBg"> <p><strong>Distinguish between single celled condition and the multicellular condition. (4 marks).</strong></p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> </div> <p>Write your answer and then click on the "+" icon for a model answer.</p> <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-6">Model answer<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p><strong>Distinguish between single celled condition and the multicellular condition. (4 marks).</strong></p> <p> <em>Distinguish between means give an account of the differences putting both comparators in each sentence.</em></p> <ul> <li><span style="color:#FF0000;">Single celled organisms consist of one cell that carries out all the functions of the organism; multicellular organisms consist of many types of cells, each with specific functions.</span></li> <li><span style="color:#FF0000;">In single celled organisms each cell reproduces by binary fission; multicellular organisms have specialised cells which reproduce by mitosis.</span></li> <li><span style="color:#FF0000;">The daughter cells produced by binary fission are identical to the parent cell whereas in multicellular organisms the cells produced by mitosis can differentiate into various kinds of mature cells in the process of growth.</span></li> <li><span style="color:#FF0000;">Multicellular organisms have specialised cells organised into tissues and organs with specific functions.</span></li> <li><span style="color:#FF0000;">Multicellular organisms can regenerate and repair damaged tissues.</span></li> </ul> </div> </section> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="panel panel-has-colored-body panel-expandable panel-has-border panel-default"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Extra exam question on specialised cells - - - click the + symbol to open it -- ></p> </div> </div> <div class="panel-body"> <div> <p><span calibri="" style="font-size:11.0pt;line-height:107%; font-family:">Exam style question on cell differentiation.</span></p> <p>This question requires knowledge of the mechanism of cell differentiation.</p> <p>Write your answer to the question and then compare your answer with the model answer.</p> <div class="yellowBg"> <p><b><span calibri="" style="font-size:11.0pt;line-height:107%; font-family:">Explain how stem cells replicate to produce mature, specialised cells (4 marks)</span></b></p> <p><em>Command term hints: Explain means that you must include details of reasons and causes.</em></p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> </div> Write your answer then click on the "+" icon to see a model answer <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-7">Model answer<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p><b><span calibri="" style="font-size:11.0pt;line-height:107%; font-family:">Explain how stem cells replicate to produce mature, specialised cells (4 marks)</span></b></p> <ul> <li><span style="color:#FF0000;">Stem cells can divide rapidly by mitosis.</span></li> <li><span style="color:#FF0000;">When the two daughter cells are formed, one differentiates into a mature cell such as a red blood cell.</span></li> <li><span style="color:#FF0000;">the other cell remains as a stem cell to divide again by mitosis.</span></li> <li><span style="color:#FF0000;">When the cell differentiates into a mature cell, particular genes are expressed.</span></li> <li><span style="color:#FF0000;">To produce proteins that allow the cell to mature into a specialised cell.</span></li> <li><span style="color:#FF0000;">Example - the developing red blood cell produces haemoglobin (other valid example)</span>.</li> </ul> </div> </section> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="panel panel-has-colored-body panel-expandable panel-has-border panel-default"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Extra exam question on calculating magnification - - - click the + to open it -- ></p> </div> </div> <div class="panel-body"> <div> <p>You previously looked at a video on cell size. Now see if you can do a true size calculation.</p> <p>This question requires knowledge of converting to true size using magnification.</p> <div class="yellowBg"> <p><strong>The size of a mitochondrion on an electron micrograph is 43 mm. </strong></p> <p><strong><img alt="" src="../../images/01_cells/mitochondrion.png" style="width: 250px; height: 187px;"><br> If the magnification of the micrograph is x20000 calculate the true size of the mitochondrion. (2 marks).</strong></p> <p><em>Show your calculation, you may gain marks for the method of the calculation even if your answer is incorrect.</em></p> <p>........................................................................ ..................................................................</p> <p>........................................................................ ..................................................................