Color blindness is an inherited vision defect that primarily affects which group of people?

Introduction / Context:
Color blindness refers to difficulties in distinguishing certain colors, most commonly red and green. It is usually an inherited condition caused by defects in cone cells in the retina. This question asks which group is primarily affected, based on the genetics of common types of color blindness.

Given Data / Assumptions:

• The defect referred to is typical red green color blindness.
• The inheritance pattern is X linked recessive, which is standard for this condition.
• The options compare males, females, and children generally.

Concept / Approach:
Most common forms of color blindness are inherited as X linked recessive traits. Males have one X and one Y chromosome, while females have two X chromosomes. A male with a defective allele on his single X chromosome will express the trait, because there is no second normal copy to mask it. A female would need two defective alleles, one on each X, to express the condition, which is less likely statistically. Therefore, color blindness occurs much more often in males than in females.

Step-by-Step Solution:
Step 1: Consider option A. It suggests that children of both sexes are equally affected, which would be true for autosomal traits but not for X linked recessive ones.Step 2: Consider option B. It states that males are affected much more frequently than females. This matches the expected pattern for X linked recessive inheritance in human populations.Step 3: Consider option C. It claims females are much more frequently affected, which contradicts established epidemiological data.Step 4: Consider option D. It suggests equal frequency in males and females, which again is not true for X linked recessive traits.Step 5: Conclude that option B is correct.

Verification / Alternative check:
As an alternative check, recall typical prevalence numbers: in many populations, about 8 percent of males and less than 1 percent of females have some form of red green color blindness. This large difference reflects the underlying X linked recessive inheritance and confirms that males are more commonly affected.

Why Other Options Are Wrong:
Option A is wrong because it ignores the role of sex chromosomes and treats the condition as if it were autosomal. Option C is wrong because it reverses the known pattern, claiming females are mostly affected. Option D is wrong because equal frequencies would not be expected given the different numbers of X chromosomes in males and females.

Common Pitfalls:
Students may forget that some traits are sex linked and automatically assume equal distribution between males and females. Another pitfall is failing to connect the idea of an X linked gene with different probabilities for each sex. To avoid this, remember that X linked recessive traits, like typical red green color blindness and hemophilia, occur predominantly in males.

Final Answer:
Males much more frequently than females.