{"id":3533,"date":"2025-07-26T03:09:15","date_gmt":"2025-07-26T03:09:15","guid":{"rendered":"https:\/\/odeacademy.in\/?p=3533"},"modified":"2026-03-16T16:44:22","modified_gmt":"2026-03-16T16:44:22","slug":"biology-notes-for-competitive-exams","status":"publish","type":"post","link":"https:\/\/thequickknowledge.com\/exam\/biology-notes-for-competitive-exams\/","title":{"rendered":"Biology &#8211; Notes for Competitive Exams | General Science"},"content":{"rendered":"<h4 style=\"text-align: center;\"><strong>Biology Notes<\/strong><\/h4>\n<hr \/>\n<h5><strong>Cell, The Fuldamental Unit of Life<img fetchpriority=\"high\" decoding=\"async\" class=\"wp-image-3583 alignright\" src=\"https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-02.jpg\" alt=\"\" width=\"326\" height=\"272\" srcset=\"https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-02.jpg 730w, https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-02-300x250.jpg 300w\" sizes=\"(max-width: 326px) 100vw, 326px\" \/><\/strong><\/h5>\n<p>Cell shape and size vary depending on their function. For example, Amoeba can change its shape, while nerve cells have a fixed shape.<\/p>\n<ul>\n<li>Unicellular organisms (e.g., Amoeba, Chlamydomonas, Paramoecium) consist of a single cell.<\/li>\n<li>multicellular organisms (e.g., plants, animals) are made of many cells with specialized functions.<\/li>\n<\/ul>\n<p><strong>Important Discoveries:<\/strong><\/p>\n<ul>\n<li><strong>Robert Hooke<\/strong> (1665) first observed (dead) cells in a cork slice,<\/li>\n<li><strong>Leeuwenhoek (1674)<\/strong> \u2013 free-living cells in pond water.<\/li>\n<li><strong>Robert Brown (1831)<\/strong> \u2013 discovered the <strong>nucleus<\/strong>.<\/li>\n<li><strong>Purkinje (1839)<\/strong> \u2013 coined the term <strong>protoplasm<\/strong>.<\/li>\n<li><strong>Schleiden &amp; Schwann<\/strong> \u2013 proposed the <strong>cell theory<\/strong>.<\/li>\n<li><strong>Virchow (1855)<\/strong> \u2013 cells arise from <strong>pre-existing cells<\/strong>.<\/li>\n<\/ul>\n<p><strong>Cell Organelles &#8211; <\/strong>Cells perform life processes with the help of cell organelles,\u00a0 All cells contain three basic components: <strong>1)<\/strong> Plasma membrane (or cell membrane), <strong>2) <\/strong>Nucleus<strong>, 3) <\/strong>Cytoplasm.<\/p>\n<ul>\n<li><strong>Plasma membrane (<\/strong>Cell Membrane<strong>)<\/strong> is the cell&#8217;s outer covering and is selectively permeable, allowing certain substances to pass in or out.<strong> Diffusion<\/strong> moves substances from high to low concentration, while <strong>osmosis<\/strong> is the diffusion of water through the membrane. Depending on the surrounding solution, cells may swell (hypotonic), remain unchanged (isotonic), or shrink (hypertonic).<\/li>\n<li><strong>Nucleus &#8211; <\/strong>Cell\u2019s control center. Enclosed by nuclear membrane with pores. Contains chromosomes (DNA + proteins), responsible for heredity. In non-dividing cells, DNA exists as chromatin; condenses into chromosomes during division. <strong>Eukaryotic cells<\/strong> \u2013 Have a well-defined nucleus. <strong>Prokaryotic cells<\/strong> (e.g., bacteria) \u2013 Lack nuclear membrane; contain nucleoid.<\/li>\n<li><strong>Cytoplasm &#8211; <\/strong>Fluid inside the plasma membrane. Contains organelles (e.g., mitochondria, chloroplasts). In prokaryotes: organelles are unorganized, not membrane-bound. In eukaryotes: organelles are membrane-bound.<\/li>\n<li><strong>Cell Wall &#8211; <\/strong>Found in plant cells, outside plasma membrane. Made of cellulose; provides rigidity and support. Plasmolysis: cell contents shrink away from wall when water is lost. Prevents bursting in dilute solutions (osmotic balance).