In Unit 22 – Variation and Genetics, you will learn how traits are passed from parents to children and why everyone is a little different. You will study genes and alleles, see how Mendel’s laws explain inheritance, and learn about dominance, blood groups (MN system and Bombay phenotype), multiple alleles, continuously varying traits, and gene linkage.
This unit makes it easy to understand how traits are inherited, why variation happens, and how genes work in real life.
📥 Download Class 12 Biology Unit 22 Variation and Genetics Notes
Get complete and easy-to-understand notes for Class 12 Biology Unit 22, perfect for Punjab Board exams.
Skip to PDF content- Covers: Genes, Alleles, Gene Pool, Mendel’s Laws, Dominance, Blood Groups, Multiple Alleles, Bombay Phenotype, Continuously Varying Traits, Gene Linkage
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📝 MCQs –Variation and Genetics
1. Who is called the father of genetics?
a) Charles Darwin
b) Gregor Mendel ✅
c) Thomas Hunt Morgan
d) James Watson
2. Law of Segregation states that:
a) Genes for different traits are inherited independently
b) Each organism carries two alleles that separate during gamete formation ✅
c) Traits blend in offspring
d) Genes are linked on the same chromosome
3. The Bombay phenotype is associated with which blood group?
a) A
b) B
c) O ✅
d) AB
4. MN blood group system is controlled by:
a) Two different genes
b) A single gene with two alleles ✅
c) Multiple genes
d) Linked genes
5. Continuously varying traits are controlled by:
a) Single gene
b) Multiple genes ✅
c) Only dominant alleles
d) Only recessive alleles
6. Gene linkage means:
a) Genes are on different chromosomes
b) Genes located close together on the same chromosome tend to be inherited together ✅
c) All traits are dominant
d) Traits blend in offspring
7. Dihybrid cross involves:
a) One trait
b) Two traits ✅
c) Three traits
d) Multiple alleles
8. Multiple alleles refer to:
a) Only two forms of a gene
b) More than two forms of a gene ✅
c) Genes on different chromosomes
d) Linked genes
9. Dominance relation refers to:
a) How genes interact to show a trait ✅
b) How alleles separate
c) Gene linkage
d) Continuous variation
10. Mendel used which plant for his experiments?
a) Wheat
b) Pea plant ✅
c) Maize
d) Rice