Question

Genes located close together on a chromosome tend to

• A. Show linkage
• B. Assort independently
• C. Mutate frequently
• D. Be recessive

Hint:

Remember Morgan's principle of linkage: \[ \boxed{\text{Closer the genes} \Longrightarrow \text{Stronger the linkage}} \] \[ \boxed{\text{Farther the genes} \Longrightarrow \text{Higher recombination frequency}} \] Linked genes do not follow Mendel's law of independent assortment.

Answer 1

The Correct Option is A

Concept: Genes located on the same chromosome are called linked genes. When two genes are situated very close to each other, they tend to be inherited together because the probability of crossing over occurring between them is very low. This phenomenon is known as linkage.

Step 1: Understand linkage.
Linked genes are physically located on the same chromosome. Since they remain close together, they usually pass from parents to offspring as a single unit. \[ \boxed{\text{Genes Close Together} \longrightarrow \text{Inherited Together}} \]

Step 2: Role of crossing over.
During meiosis, homologous chromosomes exchange segments through crossing over.
• Genes far apart undergo recombination more frequently.
• Genes close together rarely separate because crossing over between them is uncommon. Thus, closely linked genes show strong genetic linkage.

Step 3: Eliminate the incorrect options.

• Independent assortment occurs mainly for genes located on different chromosomes or far apart on the same chromosome.
• Mutation frequency is unrelated to gene proximity.
• Whether a gene is dominant or recessive has no relation to its chromosomal position. Therefore, \[ \boxed{Option (A) is correct \]