Q.Name a human genetic disorder due to the following :
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🔒 Start your 14-day free trial to unlock the full solution →Part (a)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 …
Part (b)Concept understanding — Mendelian Genetics Basics
Mendelian Genetics Basics
Imagine you have a box of coloured beads — red and white. If you pick one bead from the box, you get either red or white. Now imagine that the colour of your eyes, or the shape of your earlobe, is decided by something like that: a tiny "packet" inside your cells that comes in two versions, and you inherit one from each parent. That is the core idea of Mendelian genetics.
The everyday intuition
You have probably noticed that children often look like their parents — same hair colour, same dimples, same height. But they are never exact copies. Why? Because each parent contributes half of the "instructions" for building a child. Those instructions come in pairs, one from mother and one from father. Sometimes one instruction overrides the other; sometimes they blend. Gregor Mendel, a 19th-century monk, figured out the rules by watching pea plants — tall vs short, yellow vs green seeds — and counting what appeared in the next generation.
The precise meaning
Mendelian genetics is the study of how traits are passed from parents to offspring through genes. A gene is a unit of heredity — a stretch of DNA that codes for a specific characteristic, like flower colour. Each gene comes in different versions called alleles. For every gene, you inherit two alleles: one from your mother, one from your father.
If the two alleles are identical, you are homozygous for that trait. If they are different, you are heterozygous. In a heterozygous pair, one allele may be dominant — it shows up in the appearance — and the other recessive — it stays hidden unless both alleles are recessive.
Mendel's key insight was that traits are not blended like paint. Instead, alleles remain separate and are passed on intact. A recessive allele can skip a generation and reappear later, unchanged.
Why it matters
Mendelian genetics is the foundation of modern biology. It explains:
- Why some diseases run in families (like cystic fibrosis or sickle-cell anaemia)
- How plant and animal breeders create new varieties
- Why you might have your grandmother's eyes but not your mother's
The NCERT textbook states that Mendel's work established the laws of inheritance — the Law of Dominance, the Law of Segregation, and the Law of Independent Assortment. These laws describe how alleles separate during the formation of eggs and sperm, and how different genes are inherited independently of one another.
Key terms at a glance
- Gene: a unit of heredity on a chromosome
- Allele: a variant form of a gene
- Dominant: the allele that expresses itself even when paired with a different allele
- Recessive: the allele that expresses itself only when paired with an identical recessive allele
- Homozygous: having two identical alleles for a gene
- Heterozygous: having two different alleles for a gene …
Part (a)
(a) Additional X-chromosome in a male (47, XXY): Klinefelter's syndrome. …
Part (a): additional X in a male → Klinefelter's syndrome (XXY); loss of an X in a female → Turner's syndrome (XO).
Part (b): aneuploidy → genetic disorders / developmental abnormalities from unbalanced chromosome number.
Part (a)
A normal human has 46 chromosomes (23 pairs); errors in chromosome number cause specific syndromes.
- (a) An additional X-chromosome in a male gives a karyotype of 47, XXY. This causes Klinefelter's syndrome — the individual is phenotypically male but often shows some feminine features (e.g. gynaecomastia), small testes and sterility. …
- JKBOSE Class 12 Annual Regular Examination 2022Set BOTANY1 markMCQQ.The genotype of a plant showing a dominant phenotype can be determined by :(a) Back cross(b) Test cross(c) Dihybrid cross(d) Pedigree analysis
›Reveal solutionSolution
A test cross — crossing the dominant-phenotype plant with a homozygous recessive plant — is the standard way to determine an unknown genotype, because the recessive parent contributes only recessive alleles, so the offspring ratio directly reveals the unknown parent's gametes.
How it works: Let the dominant phenotype be produced either by genotype AA (homozygous) or Aa (heterozygous) — the two look identical. Cross the unknown plant with the recessive parent (aa):
- If the unknown parent is AA: AA × aa → all offspring Aa → 100% dominant phenotype.
- If the unknown parent is Aa: Aa × aa → offspring 1 Aa : 1 aa → 1:1 ratio of dominant : recessive phenotype.
So observing the offspring ratio tells us the genotype of the parent showing the dominant trait. Mendel himself used this method to confirm his law of segregation.
Why the other options don't fit: …
- JKBOSE Class 12 Annual Regular Examination 2021Set BOTANY_B1 markQ.Test cross is cross between an individual and its dominant parent. (True/False)
›Reveal solutionSolution
False. A test cross uses the homozygous recessive parent, not the dominant one.
A test cross is a genetic technique devised to determine the unknown genotype of an individual showing a dominant phenotype (i.e., to distinguish whether it is homozygous dominant, e.g. TT, or heterozygous, e.g. Tt). The individual in question is crossed with a homozygous recessive individual (e.g. tt) — not with a dominant parent.
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- JKBOSE Class 12 Annual Regular Examination 2019Set BOTANY1 markQ.A hybrid is the result of a cross between ......... group of organisms. (Fill in suitable word)
›Reveal solutionSolution
A hybrid is the offspring produced by crossing two genetically dissimilar parents.
Hybrid and hybridization
In genetics, hybridization refers to the crossing (mating) of two genetically dissimilar organisms — parents differing in one or more heritable traits, which may belong to different varieties, strains or, in wider hybridization, even different but related species. The offspring resulting from such a cross is called a hybrid.
This is the basis of Mendel's classic pea-plant experiments: he cross-pollinated true-breeding pea plants that differed in contrasting characters (e.g., tall × dwarf, round seed × wrinkled seed) — genetically dissimilar parents — and studied the traits of their hybrid offspring (F1 generation) and subsequent generations to formulate the laws of inheritance.
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