</p> </div> Click on the "+" icon to see a model answer of the calculation. <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-8">Model answer<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p><strong>The size of a mitochondrion on an electron micrograph is 43 mm.<br> If the magnification of the micrograph is x20000 calculate the true size of the mitochondrion. (2 marks).</strong></p> <p>One method divides by the magnification first.</p> <ul> <li>measured size divided by the magnification</li> <li><span style="color:#FF0000;">43mm/20000 = 0.00215mm.</span></li> <li><span style="color:#FF0000;"></span>converted to µm<span style="color:#FF0000;"></span></li> <li><span style="color:#FF0000;">0.00215mm x 1000 = 2.15μm.</span></li> </ul> <p>Another option is to convert the mm measurement into µm first. This avoids so many decimals.</p> <ul> <li>measured size converted to µm</li> <li><span style="color:#FF0000;">43mm x 1000 = 43 000 µm</span></li> <li>divided by the magnification.</li> <li><span style="color:#FF0000;">43000/20000 µm = 2.15μm.</span></li> </ul> </div> </section> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> </div> </div> <div class="panel panel-green"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Test yourself</p> </div> </div> <div class="panel-body"> <div> <h3 id="header-9"><a id="mcq" name="mcq"></a>Multiple Choice questions<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p>This quiz contains a set of multiple choice questions covering the topic.<br> Explanations of each answer are displayed after you click to check the answer(s).</p> <br><a class="btn btn-primary btn-block text-center" data-toggle="modal" href="#11067311"><i class="fa fa-play"></i> START QUIZ!</a><div class="modal fade modal-slide-quiz" id="11067311"> <div class="modal-dialog" style="width: 95vw; max-width: 960px"> <div class="modal-content"> <div class="modal-header slide-quiz-title"> <h4 id="header-10"> 1.1 Intro to cells quiz <strong class="q-number pull-right"> <span class="counter">1</span>/<span class="total">1</span> </strong> <small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h4> </div> <div class="modal-body p-xs-3"> <div class="slide-quiz" data-stats="5-196-486" style="opacity: 0"> <div class="exercise shadow-bottom"><div class="q-question"><p>The 'Cell theory' explains the nature of living things.<br>Which statement best describes Cell theory?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> Cells divide by meiosis.</label></p><p><label class="radio"><input class="c" type="radio"> Cells make up all living organisms.</label></p><p><label class="radio"><input type="radio"> Cells are composed of C, H and O.</label></p><p><label class="radio"><input type="radio"> Cells can carry out photosynthesis.</label></p></div><div class="q-explanation"><p>According to cell theory, living organisms are composed of cells. <br>Cells come from pre-existing cells and cells are the smallest using of life.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Cell theory covers most, but not all cases.<br>Which one of these statements is an exception?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> The theory of spontaneous generation has been disproven.</label></p><p><label class="radio"><input type="radio"> Striated muscle cells don't have a nucleus.</label></p><p><label class="radio"><input type="radio"> Human skin is made of layers of cells which are dead.</label></p><p><label class="radio"><input class="c" type="radio"> Acetabularia algae are made from a single giant cell, not multiple small cells.</label></p></div><div class="q-explanation"><p>Exceptions to cell theory are : multinucleated striated muscle the giant single celled Acetabularia algae.<br>Also, organisms consisting of only one cell carry out all functions of life in that cell. e.g. Paramecium, Chlorella.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>There are seven processes which are said to be possessed by all living things.<br>This sweet pea plant has grown a tendril around some string, to help support its upward growth.</p><p><img alt="" src="../../images/01_cells/tendril.jpeg" style="width: 300px; height: 284px;"></p><p>Which of the characteristics of living things is illustrated in this photo?</p></div><div class="q-answer"><p><label class="radio"><input class="c" type="radio"> Response to the environment.</label></p><p><label class="radio"><input type="radio"> Homeostasis.</label></p><p><label class="radio"><input type="radio"> Excretion.</label></p><p><label class="radio"><input type="radio"> Nutrition.</label></p></div><div class="q-explanation"><p>The characteristics of living things (Mr H. Gren - metabolism, response, , homeostasis, growth, reproduction, excretion & nutrition)</p><p>The fly is responding to the closing trap, and the trap has responded to the presence of the fly.