Heredity And Genetics
Overview
Two parents with brown eyes can have a blue-eyed child; two parents of blood group A can have a child of blood group O; a condition can appear in a grandson but skip his mother entirely. None of this is random chance. It follows directly from how alleles are inherited, and a genetic diagram lets you predict it with confidence.
This lesson covers the vocabulary of inheritance, how to use genetic diagrams to predict the outcomes of a cross including sex determination and multiple-allele traits such as blood group, how to read a family pedigree, and the inheritance of named genetic conditions including one, cystic fibrosis, that can now be treated with gene therapy.
Objectives
- Know that genes exist in alternative forms called alleles which give rise to differences in inherited characteristics
- Know the meaning of the terms dominant, recessive, homozygous, heterozygous, phenotype, genotype, co-dominance, diploid and haploid
- Know that the sex of a person is controlled by one pair of chromosomes, XX in a female and XY in a male
- Explain how the sex of offspring is determined at fertilisation using a genetic diagram
- Understand that random fertilisation produces genetic variation of offspring
- Understand the role of multiple alleles in the inheritance of ABO blood groups
- Understand patterns of monohybrid inheritance using a genetic diagram and the probabilities of outcomes
- Understand how to interpret family pedigrees
- Describe the causes and effects of inherited conditions such as haemophilia and red-green colour blindness (sex-linked inheritance), polydactyly (dominant allele) and cystic fibrosis (recessive allele)
- Describe how gene therapy with viruses can be used to treat cystic fibrosis
- Understand that variation within a species can be genetic, environmental or a combination of both
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Heredity And Genetics. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- An individual with genotype Bb for a gene is described as: A) Homozygous dominant B) Homozygous recessive C) Heterozygous D) Co-dominant Answer: C
- Which genotype gives blood group AB? A) I^A I^A B) I^A i C) I^A I^B D) ii Answer: C
- Polydactyly is caused by which type of allele? A) Recessive B) Dominant C) Co-dominant D) Sex-linked recessive Answer: B
- Why are sex-linked recessive conditions more common in males? A) Males have two X chromosomes B) Males have only one X chromosome, so a recessive allele is not masked C) The Y chromosome carries the recessive allele D) Males cannot be carriers Answer: B
- Gene therapy for cystic fibrosis typically delivers a working gene using: A) A bacterium B) A harmless virus C) A plasmid injected into the blood D) Radiation Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
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