Question

Which of the following is not a feature of multifactorial inheritance? a. Effects of dominant alleles are additive. b. Genes affecting the trait may be on multiple chromosomes c. Environment influences phenotype. d. Recessive alleles are harmful.

Short answer

The correct answer is (d) "Recessive alleles are harmful" as it does not align with any features of multifactorial inheritance. In multifactorial inheritance, both dominant and recessive alleles may contribute differently to a trait, and they don't have to be harmful to fit the concept.

Step-by-step solution

Understanding multifactorial inheritance features

Before analyzing the options, it's important to understand the key features of multifactorial inheritance: 1. Multiple genes contribute to the trait. 2. These genes may be on different chromosomes. 3. Both dominant and recessive alleles may play a role. 4. The environment can influence the phenotype. 5. The effects of alleles can be additive or cumulative.

Analyzing the given options

Now, let's analyze each option to determine which one is not a feature of multifactorial inheritance. a. Effects of dominant alleles are additive. This aligns with feature 5 discussed earlier, so this is not the correct answer. b. Genes affecting the trait may be on multiple chromosomes. This aligns with feature 2 discussed earlier, so this is not the correct answer. c. Environment influences phenotype. This aligns with feature 4 discussed earlier, thus this is not the correct answer. d. Recessive alleles are harmful. This statement does not align with any features of multifactorial inheritance. Rarity and harmfulness of recessive alleles is not a defining feature of multifactorial inheritance – both dominant and recessive alleles may contribute differently to a trait, and they don't have to be harmful to fit the concept.

Conclusion

Based on the analysis, option (d) "Recessive alleles are harmful" is not a feature of multifactorial inheritance.

Key concepts

Genetics Education

Genetics education is vital for understanding how our characteristics and susceptibilities to certain diseases are influenced by the genes we inherit from our parents. Central to this field is the concept of multifactorial inheritance, which underlines that most traits result from the interplay of multiple genetic factors rather than a single gene. Importantly, features such as eye color, height, and even the risk for complex diseases like diabetes can be traced back to the combined effects of various genes.

When learning about genetics, it's essential to grasp that genes may reside on any of the chromosomes and can influence traits independently or in conjunction with other genes. Through genetics education, students discover how our vast and diverse genetic makeup interacts with environmental factors to create the unique individuals we are.

Dominant and Recessive Alleles

Alleles are different forms of a gene that determine distinct traits that can be passed from parents to offspring. Understanding the difference between dominant and recessive alleles is critical. A dominant allele is one whose traits are expressed in the individual even if only one copy is present, which means it can mask the effect of a recessive allele paired with it. Conversely, a recessive allele is an allele that must be paired with another recessive allele to exhibit its traits.

However, not all dominant alleles have purely additive effects nor are all recessive alleles harmful, as multifactorial inheritance shows. Traits usually depend on the cumulative effects of many alleles, meaning that a combination of both dominant and recessive alleles is responsible for the resulting phenotype—the observable characteristics of an individual.

Environmental Influence on Phenotype

While genes lay the foundation for the development of an organism, the environment actively interacts with genetics to shape the phenotype. Factors such as nutrition, climate, exposure to toxins, and lifestyle choices can significantly influence how genetic traits are expressed. For example, a person might have the genetic potential to reach a certain height, but this may be altered by the nutrition they receive during growth periods.

In multifactorial inheritance, the environment's role is as critical as the genetic factors. This interplay creates a diverse array of outcomes even when individuals share similar genetic backgrounds. Understanding these nuances in genetic expression helps us appreciate that our traits and health are products of both our genetic blueprints and the environments we live in.