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>What is the importance of surface area to volume ratio to cells?</p></div><div class="q-answer"><p><label class="radio"><input class="c" type="radio"> It limits the size of cells</label></p><p><label class="radio"><input type="radio"> It controls the shape of cells.</label></p><p><label class="radio"><input type="radio"> It affects the respiration rate in cells.</label></p><p><label class="radio"><input type="radio"> It limits the amount of DNA in the cytoplasm.</label></p></div><div class="q-explanation"><p>Surface area to volume ratio is important in the limitation of cell size.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>When nerve cells form brain tissue they can store memories, create thoughts and coordinate movement.</p><p>If you only ever studied individual nerve cells you would never see these abilities which the brain has.</p><p>What is this type of property called?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> A peripheral property.</label></p><p><label class="radio"><input type="radio"> An integral property</label></p><p><label class="radio"><input class="c" type="radio"> An emergent property.</label></p><p><label class="radio"><input type="radio"> A powerful property.</label></p></div><div class="q-explanation"><p>Multicellular organisms have properties that emerge from the interaction of their cellular components. (Emergent properties)</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p><img alt="" src="../../images/01_cells/cell_types.jpeg" style="float: right; width: 200px; height: 225px;">The image shows a range of different cell types in the leaf of a Yucca plant.<br>How do stem cells form this range of cells? <br>What is the process called?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> Cell enlargement causes the differences, controlled by auxins.</label></p><p><label class="radio"><input type="radio"> The process is cell apoptosis, cells change because of the nucleus.</label></p><p><label class="radio"><input type="radio"> Mitosis causes stem cells to multiply and change.</label></p><p><label class="radio"><input class="c" type="radio"> The process is cell differentiation, controlled by gene expression.</label></p></div><div class="q-explanation"><p>Specialised tissues can develop by cell differentiation in multicellular organisms.</p><p>Differentiation involves the expression of some genes and not others in a cell.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Stargardt's disease is vision loss caused by the death of both cone cells and rod cells in the part of the retina around the fovea. One potential treatment for Stargardt's disease is the use of human embryonic stem cells.<br>What are the properties of these stem cells, which other cells don't have, that makes them so useful for this treatment?</p></div><div class="q-answer"><p><label class="radio"><input class="c" type="radio"> They are unspecialised and can differentiate to become any type of specialised cell.</label></p><p><label class="radio"><input type="radio"> They can make antibodies to protect against disease in the eye.</label></p><p><label class="radio"><input type="radio"> They have a large surface area to volume ratio which increases exchange of substances.</label></p><p><label class="radio"><input type="radio"> They are able to detect light which helps repair the eye.</label></p></div><div class="q-explanation"><p>Stem cells can divide and this help researchers to grow them in the lab.</p><p>They can differentiate along different pathways in embryonic development which makes stem cells useful for therapeutic uses (e.g. Stargardt's disease) because they can be grown into many different tissues.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The electron microscope image below shows a scale bar marked with 100µm.</p><p>The large 'goblet cell' in the centre is producing mucous which will protect the surface of the epithelium.</p><p><img alt="" src="../../images/01_cells/cell_mucous_glandscalebar.jpeg" style="width: 300px; height: 250px;"></p><p>What is the diameter of the goblet cell?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> 80000 µm</label></p><p><label class="radio"><input class="c" type="radio"> 80 µm</label></p><p><label class="radio"><input type="radio"> 250 µm</label></p><p><label class="radio"><input type="radio"> 20 µm</label></p></div><div class="q-explanation"><p>Calculate specimen size using a scale bar?</p><p>You can often estimate the size using the scale bar and your thumb?</p><p>More accurately, measure the scale bar length in mm, measure the diameter of the cell, in mm<br>divide cell diameter by scalebar and multiply by 100µm</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The image below shows erythrocytes and leucocytes.l.