Q.Write a short note on XX-XY system of sex determination.
🔒You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.
🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Sex Determination — Ethics and Social Misuse
Sex Determination Ethics: A First Look
Imagine a family waiting for a baby. Relatives whisper, "Hope it's a boy" or "Thank God it's a girl." That casual reaction carries a heavy ethical weight. Sex determination ethics is the study of the moral questions surrounding the practice of choosing or knowing the sex of a child before birth, and the social consequences that follow.
The Core Idea
At its simplest, sex determination ethics examines whether it is morally right to use medical technology to find out whether an unborn baby is male or female, and then to act on that information — especially by aborting a fetus of the "unwanted" sex. The ethical problem is not about the technology itself (ultrasound, amniocentesis), but about what people do with that knowledge.
The NCERT textbook for Class 12 (Biology, Chapter 4: Reproductive Health) states this clearly: "Amniocentesis — a technique to determine the sex of the unborn child — is being misused to kill the female foetuses." The textbook calls this a "severe" misuse and links it directly to the declining child sex ratio in India.
Why Does This Become an Ethical Issue?
Three things make sex determination an ethical problem, not just a medical one:
- Discrimination against females. The practice is overwhelmingly used to abort female fetuses. This treats being female as a defect or a burden, which is a form of gender-based violence before birth.
- Social imbalance. When many more boys are born than girls, society faces a shortage of women. This leads to forced marriages, trafficking, and increased violence against women. The NCERT notes that the child sex ratio in India has dropped alarmingly — from 945 females per 1000 males in 1991 to 919 in 2011.
- Violation of the child's right to exist. The fetus is not given a chance to live simply because of its sex. This raises deep questions about equality and the value of every human life.
The Indian government made sex determination illegal under the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act, 1994. This law bans doctors from telling parents the sex of the fetus, and bans any advertisement or test done solely for sex selection. Violation can lead to imprisonment and heavy fines.
The Everyday Intuition
Think of it this way: if you were told that your school would only admit boys next year, you would immediately see that as unfair. Sex determination ethics extends that same intuition to the womb. It asks: Is it fair to decide that a girl should not be born, simply because she is a girl?
The answer, from an ethical standpoint, is no. Every child — boy or girl — has equal moral worth. Using technology to eliminate an entire sex is a form of systematic discrimination that harms individuals and destabilises society.
Why It Matters for a Commerce/Humanities Student
You might think this is a "science topic," but it is deeply connected to what you study:
- Economics: A skewed sex ratio affects labour markets, marriage markets, and long-term economic growth. Fewer women mean fewer workers, consumers, and entrepreneurs.
- Political Science: Laws like the PCPNDT Act are examples of the state intervening to protect fundamental rights (right to life, right to equality). You can analyse how effective such laws are.
- Sociology: Sex determination reflects deep-rooted patriarchy, son preference, and dowry practices. It is a case study in how social norms shape — and are shaped by — technology.
- Ethics (if you study it): This is a classic dilemma: individual choice (parents wanting a son) versus social good (gender balance). Where do you draw the line?
A Few Key Points to Remember …
In the XX-XY system, the two sexes differ in their sex chromosomes and males are heterogametic. …
XX-XY: females XX (homogametic), males XY (heterogametic) — the male's sperm determines sex.
In the XX-XY type of sex determination (found in humans, Drosophila and many mammals):
- The female has two similar sex chromosomes, XX. She is homogametic and forms only one type of egg carrying an X chromosome.
- The male has two different sex chromosomes, XY. He is heterogametic and forms two types of sperm — 50% carrying X and 50% carrying Y. …
- CBSE 2022Set ZOOLOGY1 markMCQQ.Which type of sex determination is found in humans?(i) XX-XY(ii) ZW-ZZ(iii) XX-XO(iv) ZZ-ZO
›Reveal solutionSolution
Humans show the XX-XY type of sex determination, with the male being heterogametic.
In humans, each individual has 22 pairs of autosomes plus one pair of sex chromosomes. Females carry two X chromosomes (XX) and are homogametic, producing only X-bearing eggs. Males carry one X and one Y (XY) and are heterogametic, producing X-bearing and Y-bearing sperm in equal numbers. The sperm therefore determines the …
- CBSE 2022Set ZOOLOGY1 markMCQQ.Which is the genotype of Turner's syndrome?(i) XO(ii) XXY(iii) XYY(iv) XXX
›Reveal solutionSolution
Turner's syndrome has the genotype XO (45, X0) - a single X and no second sex chromosome.
Turner's syndrome arises from monosomy of the sex chromosome due to non-disjunction during gamete formation. The affected individual has 45 chromosomes: 44 autosomes + a single X (XO / 45, X0). Such individuals are sterile females with underdeveloped ovaries, short stature and lack of secondary sexual …
- CBSE 2018Set ANNUAL1 markMCQQ.The number of chromosomes in the individual suffering from Klinefelter's syndrome is :(a)(i) 48(b)(ii) 47(c)(iii) 46(d)(iv) 45
›Reveal solutionSolution
A person with Klinefelter's syndrome has 47 chromosomes — option (ii) — because of an additional X chromosome (44 autosomes+XXY).
Concept
The normal human diploid number is 2n=46 (44 autosomes +2 sex chromosomes). Klinefelter's syndrome is caused by non-disjunction during gamete formation, which leaves the individual with one extra X chromosome.
Why
- Sex-chromosome constitution: XXY instead of XY.
- Total count: 44+XXY=47.
- The individual is phenotypically male but shows feminised features — gynaecomastia (breast development), sparse body hair, and usually sterility.
Contrast …
- CBSE 2018Set ANNUAL1 markQ.Write a short note on XX-XY system of sex determination.
›Reveal solutionSolution
XX-XY: females XX (homogametic), males XY (heterogametic) — the male's sperm determines sex.
In the XX-XY type of sex determination (found in humans, Drosophila and many mammals):
- The female has two similar sex chromosomes, XX. She is homogametic and forms only one type of egg carrying an X chromosome.
- The male has two different sex chromosomes, XY. He is heterogametic and forms two types of sperm — 50% carrying X and 50% carrying Y. …
🎓Unlock everything free for 14 days
- ✓Full step-by-step solutions
- ✓Concept-first explanations
- ✓Methods, shortcuts & mistakes
- ✓PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.