Chromosomes MCQs With Answer are essential revision tools for B.Pharm students studying genetics and cytogenetics. This concise, keyword-rich introduction covers chromosomal structure, karyotyping, chromatin organization, mitosis, meiosis, chromosomal abnormalities, gene mapping, and diagnostic techniques like FISH and CGH. Focused on pharmacology-relevant genetics, these MCQs help reinforce concepts such as centromere types, chromosomal banding, aneuploidy, translocations, and dosage compensation. Each question targets core learning outcomes required for drug action, toxicogenomics, and personalized medicine. Clear explanations foster critical thinking needed in pharmacy practice and research. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is a chromosome?
- A linear molecule of carbohydrate
- A complex of DNA and proteins carrying genetic information
- A membrane-bound organelle
- A type of ribonucleic acid
Correct Answer: A complex of DNA and proteins carrying genetic information
Q2. Which proteins are primarily involved in chromatin packaging?
- Actins
- Histones
- Keratin
- Collagen
Correct Answer: Histones
Q3. The basic unit of chromatin is called:
- Helix
- Nucleosome
- Centromere
- Chromatid
Correct Answer: Nucleosome
Q4. During which phase of mitosis do sister chromatids separate?
- Prophase
- Metaphase
- Anaphase
- Telophase
Correct Answer: Anaphase
Q5. A karyotype displays chromosomes arranged by:
- Sequence of nucleotides
- Size and banding pattern
- Number of genes
- Transcriptional activity
Correct Answer: Size and banding pattern
Q6. Which technique is used to detect specific DNA sequences on chromosomes?
- Western blotting
- FISH (Fluorescence In Situ Hybridization)
- Mass spectrometry
- ELISA
Correct Answer: FISH (Fluorescence In Situ Hybridization)
Q7. Aneuploidy refers to:
- Changes in base sequence only
- Loss or gain of individual chromosomes
- Structural rearrangement within a chromosome
- Complete duplication of the genome
Correct Answer: Loss or gain of individual chromosomes
Q8. Down syndrome is most commonly caused by:
- Monosomy X
- Trisomy 21
- Deletion of chromosome 5p
- Balanced translocation between 9 and 22
Correct Answer: Trisomy 21
Q9. Which chromosomal abnormality is characterized by a missing chromosome?
- Aneuploidy
- Monosomy
- Trisomy
- Isochromosome
Correct Answer: Monosomy
Q10. The centromere function is to:
- Initiate DNA replication
- Attach sister chromatids to spindle microtubules
- Transcribe ribosomal RNA
- Serve as origin of translation
Correct Answer: Attach sister chromatids to spindle microtubules
Q11. Telomeres are important because they:
- Code for essential proteins
- Protect chromosome ends from degradation
- Bind transcription factors
- Promote homologous recombination
Correct Answer: Protect chromosome ends from degradation
Q12. Which enzyme extends telomeres in germ cells?
- DNA polymerase I
- Telomerase
- Helicase
- Ligase
Correct Answer: Telomerase
Q13. A reciprocal translocation involves:
- Loss of a chromosomal segment
- Exchange of segments between two chromosomes
- Duplication of a chromosome arm
- Formation of a ring chromosome
Correct Answer: Exchange of segments between two chromosomes
Q14. Cri-du-chat syndrome is associated with:
- Deletion on chromosome 5p
- Trisomy 13
- Inversion on chromosome 9
- Monosomy 21
Correct Answer: Deletion on chromosome 5p
Q15. Which banding technique is commonly used for karyotyping human chromosomes?
- SDS-PAGE
- G-banding (Giemsa)
- Southern blotting
- Co-immunoprecipitation
Correct Answer: G-banding (Giemsa)
Q16. Dosage compensation in mammals is achieved by:
- Increasing transcription from the Y chromosome
- X-chromosome inactivation in females
- Doubling expression from autosomes
- Deleting one X in males
Correct Answer: X-chromosome inactivation in females
Q17. Barr body represents:
- Active Y chromosome
- Inactive X chromosome
- Extra mitochondrial DNA
- Duplicated centromere
Correct Answer: Inactive X chromosome
Q18. Which structure contains sister chromatids joined together?
