Comprehensive Biology Quiz-Style Questions (Ch. 8, 9, 10, 12 + Cell Signaling)

What checkpoint ensures all chromosomes are properly attached to the spindle before anaphase begins?

M checkpoint

The formation of gametes occurs through __________.

meiosis

True or False: Crossing over occurs during Metaphase I of meiosis.

False, crossing over occurs during Prophase I of meiosis.

G1 phase

Cell grows and performs normal functions

S phase

DNA is replicated

G2 phase

Cell prepares for division

M phase

Mitosis and cytokinesis occur

What is the ploidy of daughter cells produced by mitosis?

Diploid (2n)

What is nondisjunction?

Failure of chromosomes to separate properly during meiosis

Which life cycle is seen in fungi where only the zygote is diploid?

Haploid-dominant

Genetic variation is introduced during meiosis through independent assortment and __________.

crossing over

 What are the four nitrogenous bases in DNA?

Adenine, Thymine, Guanine, Cytosine

The enzyme __________ proofreads new DNA strands and replaces incorrect nucleotides.

DNA polymerase

True or False: DNA replication is unidirectional.

False, DNA replication is bidirectional, creating a replication bubble.

Topoisomerase

Relieves torsional strain

Helicase

Unwinds the helix

DNA ligase

Seals Okazaki fragments

Primase

Lays down RNA primer

What molecule acts as a template for RNA during transcription?

DNA

The promoter sequence for transcription in eukaryotes often includes the __________ box

TATA

True or False: Introns are expressed sequences in mRNA

False, introns are non-coding sequences that are removed during mRNA processing.

What happens at the A site of a ribosome?

A tRNA with its amino acid enters and pairs with the mRNA codon

Transcription

is the process by which RNA is synthesized from a DNA template, resulting in the formation of messenger RNA (mRNA) that carries genetic information for protein synthesis.

RNA splicing

is the process of removing introns from pre-mRNA and joining exons together to form mature mRNA.

Translation

is the process by which ribosomes synthesize proteins using the mRNA sequence as a template to assemble amino acids in the correct order.

Protein folding

Yields functional protein

What type of mutation changes a codon to a stop codon?

Nonsense mutation

What disease is caused by a single point mutation in the hemoglobin gene?

Sickle-cell disease

A __________ mutation does not alter the amino acid sequence.

silent

Mendel’s Law of Segregation refers to what?

Alleles separate during gamete formation

What is the phenotype ratio of a monohybrid cross?

3:1

True or False: X-linked traits are passed equally by both sexes.

False, they are passed differently between sexes.

What is polygenic inheritance?

Trait controlled by multiple genes with additive effects

An individual with one recessive allele but no symptoms is a __________.

carrier of the trait

What is codominance?

Both alleles are fully expressed in the heterozygote

What makes a gene pleiotropic?

It affects multiple traits

True or False: Genes that are close together on the same chromosome always assort independently.

False, they tend to be inherited together.

Codominance

A genetic scenario where both alleles are expressed equally in the phenotype of a heterozygote. ex. AB blood type

Incomplete dominance

occurs when the phenotype is a blend of both alleles, such as pink flowers from red and white parents.

Polygenic

inheritance where multiple genes influence a trait, resulting in continuous variation, such as height or skin color.

Pleiotropy

Marfan syndrome

What type of cell signaling occurs when a cell targets itself?

Autocrine signaling

A __________ binds a receptor to trigger a response.

ligand

What is the purpose of a signal transduction pathway?

To convert a signal from outside the cell into a functional response inside the cell.

Endocrine

Long distance

Paracrine

Short distance signaling between cells.

Autocrine

Cell signaling where a cell targets itself.

Direct contact

Cell signaling that occurs when cells are physically touching, allowing for communication through molecules or junctions.

What are second messengers?

Small molecules that amplify the signal inside the cell

True or False: Every cell expresses the same receptors for all ligands

False, different cell types express different receptors.

What is the correct sequence described by the central dogma of molecular biology?

DNA → RNA → Protein

The process of converting DNA into RNA is called __________.

transcription.

The process of using an RNA transcript to build a protein is called __________.

translation.

True or False:
In eukaryotes, transcription and translation occur in the same cellular compartment.

False; in eukaryotes, transcription occurs in the nucleus and translation occurs in the cytoplasm.

DNA →

stores genetic information

mRNA →

carries the genetic code from nucleus to cytoplasm

Ribosome →

reads mRNA and assembles amino acids

tRNA →

brings amino acids to the ribosome

What enzyme is responsible for transcribing DNA into RNA?

RNA polymerase

What occurs directly because of the central dogma?

Genes are translated into proteins

What is a component of a DNA nucleotide?

Deoxyribose, phosphate, thymine

The two strands of a DNA double helix are held together by __________ bonds between complementary bases.

hydrogen

True or False:
Adenine always pairs with cytosine in DNA.

False; adenine pairs with thymine.

What does it mean that DNA strands are antiparallel?

One strand runs 5′ to 3′, the other runs 3′ to 5′

Helicase →

an enzyme that unwinds the DNA double helix during replication.

DNA polymerase III →

extends the new DNA strand

During replication, the strand synthesized continuously is called the __________ strand.

leading

What is the role of topoisomerase in DNA replication?

Relieves tension ahead of the replication fork by making temporary cuts in the DNA strands to prevent supercoiling.

True or False:
Eukaryotic chromosomes replicate from a single origin of replication.

False, they replicate from multiple origins of replication.

Adenine (A) →

Thymine

Uracil (U) →

Adenine

Cytosine (C) →

Guanine

Guanine (G) →

Cytosine