VAID'S ICS – Best UPSC Anthropology Coaching in Delhi Since 1985

Comprehensive Classroom Course · Admissions openRegister now
+91 93113 37737
  • +91-93113 37737, +91-99999 46748
  • 73(FF), Old Rajender Nagar Market, Delhi - 110060
  • MON to SUN 9.00 am - 6.00 pm
Facebook Youtube Instagram
Menu
Enquire Now
Home/Anthropology/Mains PYQ/2021/Paper I/Human Genetics & Human Biology
UPSC MainsAnthropology Optional Paper I 2021 15 Marks Model Answer Available

Chromosomal Aberrations and the Human Body and Mind — 2021 Paper I

Question · 2021 · Paper I · 15 Marks

“Chromosomal aberrations can play havoc with the human body and mind.” Explain with suitable examples.

Model Answer

VAID ICS

Approach

  • Demand of Question: Explain how numerical and structural chromosomal abnormalities disturb physical growth, reproduction and neurodevelopment.
  • Structuring the Response: Define chromosomal aberrations → classify them → illustrate effects on body and mind through major syndromes.
  • Key Dimensions to Cover: Aneuploidy, nondisjunction, deletion, translocation, Down, Turner, Klinefelter and Cri-du-chat syndromes.

Model Answer

Introduction

Chromosomal aberrations are alterations in the number or structure of chromosomes that disturb normal gene dosage and development. They may be numerical—such as trisomy or monosomy—or structural, such as deletion, duplication, inversion and translocation. Their effects may involve morphology, growth, fertility, organ systems and intellectual or behavioural development.

Numerical Aberrations

Numerical abnormalities commonly arise through nondisjunction during meiosis or mitosis, producing aneuploid cells.

  • Down syndrome — Trisomy 21: Lejeune, Gautier and Turpin (1959) demonstrated the chromosomal basis of Down syndrome as an extra chromosome 21. It may produce characteristic craniofacial morphology, hypotonia, short stature, congenital cardiac defects and varying degrees of developmental and intellectual disability.
  • Turner syndrome — 45,X: The chromosomal basis was demonstrated by E. Ford and colleagues (1959). Loss of all or part of one X chromosome commonly produces short stature, gonadal dysgenesis, delayed puberty, infertility and cardiovascular/skeletal abnormalities. A distinctive neurodevelopmental profile may also occur, although overall intelligence is often within the normal range.
  • Klinefelter syndrome — 47,XXY: A. Jacobs and J.A. Strong (1959) identified the XXY chromosomal constitution. Typical manifestations include tall stature, small testes, hypogonadism, gynecomastia and infertility; speech-language, learning and behavioural difficulties may occur.

Structural Aberrations

Structural abnormalities result from chromosomal breakage and abnormal reunion and include deletions, duplications, inversions and translocations. Unbalanced rearrangements alter gene dosage and are therefore more likely to produce developmental abnormalities.

Cri-du-chat syndrome — deletion 5p: Loss of part of the short arm of chromosome 5 causes the characteristic high-pitched “cat-like” cry, craniofacial abnormalities, growth problems, developmental delay and intellectual disability. Severity varies with the size and location of the deletion.

How Chromosomal Aberrations Affect Body and Mind

Chromosomal change Major bodily effect Neurodevelopmental effect
Trisomy 21 Dysmorphism, hypotonia, cardiac defects Intellectual disability
45,X Short stature, ovarian failure Specific learning/neurocognitive difficulties
47,XXY Hypogonadism, infertility Speech/learning difficulties
5p deletion Microcephaly, dysmorphism Developmental and intellectual disability

Thus, the impact reflects gene-dosage imbalance: loss or gain of chromosomal material can disrupt multiple developmental pathways simultaneously.

Conclusion

Chromosomal aberrations demonstrate the intimate relationship between the genome, physical development and neurobehavioural functioning. Their pleiotropic effects explain how a single numerical or structural alteration can simultaneously affect the body, reproductive capacity and mind, making cytogenetic abnormalities important to Biological Anthropology and human genetics.

2026 In what manner is our understanding of serogenetics and cytogenetics useful in reproductive biology? What are the major ethical issues involved in reproductive technology? 2026 Why the classifications of Indian populations, based on somatometric and somatoscopic characteristics failed to develop a common understanding of the population diversity? 2026 Canalization and catch-up growth. 2026 Genetic polymorphism and natural selection.

Want feedback on your answer?

Join the Anthropology workshop or get structured answer-writing guidance from VAID ICS.

Join Workshop Contact VAID ICS

UPSC Anthropology Optional 2021 — Paper I

28 questions

1(a) Animism and Deep Ecology

10 Marks150 words
Syllabus: Paper I > 5. Religion > Forms of religion > Animism
2021Paper IAnthropology of ReligionModel answer available

5(d) Descent Groups

10 Marks150 words
Syllabus: Paper I > 2.5 Kinship > Descent groups
2021Paper IKinshipModel answer available

5(a) Human adolescent growth spurt

10 Marks150 words
Syllabus: Paper I > 10. Human growth and development > Stages of growth > Adolescence
2021Paper IHuman Genetics & Human BiologyModel answer available

5(e) Modes of Subsistence

10 Marks150 words
Syllabus: Paper I > 3. Economic Organization > Modes of subsistence
2021Paper IEconomic & Political AnthropologyModel answer available

5(b) The losses and gains of erect posture

10 Marks150 words
Syllabus: Paper I > 1.5 Characteristics of Primates > Skeletal changes due to erect posture
2021Paper IHuman Evolution & PrimatologyModel answer available

1(e) Thermoluminescence (TL) dating

10 Marks150 words
Syllabus: Paper I > 1.8(a) Chronology: relative and absolute dating methods
2021Paper IPrehistoric ArchaeologyModel answer available