- Centromere
- Telomere
- Nucleolus
- Ribosome
Correct Answer: Centromere
Q19. Which of the following is a structural chromosomal abnormality?
- Trisomy
- Monosomy
- Translocation
- Polyploidy
Correct Answer: Translocation
Q20. Robertsonian translocation typically involves which chromosomes?
- Small acrocentric chromosomes fused at centromeres
- Large metacentric chromosomes only
- Telomeric fusions of all chromosomes
- Partial deletions of X chromosome
Correct Answer: Small acrocentric chromosomes fused at centromeres
Q21. Which technique compares copy number variations across the genome?
- Western blot
- Comparative genomic hybridization (CGH)
- RT-PCR
- Chromatin immunoprecipitation
Correct Answer: Comparative genomic hybridization (CGH)
Q22. Polyploidy is defined as:
- Loss of single chromosome
- More than two complete sets of chromosomes
- Exchange between nonhomologous chromosomes
- Mutation in a single gene
Correct Answer: More than two complete sets of chromosomes
Q23. The short arm of a chromosome is designated as:
- q
- p
- c
- r
Correct Answer: p
Q24. A chromatid is best described as:
- One half of a replicated chromosome
- A circular DNA molecule
- The entire genome
- A mitochondrial fragment
Correct Answer: One half of a replicated chromosome
Q25. Which disorder results from nondisjunction of sex chromosomes producing a single X chromosome?
- Klinefelter syndrome
- Turner syndrome
- Down syndrome
- Edwards syndrome
Correct Answer: Turner syndrome
Q26. Klinefelter syndrome is typically which karyotype?
- 46, XY
- 47, XXY
- 45, X
- 47, XYY
Correct Answer: 47, XXY
Q27. Which chromosome abnormality is associated with chronic myelogenous leukemia (CML)?
- Philadelphia chromosome (t(9;22))
- Trisomy 21
- Deletion 5q
- Duplication 1q
Correct Answer: Philadelphia chromosome (t(9;22))
Q28. Euchromatin is characterized by:
- Transcriptionally inactive, densely packed chromatin
- Transcriptionally active, loosely packed chromatin
- Only found in mitochondria
- Exclusive to prokaryotes
Correct Answer: Transcriptionally active, loosely packed chromatin
Q29. Heterochromatin often contains:
- Highly expressed housekeeping genes
- Repeats and gene-poor regions
- Only telomeric sequences
- Only centromeric proteins
Correct Answer: Repeats and gene-poor regions
Q30. Which method is commonly used to prepare metaphase chromosomes for karyotyping?
- Treating cells with colchicine to arrest mitosis
- Using DNase to fragment DNA
- Transfecting cells with plasmids
- Applying proteases to digest histones
Correct Answer: Treating cells with colchicine to arrest mitosis
Q31. An isochromosome results from:
- Duplication of telomeres
- Mirror-image duplication of chromosome arms
- Loss of entire chromosome
- Insertion of viral DNA
Correct Answer: Mirror-image duplication of chromosome arms
Q32. Microdeletion syndromes are best detected by:
- Standard karyotyping only
- High-resolution techniques like FISH or array CGH
- Protein electrophoresis
- Metabolic assays
Correct Answer: High-resolution techniques like FISH or array CGH
Q33. Which term describes a chromosome that has centromere near the middle?
- Acrocentric
- Metacentric
- Telocentric
- Subtelomeric
Correct Answer: Metacentric
Q34. Homologous chromosomes are:
- Identical sister chromatids
- One paternal and one maternal chromosome with same genes
- Chromosomes in different species
- Only sex chromosomes
Correct Answer: One paternal and one maternal chromosome with same genes
Q35. Crossing over occurs during which meiotic phase?
