2024 Biology Study Guide

Which of the following best describes a gene?

• A segment of DNA that codes for a protein

• A molecule that carries amino acids

• A protein that binds to RNA

• A type of lipid in the cell membrane

Answer explanation

A gene is a segment of DNA that codes for a protein, making the choice 'A segment of DNA that codes for a protein' the best description.

Tags

NGSS.HS-LS1-1

An allele is:

• A physical trait

• A variation of a gene

• A type of chromosome

• A segment of RNA

Answer explanation

An allele is a variation of a gene, not a physical trait, type of chromosome, or segment of RNA.

Tags

NGSS.HS-LS3-2

A genotype refers to:

• The observable characteristics of an organism

• The genetic makeup of an organism

• The environment's influence on an organism

• The number of chromosomes in a cell

Answer explanation

A genotype refers to the genetic makeup of an organism, representing the specific combination of genes in its DNA.

Tags

NGSS.HS-LS3-1

(a)   is an allele that is only expressed when two copies are present.

• An allele that is always expressed
• An allele that is only expressed wh
• An allele that causes dominant trai
• An allele that mutates frequently

Answer explanation

An allele that is only expressed when two copies are present

Homozygous individuals have:

• Two different alleles for a gene

• Two identical alleles for a gene

• A single allele for a gene

• No alleles for a gene

Answer explanation

Homozygous individuals have two identical alleles for a gene, meaning they possess the same version of the gene from both parents.

(a)   is used to predict the outcome of genetic crosses.

• Gel electrophoresis
• Punnett Square
• DNA microarray
• PCR machine

Answer explanation

The Punnett Square is used to predict the outcome of genetic crosses by showing the possible combinations of alleles from the parents.

In Mendelian inheritance, what is the expected phenotypic ratio in the F2 generation of a monohybrid cross?

• 1:1

• 3:1

• 9:3:3:1

• 1:2:1

Answer explanation

In Mendelian inheritance, the expected phenotypic ratio in the F2 generation of a monohybrid cross is 3:1, where 3 represents the dominant phenotype and 1 represents the recessive phenotype.

Incomplete dominance results in:

• A blending of traits

• Only dominant traits being expressed

• Only recessive traits being expressed

• Both alleles being expressed equally

Answer explanation

Incomplete dominance results in a blending of traits where neither allele is completely dominant over the other, leading to an intermediate phenotype.

Codominance occurs when:

• One allele is dominant over the other

• Both alleles contribute to the phenotype

• Alleles blend to form an intermediate trait

• One allele is suppressed

Answer explanation

Codominance occurs when both alleles contribute to the phenotype, showing their effects equally without blending or one being dominant over the other.

Which of the following best describes a phenotype?

• The genetic code of an organism

• The observable traits of an organism

• The sequence of nucleotides in DNA

• The process of transcription

Answer explanation

The observable traits of an organism is the best description of a phenotype as it refers to the physical characteristics resulting from the interaction of an organism's genes with the environment.

Tags

NGSS.HS-LS3-1