<\/li>\n<\/ul>\n<table>\n<thead>\n<tr>\n<th><strong>Cell Organelles<\/strong><\/th>\n<th><strong>Function<\/strong><\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: center;\"><strong>Nucleus<\/strong><\/td>\n<td>control center of the cell; it contains DNA and regulates all cellular activities.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Mitochondria<\/strong><\/td>\n<td>Powerhouse of the cell, produce energy ATP (Adenosine Triphosphate) \u2013 energy currency of the cell, Contains its own DNA and ribosomes \u2013 can make proteins.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Ribosome<\/strong><\/td>\n<td>responsible for protein synthesis<\/td>\n<\/tr>\n<tr>\n<td>\n<p style=\"text-align: center;\"><strong>Endoplasmic Reticulum (<\/strong>ER<strong>)<\/strong><\/p>\n<\/td>\n<td>ER is two types: <strong>Rough ER<\/strong> has ribosomes and helps in protein synthesis. <strong>Smooth ER<\/strong> has no ribosomes; synthesizes lipids and helps in detoxification.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Golgi Apparatus<\/strong><\/td>\n<td>packages proteins &amp; other substances, sends them inside\/outside the cell.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Lysosomes<\/strong><\/td>\n<td>Digest unwanted substances, known as the cell&#8217;s waste disposal system.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Vacuole<\/strong><\/td>\n<td>store water, food, and waste materials; they are larger in plant cells. Maintain turgidity in plant cells. In unicellular organisms (e.g., Amoeba), vacuoles store food and help remove waste.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Cytoplasm<\/strong><\/td>\n<td>A jelly-like fluid where all the organelles float and function.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Chloroplast<\/strong><\/td>\n<td>Found only in plants, perform photosynthesis, making food using sunlight.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\"><strong>Plastids<\/strong><\/td>\n<td>Found only in plant cells. Internal structure like mitochondria; also have DNA and ribosomes. Two main types:<\/p>\n<ul>\n<li>Chromoplasts: contain chlorophyll, perform photosynthesis.<\/li>\n<li>Leucoplasts: store starch, oils, proteins.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h5 data-start=\"234\" data-end=\"298\"><strong data-start=\"242\" data-end=\"298\">Differences Between Prokaryotic and Eukaryotic Cells<\/strong><\/h5>\n<div class=\"_tableContainer_80l1q_1\">\n<div tabindex=\"-1\">\n<table>\n<thead>\n<tr>\n<th>Feature<\/th>\n<th>Prokaryotic Cell<\/th>\n<th>Eukaryotic Cell<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: center;\">Size<\/td>\n<td style=\"text-align: center;\">Small (1\u201310 \u00b5m)<\/td>\n<td style=\"text-align: center;\">Large (5\u2013100 \u00b5m)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">Nuclear Region<\/td>\n<td style=\"text-align: center;\">Not well-defined, called nucleoid<\/td>\n<td style=\"text-align: center;\">Well-defined, enclosed in nuclear membrane<\/td>\n<\/tr>\n<tr>\n<td>Chromosome<\/td>\n<td style=\"text-align: center;\">Single<\/td>\n<td style=\"text-align: center;\">Multiple<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\">Organelles<\/td>\n<td style=\"text-align: center;\">Membrane-bound organelles absent<\/td>\n<td style=\"text-align: center;\">Membrane-bound organelles present<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"_tableWrapper_80l1q_14 group flex w-fit flex-col-reverse\" tabindex=\"-1\">\n<p data-start=\"885\" data-end=\"910\"><img decoding=\"async\" class=\" wp-image-3585 