- Meiosis I prophase (specifically pachytene)
- Meiosis II anaphase
- Mitosis metaphase
- S phase of interphase
Correct Answer: Meiosis I prophase (specifically pachytene)
Q36. The Philadelphia chromosome results from a fusion between which genes?
- BCR on 9 and ABL on 22
- ABL on 9 and BCR on 22
- MYC and BCR
- TP53 and BRCA1
Correct Answer: ABL on 9 and BCR on 22
Q37. Which chromosomal alteration can be balanced with no loss of genetic material?
- Deletion
- Duplication
- Balanced translocation
- Inversion with breakpoints in genes
Correct Answer: Balanced translocation
Q38. Which of the following is a consequence of chromosomal duplication?
- Loss of gene function only
- Potential gene dosage effects and novel phenotypes
- Always embryonic lethality
- Reduction of chromosomal size
Correct Answer: Potential gene dosage effects and novel phenotypes
Q39. Which lab technique separates chromosomes by size and shape for visualization?
- Flow cytometry for chromosomes
- G-banded karyotyping
- ELISA
- Mass spectrometry
Correct Answer: G-banded karyotyping
Q40. In cytogenetics, mosaicism means:
- All cells have the same genotype
- Presence of two or more genetically different cell lines in one individual
- Only germline mutations exist
- Chromosomes are fragmented into pieces
Correct Answer: Presence of two or more genetically different cell lines in one individual
Q41. Which term describes relocation of a chromosomal segment to a different chromosome position?
- Deletion
- Insertion
- Translocation
- Amplification
Correct Answer: Translocation
Q42. Which chromosome abnormality often arises from unequal crossing over?
- Point mutation
- Duplication and deletion
- Nondisjunction only
- Telomerase activation
Correct Answer: Duplication and deletion
Q43. Which diagnostic sample is most commonly used for prenatal karyotyping?
- Urine
- Chorionic villus sampling or amniotic fluid cells
- Sputum
- Saliva
Correct Answer: Chorionic villus sampling or amniotic fluid cells
Q44. The centromere divides the chromosome into two arms; the longer arm is called:
- p arm
- q arm
- c arm
- r arm
Correct Answer: q arm
Q45. Which feature distinguishes submetacentric from acrocentric chromosomes?
- Submetacentric has centromere slightly off center; acrocentric has centromere near one end
- Submetacentric is circular; acrocentric is linear
- Submetacentric lacks telomeres
- There is no difference
Correct Answer: Submetacentric has centromere slightly off center; acrocentric has centromere near one end
Q46. Which chromosomal phenomenon contributes to genetic diversity in gametes?
- Nondisjunction during mitosis
- Crossing over and independent assortment
- Telomere shortening
- Histone acetylation only
Correct Answer: Crossing over and independent assortment
Q47. Which is a hallmark of chromosomal instability in cancer cells?
- Consistent diploid karyotype
- High rate of aneuploidy and structural rearrangements
- Absence of mutations
- Stable telomere length
Correct Answer: High rate of aneuploidy and structural rearrangements
Q48. Which genetic technique maps genes by measuring recombination frequencies?
- Linkage mapping
- Western blot
- FISH only
- Southern blot exclusively
Correct Answer: Linkage mapping
Q49. Which statement about sex chromosomes is correct?
- Females are typically XY and males XX
- Sex chromosomes determine biological sex and carry sex-linked genes
- Y chromosome is larger than X chromosome
- Sex chromosomes are always homologous along entire length
Correct Answer: Sex chromosomes determine biological sex and carry sex-linked genes
Q50. Which of the following best describes array CGH advantage over conventional karyotyping?
- Array CGH detects balanced translocations more effectively
- Array CGH has higher resolution to detect submicroscopic copy number variations
- Array CGH sequences whole genomes faster
- Array CGH requires dividing cells only
Correct Answer: Array CGH has higher resolution to detect submicroscopic copy number variations
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