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Biology_Set_8(1)

Question 1 of 35

During which mitotic stage do chromosomes first become visibly condensed?

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Biology_Set_8(1) Practice Questions

Review these Biology_Set_8(1) nursing practice questions with answer choices and explanations.

Question 1

During which mitotic stage do chromosomes first become visibly condensed?

  1. Telophase
  2. Anaphase
  3. Prophase
  4. Metaphase
View answer and explanation

Correct answer:

  1. Prophase

Explanation: Chromatin condenses into visible chromosomes as prophase begins.

Question 2

During which stage do new nuclear envelopes usually form around separated chromosome sets?

  1. Metaphase
  2. Telophase
  3. S phase
  4. Anaphase
View answer and explanation

Correct answer:

  1. Telophase

Explanation: Telophase reestablishes nuclei around the chromosome sets at opposite poles.

Question 3

What forms between daughter nuclei during cytokinesis in a plant cell?

  1. A spindle checkpoint
  2. A flagellum
  3. A cleavage furrow only
  4. A cell plate
View answer and explanation

Correct answer:

  1. A cell plate

Explanation: Vesicles form a cell plate that develops into the partition between daughter cells.

Question 4

What forms during cytokinesis in a typical animal cell?

  1. A cleavage furrow
  2. A cellulose wall
  3. A chloroplast
  4. A pollen tube
View answer and explanation

Correct answer:

  1. A cleavage furrow

Explanation: A contractile ring draws the membrane inward, producing a cleavage furrow.

Question 5

What is the main role of spindle fibers during cell division?

  1. Producing antibodies
  2. Building cell walls
  3. Digesting glucose
  4. Moving and separating chromosomes
View answer and explanation

Correct answer:

  1. Moving and separating chromosomes

Explanation: Spindle microtubules position chromosomes and help separate them.

Question 6

What is the centromere region of a duplicated chromosome associated with?

  1. Synthesis of cellulose
  2. Attachment of sister chromatids and formation of kinetochores
  3. Formation of chloroplasts
  4. Production of bile
View answer and explanation

Correct answer:

  1. Attachment of sister chromatids and formation of kinetochores

Explanation: The centromere region helps maintain chromatid association and supports the chromosome's spindle-attachment structures.

Question 7

A diploid cell has 12 chromosomes. How many chromosomes should each normal gamete contain?

  1. 12
  2. 6
  3. 3
  4. 24
View answer and explanation

Correct answer:

  1. 6

Explanation: Meiosis halves the diploid chromosome number, so each gamete has six.

Question 8

What separates during anaphase I of meiosis?

  1. Sister chromatids in every chromosome
  2. Amino acids
  3. RNA codons
  4. Homologous chromosomes
View answer and explanation

Correct answer:

  1. Homologous chromosomes

Explanation: Homologous chromosomes move apart while sister chromatids generally remain together.

Question 9

What separates during anaphase II of meiosis?

  1. Sister chromatids
  2. Paired organs
  3. Homologous chromosome pairs without chromatid separation
  4. Phospholipid heads
View answer and explanation

Correct answer:

  1. Sister chromatids

Explanation: Meiosis II separates sister chromatids, much like mitotic anaphase.

Question 10

What is independent assortment during meiosis?

  1. Copying only dominant alleles
  2. Removal of all recessive alleles
  3. Random orientation of homologous chromosome pairs that affects their distribution to gametes
  4. Fusion of gametes
View answer and explanation

Correct answer:

  1. Random orientation of homologous chromosome pairs that affects their distribution to gametes

Explanation: Different chromosome pairs orient independently, generating different combinations in gametes.

Question 11

Which term describes genes located close together on the same chromosome that tend to be inherited together?

  1. Linked genes
  2. Identical genes
  3. Deleted genes
  4. Recessive genes only
View answer and explanation

Correct answer:

  1. Linked genes

Explanation: Nearby genes are less likely to be separated by crossing over.

Question 12

What is a carrier of an autosomal recessive condition?

