Chromosomes

Chromosomes MDCAT MCQs with answers

39 past paper MCQs on Chromosomes, from the Cell Structure and Function unit of MDCAT Biology. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.The nucleus takes up dyes because of the presence of: (MDCAT 2024)

  1. chromatin
  2. lipid
  3. metal ions
  4. thylakoids
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Correct answer: (a) chromatin

Chromatin, the DNA with its histones, is what the basic stains bind to.

2.Chromosomes were first observed by: (MDCAT 2024)

  1. T. H. Morgan
  2. Griffith
  3. Walther Flemming
  4. Mendel
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Correct answer: (c) Walther Flemming

Flemming saw and named the stained threads in dividing cells.

3.What is the function of a centromere? (UHS MDCAT 2025)

  1. To protect the ends of chromosomes
  2. To hold sister chromatids together
  3. To carry genetic information
  4. To initiate DNA replication
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Correct answer: (b) To hold sister chromatids together

The centromere is the constriction that holds the two sister chromatids together until anaphase.

4.A mature duplicated chromosome consists of: (UHS MDCAT 2025)

  1. Two identical double helical DNA molecules
  2. Two different double helical DNA molecules
  3. A double helical DNA molecule distributed in both chromatids
  4. Histone chains wrapped around DNA core
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Correct answer: (a) Two identical double helical DNA molecules

Replication leaves two sister chromatids, and each is one complete double helix identical to the other.

5.Identify the most appropriate function of chromosomes (UHS MDCAT 2025)

  1. Energy production and storage
  2. Protein synthesis and regulation
  3. Storage of genetic information
  4. Lipid metabolism and transport
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Correct answer: (c) Storage of genetic information

A chromosome is DNA wound on histones, and its work is to hold and pass on the genetic information.

6.________ arranges the DNA Into the chromosomes in a eukaryotic cell. (UHS MDCAT 2025)

  1. Hormones
  2. Elastin
  3. Histone
  4. Nucleosome
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Correct answer: (c) Histone

Histones are the basic proteins the DNA winds around to make the nucleosomes of a chromosome.

7.The contracted region of a chromosome that attaches to spindle fiber is called: (KMU MDCAT 2025)

  1. Telomere
  2. Chromatin
  3. Centromere
  4. Nucleosomes
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Correct answer: (c) Centromere

The centromere is the narrow region carrying the kinetochore to which the spindle fibres attach.

8.The number of chromosomes in a haploid cell are: (KMU MDCAT 2025)

  1. Half the chromosomes in a normal body cell
  2. Double the chromosomes in a normal body cell
  3. Quarter the chromosomes in a normal body cell
  4. Equal to the chromosomes in a normal body cell
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Correct answer: (a) Half the chromosomes in a normal body cell

A haploid cell carries one set of chromosomes, half the diploid number of a body cell.

9.What is the chemical composition of chromosomes? (SIBA MDCAT 2025)

  1. RNA and lipids
  2. DNA and proteins
  3. Carbohydrates and nucleic acids
  4. Proteins and carbohydrates
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Correct answer: (b) DNA and proteins

A chromosome is DNA wound on histone proteins.

10.In chromosome, positively charged histone proteins are organized with negatively charged DNA. The positive charges of histone are due to an abundance of basic amino acids: (SZABMU MDCAT 2025)

  1. arginine and alanine
  2. arginine and lysine
  3. lysine and alanine
  4. phenylalanine and arginine
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Correct answer: (b) arginine and lysine

Arginine and lysine carry basic side chains, which is what gives histones their positive charge.

11.The nucleus takes dyes due to the presence of (UHS MDCAT 2024)

  1. Chromatin
  2. Lipid
  3. Metal ions
  4. Thylakoids
Show answer

Correct answer: (a) Chromatin

Chromatin is the DNA and histone that take up basic stains.

12.Chromosomal abnormality in Turner syndrome is represented by? (UHS MDCAT 2024)

  1. XXX
  2. XYY
  3. XO
  4. XXY
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Correct answer: (c) XO

Turner syndrome is a single X with no second sex chromosome.