</p><p><img alt="" src="../../images/01_cells/cells_blood_scalebar2.jpeg" style="width: 300px; height: 230px;"></p><p>Using the scale bar and the ruler placed on the image, estimate the magnification of the image. <br>Which answer is the best estimate</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> x 25</label></p><p><label class="radio"><input type="radio"> x 250</label></p><p><label class="radio"><input type="radio"> x 100</label></p><p><label class="radio"><input class="c" type="radio"> x 1000</label></p></div><div class="q-explanation"><p>Calculate the magnification of an electron microscope image from a scale bar?</p><p>Convert the ruler measurement to the same units written on the scale bar, in this case 25mm is 25000µm</p><p>then divide the ruler measurement 25000 by the number on the scalebar, 25.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The blood cells below were imaged using an electron microscope.</p><p>The magnification is x3000 and the ruler measures the central cell as being 2 cm in diameter.</p><p><img alt="" src="../../images/01_cells/cells_blood_scalebar3.jpeg" style="width: 300px; height: 212px;"></p><p>Estimate the actual size of this white blood cell.</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> 6000µm</label></p><p><label class="radio"><input class="c" type="radio"> 6.6 µm</label></p><p><label class="radio"><input type="radio"> 0.6µm</label></p><p><label class="radio"><input type="radio"> 60 µm</label></p></div><div class="q-explanation"><p>Calculate specimen size using magnification?</p><p>First change the size measurement into µm units = 20000µm</p><p>Then divide by the magnification. 20000 / 3000 = 20 / 3 = 6.6 µm</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>If you know someone with a disease that might be cured by stem cell therapy then you might be a supporter of this research. You probably also know that some other people have deep concerns.</p><p>Which of the following is<strong> not </strong>a potential benefit of the use of stem cells?</p></div><div class="q-answer"><p><label class="radio"><input class="c" type="radio"> Stem cell research is a cheaper treatment than many other treatments.</label></p><p><label class="radio"><input type="radio"> Stem cells could provide a treatment for Stargadts disease.</label></p><p><label class="radio"><input type="radio"> Damaged nerve cells could be replaced by stem cells.</label></p><p><label class="radio"><input type="radio"> Human tissues could be grown to replace damaged tissues.</label></p></div><div class="q-explanation"><p>There are ethical concerns about the use of embryo stem cells.</p><p>The research is expensive, and potential treatments are also likely to be expensive, and probably not available to all.</p><p>Many people who are against stem cells say that it is because cells are taken from human embryos, which have the potential for human live, and should be protected. There are other sources of stem cells, they argue.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div> </div> </div> <div class="modal-footer slide-quiz-actions"> <div class=""> <div class="pull-left pull-xs-none mb-xs-3"> <button class="btn btn-default d-xs-none btn-prev"> <i class="fa fa-arrow-left"></i> Prev </button> </div> <div class="pull-right pull-xs-none"> <button class="btn btn-success btn-xs-block text-xs-center btn-results" style="display: none"> <i class="fa fa-bar-chart"></i> Check Results </button> <button class="btn btn-default d-xs-none btn-next"> Next <i class="fa fa-arrow-right"></i> </button> <button class="btn btn-default btn-xs-block text-xs-center btn-close" data-dismiss="modal" style="display: none"> Close </button> </div> </div> </div> </div> </div></div> <p>Click the '+' symbol to open the next quiz.</p> <div class="panel panel-expandable panel-green"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Multiple choice quiz 2</p> </div> </div> <div class="panel-body"> <div> <br><a class="btn btn-primary btn-block text-center" data-toggle="modal" href="#686f94ed"><i class="fa fa-play"></i> START QUIZ!</a><div class="modal fade modal-slide-quiz" id="686f94ed"> <div class="modal-dialog" style="width: 95vw; max-width: 960px"> <div class="modal-content"> <div class="modal-header slide-quiz-title"> <h4 id="header-11"> 1.1 Intro to cells (2) <strong class="q-number pull-right"> <span class="counter">1</span>/<span class="total">1</span> </strong> <small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h4> </div> <div class="modal-body p-xs-3"> <div class="slide-quiz" data-stats="5-617-486" style="opacity: 0"> <div class="exercise shadow-bottom"><div class="q-question"><p>Which phrases most accurately describe a multicellular organism?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> Many cells of varying types with no cell differentiation nor replacement.</label></p><p><label class="radio"><input class="c" type="radio"> Many cells of varying types with cell differentiation and replacement.