Gene Expression and Genetic Variation Test_25.26 - Newcomer International Center | Knihovna

1

During meiosis, what process ensures that each gamete contains only one copy of each gene?

DNA replication

Crossing over

Law of segregation

Fertilization

1

Crossing over during meiosis increases genetic variation by:

Copying genes more than once.

Exchanging segments between homologous chromosomes.

Deleting sections of DNA.

Preventing chromosome separation.

1

A mutation occurs in a sperm cell during DNA replication. What is the most likely result if that sperm fertilizes an egg?

The mutation will be passed to the offspring.

The mutation will be repaired before fertilization.

The mutation will only affect the father.

The mutation will disappear after cell division.

1

Which of the following events create new combinations of alleles in offspring? (Select TWO answers.)

Crossing over during meiosis

DNA replication before mitosis

Random segregation of chromosomes

Chromosome duplication during S phase

1

Why do offspring from the same parents often look different from each other?

Gametes randomly combine different allele combinations.

DNA replication always produces new mutations.

The environment changes the alleles in the parents.

Meiosis creates identical gametes each time.

1

A change from the base sequence GGA to GCA in DNA results in a different amino acid. What type of mutation is this?

Frameshift

Insertion

Deletion

Substitution

1

What is an example of an environmental factor that affects gene expression?

Eating too much sugar deletes sections of DNA.

Smoking adds methyl groups to DNA, which blocks RNA polymerase from binding.

Crossing over during meiosis allows chromosomes to exchange segments of DNA.

Vaping makes it easier for RNA polymerase to bind to DNA, increasing production of proteins.

In chickens, black feathers (F) are dominant and red feathers (f) are recessive.

null

1

If a chicken has the alleles Ff (one allele for black feathers and one allele for red feathers), what will its phenotype be?

Black

Red

1

If a chicken has the alleles ff (two alleles for red feathers), what will its phenotype be?

Black

Red

1

A scientist creates a model showing different allele combinations that could occur during gamete formation. Which concept does this model represent?

Mitosis

Independent assortment

Environmental mutation

Photosynthesis

1

A karyotype reveals three copies of chromosome 21. What process most likely caused this condition?

Fertilization of two sperm cells

Nondisjunction during meiosis

Mutation during replication

Crossing over between chromosomes

1

Why can’t Punnett squares be used to predict chromosomal disorders like Down syndrome?

They only show possible allele combinations, not chromosome number errors.

They do not include dominant or recessive traits.

They only apply to environmental mutations.

They show all possible chromosome arrangements.

1

What happens when a repressor binds to a DNA sequence?

More protein is produced.

The gene turns off.

The gene turns on.

The DNA sequence completely changes.

1

Which best explains why siblings might share some traits but not others?

They inherit random combinations of alleles from their parents.

They always receive identical chromosomes from both parents.

Crossing over ensures all siblings are identical.

Environmental factors erase inherited traits.

1

Why is genetic variation important in a population?

Populations with more genetic variation are more likely to survive.

Populations with more genetic variation cannot adapt to new environmental conditions.

Populations with more genetic variation will take over territory from other populations.

Populations with more genetic variation have more conflict between individuals.