13.The chromosomes was first observed by; (UHS MDCAT 2024)

  1. T. H Morgan
  2. Griffith
  3. Walther
  4. Mendel
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Correct answer: (c) Walther

Walther Flemming first saw and described the chromosomes in dividing cells.

14.Where are spindle fibres attached on a chromosome during cell division (KMU MDCAT 2024)

  1. Centromere
  2. Histone proteins
  3. Nucleolus
  4. Telomere
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Correct answer: (a) Centromere

The spindle fibres attach at the kinetochore of the centromere.

15.Chromosome is typically made up from a combination of? (KMU MDCAT 2024)

  1. DNA and protein
  2. DNA and RNA
  3. RNA and lipids
  4. RNA and proteins
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Correct answer: (a) DNA and protein

A chromosome is DNA wound on histone protein.

16.Nucleo proteins are involved in: (NUMS MDCAT 2024)

  1. Cell to cell recognition
  2. Passing hereditary information to next generation
  3. Ensuring fast speed of nerve impulse
  4. Acting as a cell surface marker
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Correct answer: (b) Passing hereditary information to next generation

Nucleoproteins are the DNA and histone of the chromosomes, which carry the inheritance.

17.The terminal ends of chromosomes are called: (SZABMU MDCAT 2023)

  1. Satellite
  2. Kinetochore
  3. Nucleolar organizers
  4. Telomeres
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Correct answer: (d) Telomeres

The ends of a chromosome are capped by telomeres, which keep it from fraying.

18.Which of the following number of chromosomes are present in the somatic cells of Drosophila? (PMC MDCAT 2022)

  1. 4
  2. 8
  3. 16
  4. 2
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Correct answer: (b) 8

Drosophila has four pairs, eight chromosomes in a body cell.

19.Which of the following is the number of chromosomes in human zygote? (PMC MDCAT 2022)

  1. n
  2. 2n
  3. 3n
  4. 4n
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Correct answer: (b) 2n

The zygote has both sets, so it is diploid, $2n$.

20.Except during nuclear division, the nucleus has the chromosome in a loosely coiled state known as: (NUMS MDCAT 2022)

  1. Genes
  2. Ribosomes
  3. DNA
  4. Chromatin
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Correct answer: (d) Chromatin

Between divisions the chromosomes are extended as chromatin.

21.The terminal ends of the chromosomes are called: (NUMS MDCAT 2022)

  1. Satellite
  2. Kinetochore
  3. Nucleolar organizer
  4. Telomere
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Correct answer: (d) Telomere

The ends of a chromosome are its telomeres.

22.Extremely long molecule of DNA that is tightly folded to fit inside the cell component is called? (PMC Practice 2021)

  1. Nucleus
  2. Chromosome
  3. Chromatin body
  4. Chromatid
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Correct answer: (b) Chromosome

A chromosome is one very long DNA molecule folded on its histones.

23.How many pairs of homologous chromosomes are present in Pisum sativum? (PMC Practice 2021)

  1. 5
  2. 6
  3. 7
  4. 8
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Correct answer: (c) 7

The garden pea has fourteen chromosomes, that is seven pairs.

24.At what phase the DNA content of a cell is doubled? (PMC MDCAT 2020)

  1. Prophase
  2. Interphase
  3. Anaphase
  4. Telophase
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Correct answer: (b) Interphase

DNA is replicated in the S phase of interphase, before division begins.

25.The cells in our body are all genetically identical, apart from the: (PMC MDCAT 2020)

  1. Somatic cells
  2. Reproductive cells
  3. Muscle fibers
  4. White blood cells
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Correct answer: (b) Reproductive cells

Meiosis and crossing over make every gamete different.

26.The particular array of chromosomes that an individual possesses is called its: (PMC MDCAT 2020)

  1. Genotype
  2. Phenotype
  3. Karyotype
  4. Allele
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Correct answer: (c) Karyotype

The number, size and shape of the chromosomes of an individual is its karyotype.

