Males have only one *X chromosome*, so if it carries a defective gene, they express the disorder, unlike females, who have another X chromosome that may carry a normal gene.
Related Questions:
- Write the differences between:
- Name sources of variation.
- Give examples of artificial selection.
- What kind of gametes would be produced by organisms having the following genotypes?
- Two white sheep produce a black offspring. What must the parents’ genotype for colour be? What is the probability that the next offspring will be black?
- The diagram shows two varieties of moths in England.
- Among the following genotypes, which ones are heterozygous and which are homozygous? Which of the genotypes have the same phenotype?
- Differentiate between genotype and phenotype.
- What is meant by polygenic inheritance? Give an example.
- How do genes control inheritance of characters?
- Explain the composition of chromatin material.
- Give an account of genes and alleles.
- Describe the role of genes in protein synthesis.
- State and explain Mendel’s law of segregation.
- State and explain Mendel’s law of independent assortment.
- What is co-dominance? Explain with reference to the ABO blood group system.
- Explain incomplete dominance.
- What is co-dominance? Explain with reference to the ABO blood group system.
- What is variation? Explain the sources of variation.
- Explain continuous and discontinuous variation with examples.