(PRELIM) Cytogenetics - AUGUST 18, 2025

A

What is a chromosome?

a) A threadlike structure in the nucleus made of DNA coiled around proteins

b) A long, thin, uncoiled thread of DNA called chromatin

c) A protein that codes for a specific trait

d) A segment of DNA that codes for a specific protein

A

What is the basic monomer, or building block, of DNA?

a) Nucleotide

b) Protein

c) Chromosome

d) Gene

A

A DNA nucleotide is composed of which three components?

a) A phosphate group, a deoxyribose sugar, and a nitrogenous base

b) A pentose sugar, a nitrogenous base, and an amino acid

c) A phosphate group, a ribose sugar, and a nitrogenous base

d) A sugar-phosphate backbone and a nitrogenous base

A

What is the name of the sugar found in a DNA nucleotide?

a) Deoxyribose

b) Ribose

c) Glucose

d) Fructose

A

Which of the following is NOT one of the nitrogenous bases found in DNA?

a) Uracil

b) Cytosine

c) Adenine

d) Guanine

A

According to Chargaff's rule, which base pairs with Adenine (A) in a DNA molecule?

a) Thymine (T)

b) Guanine (G)

c) Uracil (U)

d) Cytosine (C)

A

According to Chargaff's rule, which base pairs with Guanine (G) in a DNA molecule?

a) Cytosine (C)

b) Adenine (A)

c) Thymine (T)

d) Uracil (U)

A

The double helix structure of DNA is often compared to a twisted ladder. What forms the "rungs" of this ladder?

a) The nitrogenous base pairs

b) The deoxyribose sugars

c) The sugar-phosphate backbone

d) The phosphate groups

A

What is the term for a segment of DNA that codes for a specific protein or trait?

a) Gene

b) Chromosome

c) Nucleotide

d) Allele

A

What is an allele?

a) A different version of the same gene

b) A segment of DNA

c) The whole packaged structure of DNA and proteins

d) A chromosome that is not a sex chromosome

A

What is the term for the genetic makeup of an organism, which may not always be visible?

a) Genotype

b) Allele

c) Phenotype

d) Chromosome

A

What is the term for the observable traits or characteristics of an organism?

a) Phenotype

b) Allele

c) Genotype

d) Chromosome

A

What is the name of the process where cells with damaged DNA are detected and undergo programmed cell death to prevent harm?

a) Apoptosis

b) Mitosis

c) Replication

d) Meiosis

A

What is the term for the loose, thread-like form of DNA that exists when a cell is not dividing?

a) Chromatin

b) Chromatid

c) Chromosome

d) Centromere

A

What is the term for the condensed, tightly packed DNA that becomes visible during cell division?

a) Chromosome

b) Gene

c) Chromatid

d) Chromatin

A

What is the constricted region of a chromosome that holds sister chromatids together and divides the chromosome into arms?

a) Centromere

b) Telomere

c) Kinetochore

d) Nucleosome

A

What is the name of the specialized protein structure formed at the centromere to which spindle fibers attach during cell division?

a) Kinetochore

b) Telomere

c) Nucleolus

d) Histone

A

What are the repetitive sequences found at the ends of chromosomes that protect them from damage and fusion?

a) Telomeres

b) Centromeres

c) Kinetochores

d) Nucleolar Organizer Regions (NORs)

A

What is the name for the shorter arm of a chromosome?

a) p arm

b) q arm

c) h arm

d) s arm

A

What is the name for the longer arm of a chromosome?

a) q arm

b) p arm

c) h arm

d) l arm

D

A chromosome with its centromere located in the middle, resulting in arms of equal length, is called:

a) Acrocentric

b) Submetacentric

c) Telocentric

d) Metacentric

D

A chromosome with its centromere located slightly off-center, with one arm shorter than the other, is called:

a) Acrocentric

b) Metacentric

c) Telocentric

d) Submetacentric

D

A chromosome with its centromere located very close to one end, producing a very short p arm and a long q arm, is called:

a) Submetacentric

b) Metacentric

c) Telocentric

d) Acrocentric

D

A chromosome with its centromere located at the very end, with only one visible arm, is called:

a) Acrocentric

b) Metacentric

c) Submetacentric

d) Telocentric

D

What is the term for the more condensed, tightly packed form of chromatin that is transcriptionally inactive and stains darker?

a) Euchromatin

b) Solenoid

c) Nucleosome

d) Heterochromatin

D

What is the term for the less condensed, loosely packed form of chromatin that is transcriptionally active and stains lighter?

a) Solenoid

b) Heterochromatin

c) Nucleosome

d) Euchromatin

D

What is the name of the proteins around which DNA tightly coils to form chromatin?

a) Ribosomes

b) Enzymes

c) Antigens

d) Histones

D

What are the bead-like structures formed when DNA wraps around histone proteins?