27.Microtubule subunits (for spindle fibers) are synthesized in _______ phase. (UHS MDCAT 2019)

  1. G1
  2. M
  3. G2
  4. S
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Correct answer: (c) G2

The proteins for the spindle are made in G2, after replication and before division.

28.The phase of mitosis in which sister chromatids move towards opposite poles: (UHS MDCAT 2019)

  1. Anaphase
  2. Metaphase
  3. Prophase
  4. Telophase
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Correct answer: (a) Anaphase

The sister chromatids are pulled apart at anaphase.

29.During the G2 phase: (UHS MDCAT 2019)

  1. Chromosome number is duplicated
  2. The chromosomes are left with only one chromatid
  3. Energy is stored for Chromosome movement and mitotic specific proteins(Tubulin) are produced
  4. Specific enzymes are synthesized and DNA base units are accumulated
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Correct answer: (c) Energy is stored for Chromosome movement and mitotic specific proteins(Tubulin) are produced

G2 is the gap in which the proteins of the spindle are made and energy is laid in for division.

30.Synthesis of microtubules increases in: (UHS MDCAT 2018)

  1. M phase
  2. S phase
  3. G1 phase
  4. G2 phase
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Correct answer: (d) G2 phase

The tubulin of the spindle is made in G2, after replication and before division.

31.They serve as a scaffold for formation of higher order chromatin structure: (UHS MDCAT 2018)

  1. Nucleosome
  2. Nucleus
  3. Chromosomes
  4. Histones
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Correct answer: (a) Nucleosome

The nucleosome, DNA wound on its histone octamer, is the first level of chromosome coiling.

32.Human female differs from human male in having (UHS MDCAT 2017)

  1. Y chromosome
  2. X chromosome
  3. XY chromosome
  4. XX chromosome
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Correct answer: (d) XX chromosome

A woman has two X chromosomes; a man has an X and a Y.

33.Which of the following is an example of autosomal non-disjunction? (UHS MDCAT 2016)

  1. Turner’s Syndrome
  2. Jacob’s Syndrome
  3. Metastasis
  4. Down’s syndrome
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Correct answer: (d) Down’s syndrome

Down syndrome is an extra chromosome 21, an autosome that failed to separate.

34.Down’s syndrome is characterized by _____________ at chromosome 21. (UHS MDCAT 2016)

  1. Trisomy
  2. Monosomy
  3. Polysomy
  4. Disomy
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Correct answer: (a) Trisomy

Down syndrome is three copies of chromosome 21.

35.Infertility, short height, webbed neck and low hairline at lack are symptoms of _____________ syndrome. (UHS MDCAT 2016)

  1. Turner’s
  2. Down’s
  3. Edward’s
  4. Patau’s
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Correct answer: (a) Turner’s

Turner syndrome is a single X chromosome with no partner.

36.During maternal mitosis, non-disjunction of autosomal chromosome pair results in the formation of an egg having 24 chromosomes in: (UHS MDCAT 2015)

  1. Klinefelter’s Syndrome
  2. Down’s Syndrome
  3. Turner’s Syndrome
  4. Jacob’s Syndrome
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Correct answer: (b) Down’s Syndrome

An egg with an extra chromosome 21 gives a child with three of them.

37.Typical symptoms like enlarged breasts and small testis in male are attributed to: (UHS MDCAT 2015)

  1. Down’s Syndrome
  2. Turner’s Syndrome
  3. Klinefelter’s Syndrome
  4. Phenylketonuria
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Correct answer: (c) Klinefelter’s Syndrome

Klinefelter syndrome is XXY, with an extra X in the male.

38.Turner’s syndrome is characterized by having: (UHS MDCAT 2015)

  1. Trisomy 21
  2. 44 + XXY
  3. Trisomy 18
  4. 44 + XO
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Correct answer: (d) 44 + XO

Turner syndrome is a single X with no partner.

39.Number of pairs of autosomes in humans in: (UHS MDCAT 2015)

  1. 23
  2. 24
  3. 21
  4. 22
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Correct answer: (d) 22

Of the twenty-three pairs, twenty-two are autosomes and one is the sex pair.

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