</label></p><p><label class="radio"><input type="radio"> Many cells of the same type with cell replacement but no cell differentiation.</label></p><p><label class="radio"><input type="radio"> Many cells of the same type with cell differentiation and replacement.</label></p></div><div class="q-explanation"><p>Comment: The multicellular condition allows for differentiation into cells of different types and also replacement of cells when injured or damaged.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Which two processes are involved in cell differentiation?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> No change in gene expression or organelle function.</label></p><p><label class="radio"><input type="radio"> No change in gene expression and a change in function of organelles.</label></p><p><label class="radio"><input type="radio"> A change in gene expression and the formation of new organelles.</label></p><p><label class="radio"><input class="c" type="radio"> A change in gene expression causing some organelles to produce different products.</label></p></div><div class="q-explanation"><p>Comment: During differentiation genes may be activated or repressed causing the formation of different proteins by the ribosomes but other organelles such as mitochondria continue to function in the same way</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Which is the best definition of a tissue?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> A group of identical cells carrying out more than one function.</label></p><p><label class="radio"><input type="radio"> A group of identical cells carrying out one function.</label></p><p><label class="radio"><input class="c" type="radio"> A group of one or more types of cells carrying out one or several related functions.</label></p><p><label class="radio"><input type="radio"> A small number of cells with one function.</label></p></div><div class="q-explanation"><p>Comment:Tissues may have one or several cell types and one or more functions</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Which of the following could be used to distinguish a living from a non-living object?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> Can utilise energy</label></p><p><label class="radio"><input class="c" type="radio"> Can respire</label></p><p><label class="radio"><input type="radio"> Can move</label></p><p><label class="radio"><input type="radio"> Can produce energy</label></p></div><div class="q-explanation"><p>Comment: Inanimate objects can move, produce and utilise energy but the process of respiration is exclusive to living systems</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Human red blood cells are circular and 0.6 μm in diameter. A photograph of a red blood cell is shown as an illustration in a book with a diameter of 1.2mm. What is the magnification of the diagram?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> 400 X</label></p><p><label class="radio"><input type="radio"> 20 X</label></p><p><label class="radio"><input class="c" type="radio"> 2000 X</label></p><p><label class="radio"><input type="radio"> 0.5 X</label></p></div><div class="q-explanation"><p>Comment: Convert 1.2 mm into μm by multiplying x 1000 = 1200 μm (so that both units are the same). Then you can see that 0.6 x 2000 = 1200. Or use the formula Magnification = Image size/true size. If the photograph is larger than the cell, the magnification could not be 0.5x which would make it smaller. Eliminate obviously incorrect answers.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Which is the correct order of SI units, beginning with the largest?</p></div><div class="q-answer"><p><label class="radio"><input class="c" type="radio"> m mm μm nm</label></p><p><label class="radio"><input type="radio"> m mm nm μm</label></p><p><label class="radio"><input type="radio"> mm m μm nm</label></p><p><label class="radio"><input type="radio"> μm nm m mm</label></p></div><div class="q-explanation"><p>Comment: SI units always have a differential of 1000. The unit without the prefix is the standard SI unit (metre, m). B and D are clearly wrong, eliminate those answers first.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The image below is of <em>Dracaena</em> leaf upper epidermis cells.<br>Which of the following is the best estimate of the length (from top to bottom) of an epidermal cell?<br><img alt="" src="../../images/01_cells/epidermis_cells.jpg" style="width: 250px; height: 323px;"></p></div><div class="q-answer"><p><label class="radio"><input type="radio"> 0.007 mm</label></p><p><label class="radio"><input type="radio"> 30 μm</label></p><p><label class="radio"><input type="radio"> 0.7 mm</label></p><p><label class="radio"><input class="c" type="radio"> 70 μm</label></p></div><div class="q-explanation"><p>Comment: The cells are approximately the same height as the scale bar length. So 70µm is the best estimate.