  1. Any person with no copy of the allele
  2. A person lacking all chromosomes
  3. Only an affected homozygous person
  4. A heterozygous individual who usually does not show the condition
View answer and explanation

Correct answer:

  1. A heterozygous individual who usually does not show the condition

Explanation: Carriers possess one recessive condition-associated allele and one functional allele in the simple model.

Question 13

Two carriers have genotypes Aa and Aa for an autosomal recessive condition. What is the probability of an unaffected child?

  1. 50%
  2. 100%
  3. 75%
  4. 25%
View answer and explanation

Correct answer:

  1. 75%

Explanation: AA and Aa are unaffected in this model, representing three of four expected combinations.

Question 14

A parent with genotype AA is crossed with a parent with genotype aa. What genotype is expected in all offspring?

  1. A only
  2. AA
  3. aa
  4. Aa
View answer and explanation

Correct answer:

  1. Aa

Explanation: Every offspring receives A from one parent and a from the other.

Question 15

An Aa individual is crossed with an AA individual. What percentage of offspring is expected to be homozygous dominant?

  1. 100%
  2. 0%
  3. 25%
  4. 50%
View answer and explanation

Correct answer:

  1. 50%

Explanation: The cross produces AA and Aa in equal expected proportions.

Question 16

Why are typical XY males more likely than XX females to express some X-linked recessive conditions?

  1. They usually have only one copy of most X-linked genes
  2. All Y genes are dominant
  3. They inherit two X chromosomes
  4. Their X chromosome contains no genes
View answer and explanation

Correct answer:

  1. They usually have only one copy of most X-linked genes

Explanation: A recessive allele on their single X often lacks a corresponding second X allele to mask its effect.

Question 17

What does a pedigree chart show?

  1. The order of amino acids in a protein
  2. The stages of digestion
  3. Inheritance of a trait across family generations
  4. The parts of a microscope
View answer and explanation

Correct answer:

  1. Inheritance of a trait across family generations

Explanation: Pedigrees track affected and unaffected relatives to help identify inheritance patterns.

Question 18

What is a karyotype?

  1. A sequence of amino acids
  2. An organized display of chromosomes
  3. A list of enzymes
  4. A diagram of organelles
View answer and explanation

Correct answer:

  1. An organized display of chromosomes

Explanation: Karyotypes arrange chromosomes by features such as size and shape.

Question 19

What is trisomy?

  1. The presence of three copies of a particular chromosome
  2. The absence of all chromosomes
  3. A chromosome with three centromeres
  4. Three copies of every gene in all cases
View answer and explanation

Correct answer:

  1. The presence of three copies of a particular chromosome

Explanation: Trisomy means a specific chromosome is present in three copies instead of the usual two.

Question 20

Which enzyme separates DNA strands at the replication fork?

  1. Pepsin
  2. ATP synthase
  3. Amylase
  4. Helicase
View answer and explanation

Correct answer:

  1. Helicase

Explanation: Helicase unwinds the double helix so each strand can be copied.

Question 21

Which enzyme joins DNA fragments by sealing breaks in the sugar-phosphate backbone?

  1. Catalase
  2. DNA ligase
  3. Lipase
  4. RNA polymerase
View answer and explanation

Correct answer:

  1. DNA ligase

Explanation: DNA ligase seals backbone breaks, including between fragments on the lagging strand.

Question 22

What are Okazaki fragments?

  1. Segments removed from a chromosome during mitosis
  2. Parts of a cell wall
  3. Short DNA segments made on the lagging strand
  4. Pieces of digested protein
View answer and explanation

Correct answer:

  1. Short DNA segments made on the lagging strand

Explanation: The lagging strand is synthesized in short fragments that are later joined.

Question 23

Which enzyme makes RNA from a DNA template?

  1. Protease
  2. DNA ligase
  3. RNA polymerase
  4. Helicase only
View answer and explanation

Correct answer:

  1. RNA polymerase

Explanation: RNA polymerase assembles complementary RNA nucleotides during transcription.

Question 24

What is a promoter in gene expression?

  1. A lipid that stores energy
  2. A chromosome-separating organelle
  3. A DNA region where transcription machinery assembles
  4. A protein that digests RNA
View answer and explanation

Correct answer:

  1. A DNA region where transcription machinery assembles

Explanation: Promoters help specify where transcription begins.