aligncenter\" src=\"https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-08-1024x548.jpg\" alt=\"\" width=\"785\" height=\"420\" srcset=\"https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-08-1024x548.jpg 1024w, https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-08-300x161.jpg 300w, https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-08-768x411.jpg 768w, https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-08.jpg 1269w\" sizes=\"(max-width: 785px) 100vw, 785px\" \/><\/p>\n<p data-start=\"885\" data-end=\"910\"><strong data-start=\"890\" data-end=\"910\">Cell Division &#8211; <\/strong>Process by which cells grow, repair, and reproduce. Two types: <strong>(01) Mitosis<\/strong><span style=\"font-size: 16px;\">: makes two identical daughter cells \u2013 used for <\/span>growth and repair<span style=\"font-size: 16px;\">. <strong>(02) <\/strong><\/span><strong style=\"font-size: 16px;\" data-start=\"1070\" data-end=\"1081\">Meiosis<\/strong><span style=\"font-size: 16px;\">: makes four non-identical daughter cells with <\/span>half the chromosomes<span style=\"font-size: 16px;\"> \u2013 used for forming <\/span>gametes<span style=\"font-size: 16px;\">.<\/span><\/p>\n<p><img decoding=\"async\" class=\" wp-image-3587 aligncenter\" src=\"https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-10-1024x302.jpg\" alt=\"\" width=\"726\" height=\"214\" srcset=\"https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-10-1024x302.jpg 1024w, https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-10-300x88.jpg 300w, https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-10-768x226.jpg 768w, https:\/\/thequickknowledge.com\/exam\/wp-content\/uploads\/2025\/07\/iesc105-10.jpg 1338w\" sizes=\"(max-width: 726px) 100vw, 726px\" \/><\/p>\n<p>k<\/p>\n<\/div>\n<\/div>\n<hr \/>\n<p><strong>What is plasmolysis?\u00a0 <\/strong>(A) Swelling of cell in salt solution\u00a0 (B) Shrinkage of cell content away from cell wall\u00a0 (C) Division of cell\u00a0 (D) Entry of water into cell<\/p>\n<p><strong>Which of the following is absent in prokaryotic cells? <\/strong>(A) Nucleoid\u00a0 (B) Cell wall\u00a0 (C) Membrane-bound organelles\u00a0 (D) Cytoplasm<\/p>\n<p><strong>What is the function of the plasma membrane? <\/strong>(A) Provides energy to the cell\u00a0 (B) Allows selective substances to pass\u00a0 (C) Stores food\u00a0 (D) Helps in cell division<\/p>\n<p><strong>Which process allows oxygen to enter the cell?\u00a0 <\/strong>(A) Active transport\u00a0 (B) Osmosis\u00a0 (C) Diffusion\u00a0 (D) Evaporation<\/p>\n<p data-start=\"1742\" data-end=\"2018\"><strong data-start=\"1742\" data-end=\"1856\">What is the function of Rough Endoplasmic Reticulum (RER)? <\/strong>(A) Lipid synthesis (B) Protein synthesis (C) DNA replication (D) Enzyme breakdown<\/p>\n<p data-start=\"2029\" data-end=\"2294\"><strong data-start=\"2029\" data-end=\"2166\">Which cell organelle is responsible for packaging and transporting proteins? <\/strong>(A) Lysosome (B) Mitochondria (C) Golgi apparatus (D) Ribosome<\/p>\n<p data-start=\"2305\" data-end=\"2581\"><strong data-start=\"2305\" data-end=\"2365\">The function of lysosomes is to: <\/strong>(A) Produce ATP (B) Synthesize proteins (C) Digest waste and old organelles (D) Control cell division<\/p>\n<p data-start=\"2875\" data-end=\"3186\"><strong data-start=\"2875\" data-end=\"3001\">What is the main role of smooth endoplasmic reticulum (SER)? <\/strong>(A) Protein synthesis (B) DNA formation (C) Lipid synthesis and detoxification (D) Cell division<\/p>\n<p data-start=\"1627\" data-end=\"1890\"><strong data-start=\"1627\" data-end=\"1776\">Which