Luke L. answered • 02/21/20
Recent MD graduate! Friendly, professional, and methodical.
The correct answer is 2 - "Traits are influenced by both genes and the environment".
1. A dominant trait is most likely to occur.
This is FALSE. While this may seem true at face value (dominant traits win, right?), it boils down to how common these traits are in the population. Some dominant traits, such as Huntington disease or polycystic kidney disease, are less common than the recessive trait (= not having the disease).
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2. Traits are influenced by both genes and the environment.
This is TRUE. Genes determine traits, but the environment can contribute (in varying degrees). Your eye color is determined by genes and not much can change it. However, height has a strong genetic component and plenty of things change that (sleep, malnutrition, growth hormone).
3. Genes determine all traits.
This is FALSE. This is too broad and absolute to be correct. We haven't mapped out our genome well enough to prove this reliably. Plus, I don't think fear of heights is a trait entirely determined by genes. Additionally, it contradicts choice #2 - meaning, depending on the style of test you're taking, one of these two must be correct and the other incorrect.
In solving questions like this, it's important to keep your definitions straight - as problems will frequently try to confuse you with terminology.
Trait - One characteristic of an organism (e.g. widow's peak, flower color). This is similar to phenotype, which is the sum of all characteristics.
Allele - This is the genetic component that determines what an organism's trait will be. It can be dominant or recessive (or one of the many other options including codominance, covered in your textbooks).
Please let me know if this was helpful!
Kind regards,
Luke
