Which of the following best describes the law of independent assortment?
A. There are dominant and recessive genes
B. There are two genes that control inheritance.
C. Two genes of the same characteristic separate into different gametes.
D. Genes controlling different characteristics are inherited independently of each other.
The Correct Answer and Explanation is :
Correct Answer:
D. Genes controlling different characteristics are inherited independently of each other.
Explanation:
The law of independent assortment is one of Gregor Mendel’s fundamental principles of genetics, derived from his experiments with pea plants. This law states that genes for different traits are inherited independently of one another, provided the genes are located on different chromosomes or far apart on the same chromosome.
Key Points:
- Independent Inheritance: The principle means that the inheritance of one trait (e.g., seed color) does not influence the inheritance of another trait (e.g., seed shape). For instance, a plant inheriting a gene for yellow seeds has no effect on whether it inherits a gene for round seeds.
- Mechanism: This phenomenon occurs during meiosis, the process that produces gametes (sperm and egg cells). Homologous chromosomes carrying different gene pairs align and segregate independently into gametes. This creates diverse combinations of alleles.
- Genetic Variation: The law of independent assortment contributes significantly to genetic variation, as it allows for numerous combinations of traits in offspring. For example, if two traits are governed by two gene pairs (Aa and Bb), four combinations of gametes (AB, Ab, aB, ab) can be produced, leading to a variety of genetic outcomes.
- Exceptions: This law applies only when genes are unlinked, meaning they are on different chromosomes or far apart on the same chromosome. Genes that are closely linked on the same chromosome tend to be inherited together unless crossing over occurs during meiosis.
Historical Context:
Mendel discovered this law by observing patterns in dihybrid crosses, where he examined two traits simultaneously. He noticed that the ratios of offspring were consistent with independent assortment, not influenced by one another.
In summary, the law of independent assortment is crucial for understanding how diverse genetic combinations arise, explaining how traits are passed from parents to offspring.