Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What is meant by phenotype in genetics?

1. The specific genes an organism carries

2. The sum of all genetic variations

3. The way traits are expressed in an organism

4. The ratio of dominant to recessive traits

The correct answer is: The way traits are expressed in an organism

Phenotype in genetics refers to the observable characteristics or traits of an organism that result from the interaction of its genotype (the specific set of genes it carries) with the environment. This means that the phenotype encompasses all the physical manifestations of an organism's genetic makeup, such as appearance, behavior, biochemical properties, and physiological functions. The concept of phenotype emphasizes how genetic information is expressed, showcasing that the same genotype can lead to different phenotypes under varying environmental conditions. For example, two plants with the same genetic potential might display different heights due to differences in soil quality, sunlight, or water availability. In contrast, the other options focus on aspects that do not directly define what phenotype is. The specific genes an organism carries refer to its genotype rather than phenotype. The sum of all genetic variations pertains more to genetic diversity and polymorphism rather than individual expression. Lastly, the ratio of dominant to recessive traits relates to Mendelian inheritance patterns and statistical concepts, but does not encapsulate the broader meaning of how traits are physically represented in an organism.