{"id":256618,"date":"2025-07-16T11:20:01","date_gmt":"2025-07-16T11:20:01","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=256618"},"modified":"2025-07-16T11:20:05","modified_gmt":"2025-07-16T11:20:05","slug":"create-a-punnett-square-to-determine-the-possibility-of-a-couple-having-a-color-blind-child-if-the-mother-is-color-blind-but-the-father-has-normal-vision","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/16\/create-a-punnett-square-to-determine-the-possibility-of-a-couple-having-a-color-blind-child-if-the-mother-is-color-blind-but-the-father-has-normal-vision\/","title":{"rendered":"Create a Punnett square to determine the possibility of a couple having a color-blind child if the mother is color blind but the father has normal vision."},"content":{"rendered":"\n

Create a Punnett square to determine the possibility of a couple having a color-blind child if the mother is color blind but the father has normal vision. HINT: Use Xb to indicate an X with the color-blindness trait.<\/p>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

Punnett Square for Color Blindness<\/strong><\/h3>\n\n\n\n

Let\u2019s define the alleles:<\/p>\n\n\n\n

    \n
  • X<\/strong> = normal vision X chromosome<\/li>\n\n\n\n
  • Xb<\/strong> = X chromosome with color blindness<\/li>\n\n\n\n
  • Y<\/strong> = Y chromosome (does not carry the gene for color vision)<\/li>\n<\/ul>\n\n\n\n

    Parents’ Genotypes<\/strong><\/h3>\n\n\n\n
      \n
    • Mother<\/strong> is color blind: XbXb<\/strong><\/li>\n\n\n\n
    • Father<\/strong> has normal vision: XY<\/strong><\/li>\n<\/ul>\n\n\n\n

      Punnett Square<\/strong><\/h3>\n\n\n\n
      <\/th>X (Father)<\/th>Y (Father)<\/th><\/tr><\/thead>
      Xb (Mother)<\/td>XbX<\/td>XbY<\/td><\/tr>
      Xb (Mother)<\/td>XbX<\/td>XbY<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

      Results<\/strong><\/h3>\n\n\n\n
        \n
      • XbX<\/strong> = Female carrier (normal vision but carries the gene)<\/li>\n\n\n\n
      • XbY<\/strong> = Male child with color blindness<\/li>\n<\/ul>\n\n\n\n

        Offspring Possibilities<\/strong><\/h3>\n\n\n\n
          \n
        • 50% chance of XbX<\/strong> = daughters with normal vision but carriers<\/li>\n\n\n\n
        • 50% chance of XbY<\/strong> = sons who are color blind<\/li>\n<\/ul>\n\n\n\n
          \n\n\n\n

          Explanation<\/strong><\/h3>\n\n\n\n

          Color blindness is a sex-linked recessive trait<\/strong>, meaning the gene responsible for it is found on the X chromosome. Males only have one X chromosome (XY), so if they inherit the Xb chromosome, they will express the trait because there is no second X chromosome to mask it. Females have two X chromosomes (XX), so they need two copies of the Xb allele to be color blind. If a female has one normal X and one Xb, she is a carrier but not color blind herself.<\/p>\n\n\n\n

          In this case, the mother is color blind<\/strong>, which means her genotype must be XbXb<\/strong>. This is because females need two Xb chromosomes to express color blindness. The father has normal vision<\/strong>, so his genotype must be XY<\/strong> with a normal X chromosome.<\/p>\n\n\n\n

          To determine the possible combinations of their children\u2019s genotypes, we use a Punnett square. When we cross XbXb with XY, each child will inherit one Xb chromosome from the mother. The father can contribute either an X or a Y chromosome. If the child inherits his X, the child will be a carrier daughter (XbX)<\/strong>. If the child inherits his Y, the result is a color-blind son (XbY)<\/strong>.<\/p>\n\n\n\n

          Therefore, there is a 50% chance of having a color-blind son<\/strong>, and a 50% chance of having a daughter who is a carrier<\/strong>. All daughters will be carriers, and no daughters will be color blind<\/strong>, but all sons will be affected<\/strong> if they receive the Xb chromosome.<\/p>\n\n\n\n

          \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

          Create a Punnett square to determine the possibility of a couple having a color-blind child if the mother is color blind but the father has normal vision. HINT: Use Xb to indicate an X with the color-blindness trait. The Correct Answer and Explanation is: Punnett Square for Color Blindness Let\u2019s define the alleles: Parents’ Genotypes […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-256618","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256618","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=256618"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256618\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=256618"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=256618"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=256618"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}