1. Dihybrid cross is matched with: the breeding of two organisms that have genes for two different characteristics.
The dihybrid cross is a cross used to study the inheritance of two traits or two pairs of alleles. Parents have different pairs of alleles for each trait considered. One parent has a homozygous dominant allele for one trait while the other parent has the homozygous recessive allele for that particular trait. When a cross is made between two parents above, all in the F1 generation will be the same. Then, the F1 generation is selfed, and the resulting F2 generation will have a phenotypic ratio of 9: 3: 3: 1 and a genotype ratio of 1: 2: 1: 2: 4: 2: 1: 2: 1.
2. Replication is matched with: separation of DNA's two polynucleotide chains, which act as a template for a new chain.
Replication is the mechanism of production of new nucleic molecules of DNA (or RNA in the case of certain viruses). At the cellular level, the copy of the DNA results in the formation of two daughter molecules identical to each other and to the parent molecule. This phenomenon occurs at the level of chromosomes, before cell division (chromosomal replication).
3. Multiple alleles is matched with: when more than two alternatives for a gene exist.
Most genes have more than two alleles. This phenomenon is called multiple alleles. An example of multiple alleles is blood groups. There are four blood groups represented by the A, B and O alleles (the blood groups are: A, B, O and AB).
The four blood groups are represented by different combinations of three alleles designated by IA (for A), IB (for B) and i (for neither A nor B). There are six possible genotypes. Each person has two alleles among the three possible ones (A, B and O).
4. Mutation is matched with: a copying mistake made during DNA replication.
A genetic mutation is a modification of the DNA sequence of a gene. This results in erroneous information in the manufacture of proteins. As a result, the proteins are absent, deficient or insufficient.
The causes of genetic mutations are generally poorly understood. Genetic mutations can be caused by environmental factors, such as air pollution or radiation, but can also occur spontaneously from one generation to the next without apparent cause.
5. Codominance is matched with: when both genes are dominant and both are expressed in the phenotype.
In genetics, codominance refers to the fact that two different variants of a gene, called alleles, participate in common in the determination of a particular trait, called phenotype, such as the color of the epidermis or coat. More precisely, in an individual who carries two different alleles of a gene (heterozygous genotype), both express themselves at the same time to generate an intermediate phenotype between those which would have been obtained if the two alleles had been identical (homozygous genotype).