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>If you wished to gain a more precise estimate of the size of the epidermal cells in the photo above, which phrase best describes the reason that you would count several rows and not only one?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> Taking repeats is more accurate.</label></p><p><label class="radio"><input class="c" type="radio"> Counting repeats and calculating the mean gives more accurate results.</label></p><p><label class="radio"><input type="radio"> I might make a mistake.</label></p><p><label class="radio"><input type="radio"> They are not easy to count.</label></p></div><div class="q-explanation"><p>Comment: Repeats are used to calculate means when there is variation (in this case, of length). A,B and C could also be considered correct but D is the most valid answer.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div> </div> </div> <div class="modal-footer slide-quiz-actions"> <div class=""> <div class="pull-left pull-xs-none mb-xs-3"> <button class="btn btn-default d-xs-none btn-prev"> <i class="fa fa-arrow-left"></i> Prev </button> </div> <div class="pull-right pull-xs-none"> <button class="btn btn-success btn-xs-block text-xs-center btn-results" style="display: none"> <i class="fa fa-bar-chart"></i> Check Results </button> <button class="btn btn-default d-xs-none btn-next"> Next <i class="fa fa-arrow-right"></i> </button> <button class="btn btn-default btn-xs-block text-xs-center btn-close" data-dismiss="modal" style="display: none"> Close </button> </div> </div> </div> </div> </div></div> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <hr> <h3 id="header-12">Drag and drop activities<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505946" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p>Test your construction of biological explanations using the drag and drop questions below.</p> <p><strong>The multicellular nature of many organisms.</strong></p> <div class="tib-quiz" data-stats="5-818-486"><p>Drag and drop the correct term into the gap to describe differentiation.</p><div class="label label-default q-number">1</div><div class="exercise shadow-bottom"><div class="q-question"><p> </p><p class="gap-drop"> <span class="q-text-draggable draggable" draggable="true">functions</span> <span class="q-text-draggable draggable" draggable="true">proteins</span> <span class="q-text-draggable draggable" draggable="true">tissues</span> <span class="q-text-draggable draggable" draggable="true">differentiation</span> <span class="q-text-draggable draggable" draggable="true">gene</span> <span class="q-text-draggable draggable" draggable="true">expression</span> <span class="q-text-draggable draggable" draggable="true">types </span> <span class="q-text-draggable draggable" draggable="true">stem</span> </p></div><div class="q-answer"><p><span calibri="" style="font-size:11.0pt;line-height:107%;
font-family:">In a multicellular organism, there are specialised <input type="text" style="height: auto;" data-c="tissues"> <span class="review"></span> that develop from <input type="text" style="height: auto;" data-c="stem"> <span class="review"></span> cells by <input type="text" style="height: auto;" data-c="differentiation"> <span class="review"></span> . Differentiation involves altering gene <input type="text" style="height: auto;" data-c="expression"> <span class="review"></span> , genes that code for <input type="text" style="height: auto;" data-c="proteins"> <span class="review"></span> needed for cell development are expressed in the cells, hence the cells have varied <input type="text" style="height: auto;" data-c="functions"> <span class="review"></span> due to the <input type="text" style="height: auto;" data-c="types "> <span class="review"></span> of protein synthesised. </span></p></div><div class="q-explanation"><p>Correct terminology is needed to discuss cell development.</p></div><div class="actions"><span class="score" data-score="0"></span><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="totals"><span class="score"></span><button class="btn btn-success btn-block text-center check-total"><i class="fa fa-check-square-o"></i> Check</button></div></div><hr> </div> <p>Click the '+' symbol to open the next explanation.</p> <div class="panel panel-expandable panel-green"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Drag and drop explanation of the limited size of cells</p> </div> </div> <div class="panel-body"> <div> <p><strong>Stem cells </strong></p> <div class="tib-quiz" data-stats="5-819-486"><div class="label label-default q-number">1</div><div class="exercise shadow-bottom"><div class="q-question"><p> </p><p class="gap-drop"> <span class="q-text-draggable draggable" draggable="true"> inefficient</span> <span class="q-text-draggable draggable" draggable="true">volume</span> <span class="q-text-draggable draggable" draggable="true">exchanging</span> <span class="q-text-draggable draggable" draggable="true">oxygen</span> <span class="q-text-draggable draggable" draggable="true">surface area</span> <span class="q-text-draggable draggable" draggable="true">plasma</span> <span class="q-text-draggable draggable" draggable="true">materials</span> </p></div><div class="q-answer"><p><span calibri="" style="font-size:11.0pt;line-height:107%;
