{"id":2010,"date":"2020-07-19T07:57:40","date_gmt":"2020-07-19T07:57:40","guid":{"rendered":"https:\/\/murreeroad.org\/Biology10\/?p=2010"},"modified":"2020-07-19T07:57:40","modified_gmt":"2020-07-19T07:57:40","slug":"q-12-define-variations-discuss-their-sources-and-types","status":"publish","type":"post","link":"https:\/\/murreeroad.org\/Biology10\/q-12-define-variations-discuss-their-sources-and-types\/","title":{"rendered":"Q.12 Define variations. Discuss their sources and types."},"content":{"rendered":"<p><strong>Q.12 Define variations. Discuss their sources and types.<\/strong><br \/>\n<strong>Answer:<\/strong><br \/>\n<strong>Definition<\/strong><br \/>\nDifferences shown by the individual of same species are called as variations. Sources of variations<br \/>\n<strong>(a) Genetic Recombination <\/strong><br \/>\nThe genetic recombination produced through crossing over results in gametes with variations.<br \/>\n<strong>(b) Mutation <\/strong><br \/>\nMutation (changes in DNA) are important source of variations.<br \/>\n<strong>(c) Combination of Sperm with egg <\/strong><br \/>\nDuring fertilization, one of the millions of sperms combines with a single egg. The chance involved in this combination also act as the source of variations.<br \/>\n<strong>(d) Gene Flow <\/strong><br \/>\nMovement of genes from one population to another is also an important source of variations.<br \/>\n<strong>(e) Combination of Chromosomes\u00a0<\/strong><br \/>\nVariations are also caused by different combinations of chromosomes in gametes and then in zygote.<br \/>\n<strong>Types of Variations<\/strong><br \/>\n<strong>(i) Continuous variations <\/strong><br \/>\nIn continuous variations, the phenotypes show a complete range of measurements from one extreme to the other.&#8221; Such variations are controlled by many genes and also affected by environmental factors.<br \/>\n<strong>Examples<\/strong><br \/>\nHeight in Man<br \/>\nWeight in Man<br \/>\nFeet size in Man<br \/>\nIntelligence in Man<br \/>\n<strong>Height in Man <\/strong><br \/>\nIn every human population, the individuals have range of heights (from very small to tall). No population can show only two or three distinct heights.<br \/>\n<strong>(\u00fc) Discontinuous variations <\/strong><br \/>\nDiscontinuous variations show distinct phenotypes. The phenotypes of such variations cannot be measured. The individuals of population have distinct phenotypes which can easily be distinguished from each other, Discontinuous variations are controlled by the allele of a single gene pair. Environment has no effect on such variations.<br \/>\n<strong>Example<\/strong><br \/>\n<strong>Blood groups in Man<\/strong><br \/>\nIn human population, an individual has one of the four distinct phenotypes (blood groups) and cannot have in between. &#8221;<br \/>\n<a href=\"https:\/\/murreeroad.org\/Biology10\/unit-15-inheritance-long-questions\/\"><img loading=\"lazy\" class=\"alignnone size-full wp-image-1462 aligncenter\" src=\"https:\/\/murreeroad.org\/Biology10\/wp-content\/uploads\/2020\/06\/back_button.png\" alt=\"\" width=\"150\" height=\"45\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Q.12 Define variations. Discuss their sources and types. Answer: Definition Differences shown by the individual of same species are called as variations. Sources of variations (a) Genetic Recombination The genetic recombination produced through crossing over results in gametes with variations. (b) Mutation Mutation (changes in DNA) are important source of variations. (c) Combination of Sperm&hellip;&nbsp;<a href=\"https:\/\/murreeroad.org\/Biology10\/q-12-define-variations-discuss-their-sources-and-types\/\" class=\"\" rel=\"bookmark\">Read More &raquo;<span class=\"screen-reader-text\">Q.12 Define variations. Discuss their sources and types.<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[26],"tags":[],"_links":{"self":[{"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/posts\/2010"}],"collection":[{"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/comments?post=2010"}],"version-history":[{"count":1,"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/posts\/2010\/revisions"}],"predecessor-version":[{"id":2011,"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/posts\/2010\/revisions\/2011"}],"wp:attachment":[{"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/media?parent=2010"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/categories?post=2010"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/murreeroad.org\/Biology10\/wp-json\/wp\/v2\/tags?post=2010"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}