Heredity And Mendel's First Law
Overview
Why does a black bull crossed with a black cow sometimes throw a red calf. Why do two hornless goats occasionally produce a horned kid. The answer is not chance: it is heredity, the orderly passing of traits from parent to offspring, and it follows rules precise enough to predict on paper before a single mating takes place.
In this lesson you will learn the vocabulary breeders and examiners share: gene, allele, dominant, recessive, genotype and phenotype. You will then meet Mendel's first law, the law of segregation, and use it to solve monohybrid cross problems on real farm traits, coat colour and the polled condition, working out exactly what a planned mating is likely to produce.
Objectives
- Define heredity
- State Mendel's first law of inheritance
- Explain the terms gene, allele, dominant and recessive
- Solve a simple monohybrid cross problem using Mendel's first law
- Explain the application of Mendel's first law to animal breeding
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Heredity And Mendel's First Law. 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.
- In cattle, black coat colour (B) is dominant over red coat colour (b). What is the phenotype of an animal with genotype Bb? A. Red B. Black C. A mixture of red and black D. Cannot be determined Answer: B
- The actual pair of alleles an animal carries for a gene is called its: A. Phenotype B. Genotype C. Allele D. Chromosome Answer: B
- Mendel's first law states that: A. Genes for different traits assort independently B. The two alleles of a gene separate during gamete formation C. Dominant alleles always outnumber recessive alleles D. Offspring always resemble one parent exactly Answer: B
- Two heterozygous polled goats (Pp) are mated. What phenotype ratio is expected among the offspring? A. 1 polled : 1 horned B. 1 polled : 3 horned C. 3 polled : 1 horned D. All polled Answer: C
- An animal carrying two identical alleles for a gene, such as BB, is described as: A. Heterozygous B. Homozygous C. Recessive D. Hybrid Answer: B
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