font-family:">Cells are limited in size by their efficiency in exchanging <input type="text" style="height: auto;" data-c="materials"> <span class="review"></span> through the <input type="text" style="height: auto;" data-c="plasma"> <span class="review"></span> membrane As the cell's <input type="text" style="height: auto;" data-c="volume"> <span class="review"></span> increases, so does its need for materials such as <input type="text" style="height: auto;" data-c="oxygen"> <span class="review"></span> or nutrients. However, the larger the cell, the lower the <input type="text" style="height: auto;" data-c="surface area"> <span class="review"></span> to volume ratio and the cell becomes <input type="text" style="height: auto;" data-c=" inefficient"> <span class="review"></span> in <input type="text" style="height: auto;" data-c="exchanging"> <span class="review"></span> materials with the outside of the cell.</span></p></div><div class="q-explanation"><p>A cube of side 1x1x1mm has a surface area of 6mm<sup>2</sup>. It has a volume of 1mm<sup>3</sup>.</p><p>A cube of side 3x3x3mm has a surface area of 54mm<sup>2</sup>. It has a volume of 27mm<sup>3</sup>, 9 times the surface area but 27 times the volume of the smaller "cell".</p></div><div class="actions"><span class="score" data-score="0"></span><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="totals"><span class="score"></span><button class="btn btn-success btn-block text-center check-total"><i class="fa fa-check-square-o"></i> Check</button></div></div><hr> </div> </div> <div class="panel-footer"> <div> </div> </div> </div> <div class="panel panel-expandable panel-green"> <div class="panel-heading"><a class="expander" href="#"><span class="fa fa-plus"></span></a> <div> <p>Drag and drop explanation of stem cell therapy and ethics</p> </div> </div> <p><strong> Ethics</strong></p> <div class="panel-body"> <div> <div class="tib-quiz" data-stats="5-820-486"><p><strong>The ethical use of stem cells.</strong></p><div class="tib-quiz" data-stats="5-818-486"><p>Drag and drop the correct term into the gap to describe sources, uses and etics of stem cell therapy.</p></div><div class="label label-default q-number">1</div><div class="exercise shadow-bottom"><div class="q-question"><p> </p><p class="gap-drop"> <span class="q-text-draggable draggable" draggable="true">ethical</span> <span class="q-text-draggable draggable" draggable="true">embryos</span> <span class="q-text-draggable draggable" draggable="true">Stargardt's </span> <span class="q-text-draggable draggable" draggable="true">foetus</span> <span class="q-text-draggable draggable" draggable="true">umbilical cord tissue</span> <span class="q-text-draggable draggable" draggable="true">divide</span> <span class="q-text-draggable draggable" draggable="true">therapeutic</span> <span class="q-text-draggable draggable" draggable="true">differentiate</span> </p></div><div class="q-answer"><p>Stem cells are able to <input type="text" style="height: auto;" data-c="divide"> <span class="review"></span> by mitosis and <input type="text" style="height: auto;" data-c="differentiate"> <span class="review"></span> into mature cells. This makes them have many <input type="text" style="height: auto;" data-c="therapeutic"> <span class="review"></span> uses, such as the treatment of <input type="text" style="height: auto;" data-c="Stargardt's "> <span class="review"></span> disease. Stem cells can be obtained from <input type="text" style="height: auto;" data-c="umbilical cord tissue"> <span class="review"></span> and from an adult patients own cells. They can also be obtained from <input type="text" style="height: auto;" data-c="embryos"> <span class="review"></span> 3 to 5 days sfter fertilisation (usually unused embryos from fertility treatment) but this raises <input type="text" style="height: auto;" data-c="ethical"> <span class="review"></span> issues as it involves the destruction of a <input type="text" style="height: auto;" data-c="foetus"> <span class="review"></span> .</p></div><div class="q-explanation"><p>You need to know uses, sources and ethical issues of stem cell therapy</p></div><div class="actions"><span class="score" data-score="0"></span><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="totals"><span class="score"></span><button class="btn btn-success btn-block text-center check-total"><i class="fa fa-check-square-o"></i> Check</button></div></div><hr> </div> </div> <div class="panel-footer"> <div> </div> </div> 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