of the following organelles contain their own DNA and ribosomes? <\/strong>(A) Mitochondria and Lysosome (B) Mitochondria and Plastids (C) Plastids and Golgi body (D) Nucleus and Vacuole<\/p>\n<p data-start=\"1897\" data-end=\"2114\"><strong data-start=\"1897\" data-end=\"2017\">What is the main function of vacuoles in plant cells? <\/strong>(A) Photosynthesis (B) Respiration (C) Protein synthesis (D) Storage and maintaining turgidity<\/p>\n<p data-start=\"2121\" data-end=\"2325\"><strong data-start=\"2121\" data-end=\"2268\">What type of cell division is responsible for the formation of gametes? <\/strong>(A) Mitosis (B) Binary Fission (C) Meiosis (D) Budding<\/p>\n<hr \/>\n<p>For more Please visit Our YouTube Channel <span style=\"color: #ff0000;\"><strong>@ODEAcademy \u25b6\ufe0f<\/strong><\/span><\/p>\n<hr \/>\n<p><span style=\"color: #ff0000;\"><strong>Related Links<\/strong><\/span><\/p>\n<ul>\n<li><a href=\"https:\/\/thequickknowledge.com\/exam\/general-science-mcqs\/\">General Science MCQs for Competitive Exams<\/a> \ud83d\udd17<\/li>\n<li><a href=\"https:\/\/thequickknowledge.com\/exam\/general-science\/\">General Science Complete Study Material for Competitive Exams<\/a> \ud83d\udd17<\/li>\n<\/ul>\n<hr \/>\n<p><strong><a href=\"https:\/\/thequickknowledge.com\/exam\/general-science\/\">General Science<\/a>, <a href=\"https:\/\/thequickknowledge.com\/exam\/study-materials\/\">Study Materials<\/a>, <a href=\"https:\/\/thequickknowledge.com\/exam\/current-affairs\/\">Current Affairs<\/a>, <a href=\"https:\/\/thequickknowledge.com\/exam\/practice-questions\/\">Practice Questions<\/a>,\u00a0<\/strong><\/p>\n<hr \/>\n<p style=\"text-align: center;\"><strong>For More Updates ! Join ODEAcademy <a href=\"https:\/\/whatsapp.com\/channel\/0029VbB3TFEI1rcs7QmbSv2H\"><span style=\"color: #00ff00;\">WhatsApp <\/span><\/a>and <a href=\"https:\/\/t.me\/ODEAcademy\"><span style=\"color: #00ff00;\"><span style=\"color: #3366ff;\">Telegram <\/span><\/span><\/a>Channel<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Biology Notes Cell, The Fuldamental Unit of Life Cell shape and size vary depending on their function. For example, Amoeba can change its shape, while nerve cells have a fixed shape. Unicellular organisms (e.g., Amoeba, Chlamydomonas, Paramoecium) consist of a single cell. multicellular organisms (e.g., plants, animals) are made of many cells with specialized functions. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":4146,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"no-sidebar","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":"disabled","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","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":[137],"tags":[138],"class_list":["post-3533","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-general-science","tag-general-science-notes"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/posts\/3533","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/comments?post=3533"}],"version-history":[{"count":12,"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/posts\/3533\/revisions"}],"predecessor-version":[{"id":3550,"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/posts\/3533\/revisions\/3550"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/media\/4146"}],"wp:attachment":[{"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/media?parent=3533"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/categories?post=3533"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thequickknowledge.com\/exam\/wp-json\/wp\/v2\/tags?post=3533"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}