a) Telomeres

b) Kinetochores

c) Solenoids

d) Nucleosomes

D

What is the name of the enzyme that extends telomeres, allowing cells to divide indefinitely?

a) Helicase

b) DNA polymerase

c) Ligase

d) Telomerase

D

In DNA replication, what is the name of the enzyme that "unzips" the DNA double helix by breaking the hydrogen bonds between base pairs?

a) DNA polymerase

b) Primase

c) DNA ligase

d) Helicase

D

In DNA replication, what is the enzyme that adds complementary nucleotides in the 5' to 3' direction?

a) Helicase

b) Primase

c) DNA ligase

d) DNA polymerase

D

In DNA replication, what is the enzyme that seals any gaps, completing the sugar-phosphate backbone?

a) Helicase

b) Primase

c) DNA polymerase

d) DNA ligase

D

What is the name for the DNA that is found in the mitochondria and is passed down only from the mother?

a) Nuclear DNA

b) Autosomal DNA

c) Chloroplast DNA

d) Mitochondrial DNA

D

What is the name for the DNA found in the nucleus that is responsible for an individual's unique genetic identity and is inherited from both parents?

a) Autosomal DNA

b) Mitochondrial DNA

c) Chloroplast DNA

d) Nuclear DNA

D

How many pairs of autosomes do humans have?

a) 1 pair

b) 46 pairs

c) 23 pairs

d) 22 pairs

D

How many pairs of sex chromosomes do humans have?

a) 46 pairs

b) 22 pairs

c) 23 pairs

d) 1 pair

D

What is the term for the process of exchanging genetic material between homologous chromosomes, which leads to genetic variation?

a) Mitosis

b) DNA replication

c) Apoptosis

d) Crossing over

D

In the context of the cell cycle, during which phase does DNA synthesis (replication) occur?

a) G1 phase

b) M phase

c) G2 phase

d) S phase

D

What is the term for the specific paragraphs of a DNA "book" that give instructions for a particular trait?

a) Chromosomes

b) Nucleotides

c) Alleles

d) Genes

D

What is a polymer?

a) A small unit that makes up a larger molecule

b) A protein that regulates gene expression

c) A single strand of DNA

d) A large molecule made of repeating units

A

What is the monomer of a polymer?

a) The smaller unit that makes up the polymer

b) The large molecule itself

c) A segment of the polymer

d) A different version of the polymer

B

How many hydrogen bonds hold an Adenine (A) and Thymine (T) base pair together?

a) 1

b) 2

c) 3

d) 4

C

How many hydrogen bonds hold a Guanine (G) and Cytosine (C) base pair together?

a) 1

b) 2

c) 3

d) 4

C

Which of the following is a purine base?

a) Cytosine (C)

b) Thymine (T)

c) Adenine (A)

d) Uracil (U)

C

Which of the following is a pyrimidine base?

a) Adenine (A)

b) Guanine (G)

c) Cytosine (C)

d) A and G

B

What is the direction of DNA replication and transcription?

a) 3' to 5'

b) 5' to 3'

c) Both directions simultaneously

d) From the centromere outward

B

In the antiparallel structure of DNA, one strand runs 5'→3'. How does the other strand run?

a) 5'→3' as well

b) 3'→5'

c) In a random direction

d) From the centromere to the telomere

B

What is a nucleolar organizer region (NOR)?

a) A region that forms the centromere

b) A region that contains genes for ribosomal RNA (rRNA)

c) A region that contains genes for histones

d) A region that contains telomerase

B

On which human chromosomes are NORs located?

a) 1, 2, 3, 4, 5

b) 13, 14, 15, 21, 22

c) 16, 17, 18, 19, 20

d) X and Y chromosomes

C

What is the process by which a cell's telomeres become too short, causing it to stop dividing?

a) Apoptosis

b) Necrosis

c) Cellular senescence

d) Mitosis

C

What is the term for a chromosome that looks like an "X" when duplicated?

a) Single chromosome

b) Chromatin

c) Duplicated chromosome

d) Sister chromatid

C

The term "single chromatid" refers to a chromosome that is:

a) Duplicated and looks like an "X"

b) Unduplicated and has only one arm

c) Unduplicated and consists of a single strand

d) Duplicated and consists of two strands

C

What is the main function of the centromere during cell division?

a) To protect the ends of the chromosome

b) To synthesize new DNA strands

c) To hold sister chromatids together and serve as an attachment site for spindle fibers

d) To produce ribosomal RNA

C

The process of DNA replication follows a semi-conservative model, which means each new DNA molecule consists of:

a) Two new strands

b) Two old strands

c) One old strand and one new strand

d) A mix of old and new fragments on each strand

C

In the context of DNA replication, what is the term for the short fragments synthesized on the lagging strand?

a) Nucleosomes

b) Kinetochores

c) Okazaki fragments

d) Telomeres

B

What is the primary function of telomeres in normal cell division?

a) They ensure proper chromosome movement during anaphase.

b) They protect chromosome ends from degradation and fusion.

c) They provide a starting point for DNA polymerase.

d) They hold sister chromatids together.