Question 25

Which sequences are usually removed from a eukaryotic pre-mRNA during splicing?

  1. Introns
  2. All codons
  3. All nucleotides
  4. Exons
View answer and explanation

Correct answer:

  1. Introns

Explanation: Splicing removes introns and joins the retained exons.

Question 26

What does a stop codon signal?

  1. Beginning of DNA replication
  2. Pairing of homologous chromosomes
  3. Termination of translation
  4. Formation of a lipid bilayer
View answer and explanation

Correct answer:

  1. Termination of translation

Explanation: Stop codons direct the translation machinery to end the growing polypeptide.

Question 27

What is an anticodon?

  1. A three-base sequence on tRNA that pairs with an mRNA codon
  2. A whole chromosome
  3. A sugar in DNA
  4. An enzyme that removes proteins
View answer and explanation

Correct answer:

  1. A three-base sequence on tRNA that pairs with an mRNA codon

Explanation: The anticodon helps match a tRNA's amino acid with the appropriate codon.

Question 28

Which change is most likely to cause a frameshift in a coding sequence?

  1. A change outside the coding sequence only
  2. Insertion of one nucleotide
  3. Insertion of three nucleotides
  4. Replacement of one nucleotide without insertion
View answer and explanation

Correct answer:

  1. Insertion of one nucleotide

Explanation: A one-base insertion shifts the grouping of downstream codons.

Question 29

What is a silent mutation?

  1. A mutation occurring only at night
  2. A mutation that removes every gene
  3. Any mutation that stops transcription
  4. A DNA change that does not alter the encoded amino acid
View answer and explanation

Correct answer:

  1. A DNA change that does not alter the encoded amino acid

Explanation: Different codons can specify the same amino acid, so some substitutions leave the protein sequence unchanged.

Question 30

What is a nonsense mutation?

  1. A mutation that changes an amino-acid codon into a stop codon
  2. A duplication of the whole nucleus
  3. A change that always improves a protein
  4. A mutation with no DNA change
View answer and explanation

Correct answer:

  1. A mutation that changes an amino-acid codon into a stop codon

Explanation: A premature stop codon can produce a shortened protein.

Question 31

What is a polygenic trait?

  1. A trait caused by one chromosome disappearing
  2. A trait determined by no genes
  3. A trait influenced by multiple genes
  4. A trait found only in bacteria
View answer and explanation

Correct answer:

  1. A trait influenced by multiple genes

Explanation: Many traits, including human height, are influenced by numerous genes.

Question 32

Which example best illustrates environmental influence on phenotype?

  1. An egg becomes diploid without fertilization
  2. Genetically similar plants grow to different heights under different light conditions
  3. A DNA base always pairs randomly
  4. A chromosome loses every gene
View answer and explanation

Correct answer:

  1. Genetically similar plants grow to different heights under different light conditions

Explanation: Environmental conditions can alter trait expression even when genetic backgrounds are similar.

Question 33

Which mutation could be inherited by a child?

  1. A mutation only in a parent's muscle cell
  2. A mutation present in a sperm or egg involved in fertilization
  3. A mutation only in a parent's liver cell
  4. A mutation only in a parent's skin cell
View answer and explanation

Correct answer:

  1. A mutation present in a sperm or egg involved in fertilization

Explanation: Gametes transmit DNA to offspring; most somatic-cell mutations are not inherited.

Question 34

What is the main result of uncontrolled cell-cycle progression?

  1. Excessive cell division that can contribute to cancer
  2. Permanent elimination of mutations
  3. Guaranteed production of normal gametes
  4. Automatic formation of chloroplasts
View answer and explanation

Correct answer:

  1. Excessive cell division that can contribute to cancer

Explanation: Failure of division controls can allow abnormal cells to multiply.

Question 35

An RNA sequence contains 18 coding bases with no stop codon in that segment. How many amino acids can the segment specify?

  1. 3
  2. 6
  3. 9
  4. 18
View answer and explanation

Correct answer:

  1. 6

Explanation: Each amino acid is specified by a three-base codon, so 18 divided by 3 equals six.