TEAS 7 Science Practice Test – Genetics

A gene is best defined as:

A. A structure that carries chromosomes

B. A unit of heredity that codes for a trait

C. The physical appearance of an organism

D. A type of cell division

B. A unit of heredity that codes for a trait

Genes are units of inheritance passed from parents to offspring. 🧠 Memory Trick GENE = GENERATION. Genes pass information from one generation to the next.

An individual with the genotype Aa is:

A. Homozygous dominant

B. Homozygous recessive

C. Heterozygous

D. Codominant

C. Heterozygous

Heterozygous means two different alleles. 🧠 Memory Trick HETERO = Different (Heterogeneous = mixed)

What is the phenotype of an organism?

A. Genetic makeup

B. Chromosome number

C. Observable traits

D. DNA sequence

C. Observable traits

🧠 Memory Trick PHENO = PHOTO. Think of a picture showing visible traits.

According to Mendel's Law of Segregation:

A. Dominant genes disappear

B. Alleles separate during gamete formation

C. Genes mutate during reproduction

D. Chromosomes double

B. Alleles separate during gamete formation

Each gamete receives only one allele. 🧠 Memory Trick SEGREGATION = SEPARATION

A dominant allele:

A. Is always more common

B. Masks a recessive allele

C. Is weaker than recessive

D. Never appears in offspring

B. Masks a recessive allele

One dominant allele is enough to show the trait. 🧠 Memory Trick DOMINANT = BOSS The boss trait gets expressed.

Which genotype is homozygous recessive?

A. AA

B. Aa

C. aa

D. AB

C. aa

Homozygous means same alleles. Recessive uses lowercase letters. 🧠 Memory Trick "aa" = all little letters

A cross between TT and tt produces offspring with which genotype?

A. TT

B. tt

C. Tt

D. 1 TT : 1 tt

C. Tt

Every offspring gets T from one parent and t from the other. 🧠 Memory Trick Pure Tall + Pure Short = All Tt

What is the phenotypic ratio in a monohybrid cross of Tt × Tt?

A. 1:1

B. 2:1

C. 3:1

D. 9:3:3:1

C. 3:1

Three offspring show dominant traits, one shows recessive.

🧠 Memory Trick Mono = 3:1 (Dihybrid = 9:3:3:1)

The Law of Independent Assortment states that:

A. Alleles separate during meiosis

B. Dominant traits always appear

C. Genes assort independently during gamete formation

D. Mutations occur randomly

C. Genes assort independently during gamete formation

Genes for different traits are inherited independently. 🧠 Memory Trick INDEPENDENT = IGNORE EACH OTHER

A dihybrid cross typically produces which phenotypic ratio?

A. 3:1

B. 1:2:1

C. 9:3:3:1

D. 1:1

C. 9:3:3:1

Classic Mendelian dihybrid ratio. 🧠 Memory Trick Two Traits = Four Numbers 9 : 3 : 3 : 1

Which blood type demonstrates codominance?

A. Type O

B. Type A

C. Type B

D. Type AB

D. Type AB

Both IA and IB are expressed equally. 🧠 Memory Trick AB = A AND B Both show up together.

A pink snapdragon flower produced from red and white parents is an example of:

A. Complete dominance

B. Codominance

C. Incomplete dominance

D. Polygenic inheritance

C. Incomplete dominance

The offspring has an intermediate phenotype. 🧠 Memory Trick INCOMPLETE = BLENDING

Which blood type genotype is ii?

A. A

B. B

C. AB

D. O

D. O

Type O occurs only with ii. 🧠 Memory Trick O = "Oh, no dominant alleles!"

Humans determine sex using which chromosome combination?

A. Female = XY, Male = XX

B. Female = XX, Male = XY

C. Female = XO, Male = XX

D. Female = ZZ, Male = ZW

B. Female = XX, Male = XY

Human females are XX and males are XY. 🧠 Memory Trick Y = BOY

Which process can break linkage between genes?

A. Mutation

B. Mitosis

C. Crossing over

D. Fertilization

C. Crossing over

Crossing over exchanges chromosome segments. 🧠 Memory Trick Crossing Over = Chromosome Swap

Genes located on the same chromosome are said to be:

A. Recessive

B. Dominant

C. Linked

D. Polygenic

C. Linked

Linked genes tend to be inherited together. 🧠 Memory Trick Linked = Locked Together

A trait controlled by many genes is called:

A. Codominant

B. Polygenic

C. Recessive

D. Linked

B. Polygenic

Explanation, Examples include height and skin color. 🧠 Memory Trick POLY = MANY

Height in humans is an example of:

A. Discontinuous variation

B. Codominance

C. Continuous variation

D. Mutation

C. Continuous variation

Height occurs across a wide range. 🧠 Memory Trick Continuous = Continues on a spectrum

Which condition is commonly inherited as an X-linked recessive trait?

A. Type AB blood

B. Color blindness

C. Height

D. Eye color

B. Color blindness

Males are affected more often because they have only one X chromosome. 🧠 Memory Trick Color Blindness = X-linked Classic

Which scientist is known as the Father of Genetics?

A. Charles Darwin

B. Louis Pasteur

C. Gregor Mendel

D. Watson

C. Gregor Mendel

Mendel's pea plant experiments established the laws of inheritance. 🧠 Memory Trick Mendel = Mendelian Genetics