B

In the flow of genetic information related to blood banking, what is the correct sequence from DNA to a physical trait?

a) Gene → Protein → DNA → Blood type antigen

b) Base → Nucleotide → DNA → Gene → Protein → Blood type antigen

c) Nucleotide → Gene → DNA → Protein → Blood type antigen

d) DNA → Protein → Gene → Blood type antigen

B

What is the term for the process that ends with four haploid daughter cells, each with half the number of chromosomes as the parent cell?

a) Mitosis

b) Meiosis II

c) Apoptosis

d) DNA replication

C

What does the term "haploid" (n) mean in the context of a cell?

a) It has a full set of chromosomes.

b) It has double the number of chromosomes.

c) It has half the number of chromosomes compared to the parent cell.

d) It has no chromosomes.

D

What is the term for the type of DNA found in plants that is involved in photosynthesis?

a) Mitochondrial DNA

b) Nuclear DNA

c) Ribosomal DNA

d) Chloroplast DNA

D

Which of the following best describes a gene?

a) A threadlike structure in the nucleus

b) The observable traits of an organism

c) A different version of a trait

d) A segment of DNA that codes for a specific protein

B

What does the "double helix" describe in the context of DNA?

a) The two arms of a chromosome

b) The two strands of DNA that wrap around each other

c) The process of DNA replication

d) The structure of a nucleotide

B

The fact that Adenine (A) always pairs with Thymine (T) and Guanine (G) always pairs with Cytosine (C) is known as the:

a) Double helix rule

b) Chargaff's rule

c) Replication rule

d) Antiparallel rule

C

What is a sister chromatid?

a) The opposite arm of a chromosome

b) A chromosome that has been duplicated

c) One of the two identical copies of a chromosome held together by a centromere

d) A strand of RNA

C

What is the term for the proteins found on red blood cell surfaces that are determined by the sequence of nitrogenous bases in DNA and define blood type?

a) Enzymes

b) Histones

c) Antigens

d) Kinetochores

B

What is the function of single-strand binding proteins (SSBPs) during DNA replication?

a) To unwind the double helix

b) To stabilize the unwound strands

c) To add new nucleotides

d) To seal gaps in the DNA backbone

B

What is the function of primase during DNA replication?

a) To unwind the DNA helix

b) To add an RNA primer to provide a starting point for DNA polymerase

c) To seal the DNA fragments

d) To add complementary nucleotides

A

What is the name for the DNA strand that is synthesized continuously during replication?

a) Leading strand

b) Lagging strand

c) Template strand

d) Okazaki strand

B

What is the name for the DNA strand that is synthesized in short, fragmented pieces during replication?

a) Leading strand

b) Lagging strand

c) Template strand

d) Okazaki strand

C

Which of the following is true about heterochromatin?

a) It is transcriptionally active.

b) It is gene-rich.

c) It replicates late in the S-phase.

d) It stains lighter under a microscope.

C

Which of the following is true about euchromatin?

a) It is tightly packed.

b) It is transcriptionally inactive.

c) It is gene-rich.

d) It stains darker under a microscope.

C

What is the role of the kinetochore in chromosome movement?

a) It acts as a protective cap.

b) It helps in DNA replication.

c) It is the site where spindle fibers attach to pull chromosomes apart.

d) It contains genes for ribosomal RNA.

C

The fact that telomere length gradually decreases over a person's lifespan is linked to:

a) Increased risk of cancer

b) Continuous cell division

c) Aging and a decline in organ function

d) A strong immune response

C

What is the function of the nucleolus in a cell?

a) It is the control center that contains chromosomes.

b) It is where DNA replication occurs.

c) It is the site where ribosomal subunits are assembled.

d) It is responsible for programmed cell death.

C

What is the chemical material of inheritance that influences all aspects of the structure and function of the human body?

a) Protein

b) RNA

c) DNA

d) Histone

A

The term "antiparallel" in DNA refers to the fact that:

a) The two strands run in opposite directions.

b) The two strands are not connected.

c) The two strands are identical.

d) The two strands are parallel but never touch.

