Homozygous means:
Correct answer: D. Having two identical alleles of a gene
- A. Alleles in an organism
- B. Two different alleles of a gene
- C. Having two identical genes
- D. Having two identical alleles of a gene
Explanation
Homozygous refers to a genotype where, for a given trait or gene, the organism possesses two alleles of the same type (i.e. both alleles are dominant or both alleles are recessive). Option D fits this description. Option A merely mentions alleles in an organism, whereas homozygous refers to the allelic combination of a particular trait/gene. Option B refers to the heterozygous state, not homozygous. Option C refers to having two identical genes. Homozygous (and even heterozygous) terms refer to the allelic combination the organism possesses of one particular gene. It is important to remember that an allele is a variant of one particular gene so, one gene may have two or more variants or alleles.
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About Inheritance
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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