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Principles of Inheritance and Variation

Tamil Nadu Board · Class 12 · Zoology

Flashcards for Principles of Inheritance and Variation — Tamil Nadu Board Class 12 Zoology. Quick Q&A cards covering key concepts, definitions, and formulas.

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24 Flashcards
Card 1Fundamental Genetics Concepts

What is a gene and what does it represent in the context of heredity?

Answer

A gene is the unit of heredity that is inherited from parents to offspring. It is the basic functional unit of DNA that determines specific biological characteristics and traits in an organism. For ex

Card 2Multiple Alleles

Define multiple alleles and explain why blood group inheritance is a good example of this phenomenon.

Answer

Multiple alleles refer to three or more alternative forms of the same gene that control a particular trait and occupy the same locus on homologous chromosomes. ABO blood groups are an excellent exampl

Card 3ABO Blood Groups

What are the three alleles of the I gene in blood group inheritance, and what does each one produce?

Answer

The three alleles of the I gene are: (1) I^A - produces N-acetyl galactose transferase enzyme, which adds N-acetyl galactosamine to create A antigen; (2) I^B - encodes galactose transferase enzyme, wh

Card 4ABO Blood Groups

If a person has genotype I^A I^O, what will be their ABO blood type and why?

Answer

A person with genotype I^A I^O will have blood type A. This is because the I^A allele is dominant over the I^O allele. Even though they carry one recessive I^O allele, the dominant I^A allele is expre

Card 5Rh Factor

What is the Rh factor, where was it discovered, and what does Rh D positive versus Rh D negative mean?

Answer

The Rh factor (immunogenic D antigen) is a special antigen found on the surface of red blood cells. It was discovered in 1940 by Karl Landsteiner and Alexander Wiener in the blood of the rhesus monkey

Card 6Rh Factor and Incompatibility

What is erythroblastosis foetalis (hemolytic disease of the newborn) and when does it occur?

Answer

Erythroblastosis foetalis (HDN) is a serious hemolytic disease where fetal red blood cells are destroyed due to incompatibility between mother and fetus blood types. It typically occurs when an Rh neg

Card 7Sex Determination

Distinguish between heterogametic males (XX-XY type) and heterogametic females (ZW-ZZ type) in sex determination.

Answer

In heterogametic males (XX-XY system): Males produce two types of gametes (X and Y), while females produce only X gametes. Found in humans and Drosophila. The male offspring sex is determined by wheth

Card 8Sex Determination

What is the SRY gene and what is its role in male development in humans?

Answer

The SRY (Sex determining region Y) gene is located on the Y chromosome and is responsible for male sex determination in humans. The gene product of SRY is the testes determining factor (TDF), which is

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Frequently Asked Questions

What are the important topics in Principles of Inheritance and Variation for Tamil Nadu Board Class 12 Zoology?
Key topics in Principles of Inheritance and Variation include Shows how multiple alleles exist in a population but individuals carry only two; demonstrates the relationship between number of alleles and possible genotypes/phenotypes, Illustrates how three alleles at a single locus produce four distinct blood group phenotypes through different enzyme activities, Shows mapping of six possible genotype combinations to four blood type phenotypes. These are the concepts Tamil Nadu Board Class 12 examiners draw on most — study them first, then practise related questions.
How to score full marks in Principles of Inheritance and Variation — Tamil Nadu Board Class 12 Zoology?
Understand the core concepts first, then work through the 44 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Principles of Inheritance and Variation?
There are 24 flashcards for Principles of Inheritance and Variation covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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