Focuses on the fundamental principles governing genetic inheritance and the mechanisms that create variation among organisms. Includes practice questions to reinforce understanding of these core genetic concepts.
A point mutation occurs when a single nucleotide is altered, but it does not affect the reading frame.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Phenylketonuria (PKU) is caused by a mutation in the gene coding for phenylalanine hydroxylase, leading to the accumulation of phenylalanine.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
A frameshift mutation occurs when a nucleotide is inserted or deleted, shifting the reading frame of the gene.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Thalassemia follows an autosomal recessive pattern, requiring two defective alleles for disease expression.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Turner’s syndrome results from the absence of one X chromosome (45, XO), not the presence of an extra Y chromosome.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
A frameshift mutation occurs when nucleotide insertions or deletions shift the genetic reading frame.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Point mutations involve a single nucleotide change and can be silent, missense, or nonsense mutations.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Point mutations do not always cause frameshift mutations; they can be silent or missense mutations.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Not all mutations are inherited; only those in germ cells can be passed to the next generation.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Klinefelter’s syndrome is caused by the XXY karyotype, not XYY.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Klinefelter’s syndrome is characterized by an extra X chromosome, resulting in a 47, XXY karyotype.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
Aneuploidy occurs when there is an abnormal number of chromosomes, such as in Down’s syndrome (trisomy 21).
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders
