Introducing KNOVA — A free reading app with curriculum-aligned passages on History & Science for Grades 3-8Learn More →

What Is a Phenotype? — Reading Comprehension

No ratings yet

Premium Resource

Grades

Standards

MS-LS3-1
MS-LS3-2

Rate this resource

Send Feedback / Report an Issue

About This Reader

This NGSS-aligned reading passage for middle school students introduces the concept of phenotype, which refers to the visible traits or behaviors of an organism. The passage explains the relationship between genotype (genetic makeup) and phenotype (trait expression), emphasizing how both genes and the environment influence how traits appear. Students will learn about multifactorial traits, dominant and recessive allele expression, and how phenotype is used in fields like medicine and agriculture. The passage supports NGSS standard MS-LS3-1 (Heredity: Inheritance and Variation of Traits) and builds science reading comprehension through clear explanations and real-world examples.

CONTENT PREVIEW

A phenotype is the set of physical traits and behaviors that an organism shows. These include things like eye color, height, hair texture, and even how a plant’s leaves look. While a genotype is the set of genes an organism carries, the phenotype is how those genes are expressed in the real world. It’s what you can see or measure.

Phenotypes are influenced by both genetic information and the environment. For example, a person may have genes for tall height, but if they don’t get enough nutrition while growing up, they might not reach their full potential height. This is called a multifactorial trait, where both genes and environment play a role.

Sometimes, different genotypes can produce the same phenotype. A person with a BB genotype and a person with a Bb genotype will both show the dominant trait—for example, brown eyes. The recessive trait, like blue eyes, only shows up when someone has a bb genotype. This is why understanding both genotype and phenotype is important when studying heredity.

Scientists use phenotype observations in many areas. In medicine, a patient’s phenotype—such as symptoms or traits—helps diagnose genetic conditions. In farming, farmers choose plants with the best phenotypes (like the juiciest fruit or tallest stalks) to grow in future seasons.

Phenotypes give us the visible clues to how our genes work and how the environment can shape who we are. By studying them, scientists can better understand inheritance, variation, and evolution.

Fun Fact: Identical twins have the same genotype, but their phenotypes can still be different—especially as they grow up in different environments!

What is a phenotype?

A group of cellsThe genes inside an organismThe visible traits of an organismThe nutrients in food

Which of the following is an example of a phenotype?

Having the Bb genotypeBrown eyesA dominant alleleA gene mutation

What influences a phenotype?

Only genesOnly foodBoth genes and environmentThe weather

What does it mean if a trait is multifactorial?

It is shared by twinsIt’s caused by many genesIt is affected by genes and environmentIt cannot be inherited

Why might two people with different genotypes look the same?

They both have blue eyesThey have the same phenotypeTheir DNA is missingThey are not human

What is one way scientists use phenotype in real life?

To change genotypesTo create new DNATo diagnose genetic conditionsTo stop evolution

What is the main idea of the passage?

Phenotype shows how genes and environment affect traitsGenotypes and phenotypes are the sameOnly recessive traits are inheritedBrown eyes are the most common trait

How do farmers use phenotype?

To avoid planting cropsTo find hidden genesTo select the best traits in plantsTo measure root length only