C

What is the name for the repetitive DNA sequences that are found at the centromere?

a) Telomeres

b) Kinetochores

c) Centromere DNA

d) Nucleolar organizer regions

D

The primary constriction on a metaphase chromosome is another name for the:

a) Telomere

b) p arm

c) q arm

d) Centromere

D

What is the highest level of DNA organization, where supercoiled solenoids are further condensed into a visible structure during cell division?

a) DNA helix

b) Nucleosome

c) Solenoid

d) Chromosome

D

What is a "chromatid"?

a) A single, unduplicated chromosome

b) A duplicated chromosome

c) A protein that packages DNA

d) One of the two replicated parts of a chromosome

A

What is the main difference between an RNA nucleotide and a DNA nucleotide?

a) The nitrogenous base (Uracil vs. Thymine) and the pentose sugar (Ribose vs. Deoxyribose).

b) The phosphate group.

c) RNA nucleotides have a different type of protein.

d) DNA nucleotides are found in the nucleus, while RNA nucleotides are not.

C

The genetic code that determines blood group antigens is carried by the sequence of:

a) Amino acids

b) Histones

c) Nitrogenous bases

d) Sugar molecules

C

Which of the following correctly describes the relationship between genes and proteins?

a) Genes are made of proteins.

b) Proteins are made of DNA.

c) Genes contain the instructions for making proteins.

d) Proteins are segments of DNA.

C

What happens when telomeres in a normal cell become too short?

a) The cell undergoes apoptosis.

b) The cell starts to divide indefinitely.

c) The cell enters cellular senescence and stops dividing.

d) The cell's genes become more active.

B

Why are G-C pairs stronger and more stable than A-T pairs?

a) Because they are found in different parts of the DNA molecule.

b) Because they are held together by three hydrogen bonds.

c) Because they are made of different types of purines and pyrimidines.

d) Because they are located at the ends of chromosomes.

B

What are the two types of sex chromosomes in humans?

a) A and B

b) X and Y

c) O and A

d) P and Q

D

Which of the following is a characteristic of heterochromatin?

a) It is less condensed.

b) It is gene-rich.

c) It is transcriptionally active.

d) It stains darker.

B

What is the difference between a duplicated chromosome and a single chromosome?

a) A duplicated chromosome is made of RNA, while a single chromosome is made of DNA.

b) A duplicated chromosome has two sister chromatids, while a single chromosome has one.

c) A duplicated chromosome is found in the cytoplasm, while a single chromosome is in the nucleus.

d) There is no difference; the terms are interchangeable.

B

What is the main purpose of the tight organization of DNA into chromatin and chromosomes?

a) To prevent DNA from being replicated.

b) To allow the long DNA molecule to fit inside the tiny nucleus.

c) To activate genes for protein synthesis.

d) To protect the DNA from viruses.

B

In the library analogy from the source, what does a chromosome represent?

a) The library itself

b) A book inside the library

c) The text written in the book

d) The alphabet letters making up the text

B

What is the significance of the 5' and 3' ends of a DNA strand?

a) They determine the length of the strand.

b) They refer to the carbon atoms in the sugar molecule and give the strand directionality.

c) They are the sites where telomeres are located.

d) They indicate whether the strand is a purine or a pyrimidine.

A

The process of crossing over, which leads to genetic variation, occurs during which stage of meiosis?

a) Prophase I

b) Metaphase I

c) Anaphase II

d) Telophase II

B

What is the product of meiosis II?

a) Two diploid cells

b) Four haploid cells

c) Two haploid cells

d) One diploid and one haploid cell

A

What is the definition of a gene, according to the provided text?

a) A segment of DNA that codes for a specific protein/trait.

b) A structure made of DNA and proteins.

c) A single strand of DNA.

d) A variation of a trait.

C

In the context of a duplicated chromosome, what is the term for the two identical copies?

a) Chromatin

b) Centromeres

c) Sister chromatids

d) Nucleosomes

B

How is the telomerase enzyme linked to cancer?

a) It causes telomere shortening, which triggers tumor growth.

b) It is abnormally reactivated in many cancer cells, allowing them to divide indefinitely.

c) It is responsible for DNA mutations that cause cancer.

d) It helps prevent cancer by limiting cell divisions.

B

What is the primary difference between a nucleotide and DNA?

a) A nucleotide is a polymer, while DNA is a monomer.

b) A nucleotide is a single building block, while DNA is a long chain of nucleotides.

c) A nucleotide has a sugar-phosphate backbone, while DNA does not.

d) A nucleotide contains a protein, while DNA does not.

C

The constricted region that holds sister chromatids together is called the:

a) Telomere

b) p arm

c) Centromere

d) q arm

C

In humans, the two kinds of chromosomes are:

a) Autosomes and genes

b) Genes and alleles

c) Autosomes and sex chromosomes

d) Sex chromosomes and histones

C

What is a key characteristic of a metacentric chromosome?

a) It has a centromere very close to one end.

b) It is only found in non-human species.

c) Its centromere is in the middle, and its arms are of equal length.

d) Its centromere is slightly off-center.