NEET Biology Genetics MCQs

Genetics in NEET Biology MCQs

Basic Concepts of Genetics
- Definition of Genetics: Study of heredity and variation.
- Genes: Units of heredity made of DNA.
- Alleles: Different forms of a gene (dominant and recessive).
Mendelian Genetics
- Gregor Mendel: Father of genetics; conducted pea plant experiments.
- Laws of Inheritance:
  - Law of Segregation: Alleles separate during gamete formation.
  - Law of Independent Assortment: Genes for different traits segregate independently.
Genotype and Phenotype
- Genotype: Genetic makeup of an organism (e.g., AA, Aa, aa).
- Phenotype: Observable traits (e.g., flower color).
- Homozygous vs. Heterozygous:
  - Homozygous: Identical alleles (AA or aa).
  - Heterozygous: Different alleles (Aa).
Punnett Squares
- Tool for predicting offspring genotypes and phenotypes from parental crosses.
- Monohybrid crosses: Single trait analysis.
- Dihybrid crosses: Two traits analysis (e.g., AaBb x AaBb).
Non-Mendelian Inheritance
- Incomplete Dominance: Blending of traits (e.g., red and white flowers producing pink).
- Codominance: Both alleles expressed (e.g., AB blood type).
- Multiple Alleles: More than two alleles for a trait (e.g., ABO blood group).
- Polygenic Inheritance: Trait controlled by multiple genes (e.g., skin color).
Chromosomal Genetics
- Chromosomes: Structures carrying genes; humans have 46 (23 pairs).
- Sex-linked traits: Traits associated with genes on sex chromosomes (e.g., color blindness).
- Karyotype: Visual representation of chromosomes.
Mutation
- Definition: Permanent alteration in DNA sequence.
- Types of mutations:
  - Point mutations: Changes in a single nucleotide.
  - Chromosomal mutations: Deletions, duplications, inversions, translocations.
Genetic Disorders
- Caused by mutations or chromosomal abnormalities.
- Examples:
  - Autosomal recessive disorders (e.g., cystic fibrosis).
  - Autosomal dominant disorders (e.g., Huntington's disease).
  - Sex-linked disorders (e.g., hemophilia).
Biotechnology in Genetics
- Techniques: DNA sequencing, CRISPR-Cas9, cloning.
- Applications: Gene therapy, genetically modified organisms (GMOs).
Important Terminology
- Phenotypic Ratio: Ratio of different phenotypes in offspring.
- Genotypic Ratio: Ratio of different genotypes in offspring.
- Test Cross: Cross between an individual with an unknown genotype and a homozygous recessive individual.
Sample MCQs Topics
- Identify genotypes from given phenotypes.
- Predict offspring ratios from Punnett squares.
- Differentiate between types of inheritance patterns.
- Recognize examples of genetic disorders based on inheritance patterns.

Basic Concepts of Genetics

Genetics is the study of heredity and variation in organisms.
Genes are the fundamental units of heredity made from DNA, responsible for traits.
Alleles are alternative forms of a gene, categorized as dominant or recessive.

Mendelian Genetics

Gregor Mendel, the father of genetics, is known for his experiments with pea plants which laid the foundation for inheritance laws.
Law of Segregation indicates that alleles for a trait separate during gamete formation.
Law of Independent Assortment states that genes for different traits segregate independently during gamete formation.

Genotype and Phenotype

Genotype refers to an organism's genetic composition (e.g., AA, Aa, aa).
Phenotype is the observable physical or biochemical characteristics (e.g., flower color).
Homozygous individuals have identical alleles (AA or aa), while heterozygous individuals have different alleles (Aa).

Punnett Squares

Punnett squares are used to predict the genotypes and phenotypes of offspring from parental crosses.
Monohybrid crosses analyze the inheritance of a single trait.
Dihybrid crosses investigate the inheritance of two traits simultaneously (e.g., AaBb x AaBb).

Non-Mendelian Inheritance

Incomplete dominance occurs when traits blend together (e.g., red and white flowers producing pink).
In codominance, both alleles are expressed equally (e.g., AB blood type).
Traits may be influenced by multiple alleles, such as in the ABO blood group system.
Polygenic inheritance involves multiple genes affecting a single trait (e.g., skin color).

Chromosomal Genetics

Chromosomes are structures that house genes; humans typically have 46 chromosomes organized in 23 pairs.
Sex-linked traits are linked to genes found on sex chromosomes (e.g., color blindness).
A karyotype is a visual display of an individual's chromosomes used for genetic analysis.

Mutation

A mutation is a permanent change in the DNA sequence of an organism.
Point mutations involve alterations at a single nucleotide, whereas chromosomal mutations can involve deletions, duplications, inversions, or translocations.

Genetic Disorders

Genetic disorders often arise from mutations or chromosomal irregularities.
Autosomal recessive disorders, like cystic fibrosis, require two copies of the defective gene to manifest.
Autosomal dominant disorders, such as Huntington's disease, require only one copy of the defective gene to express the disorder.
Sex-linked disorders, for example, hemophilia, are associated with genes on sex chromosomes.

Biotechnology in Genetics

Key techniques include DNA sequencing, CRISPR-Cas9 gene editing, and cloning.
Applications of these technologies involve gene therapy and the creation of genetically modified organisms (GMOs).

Important Terminology

The phenotypic ratio denotes the proportion of different phenotypes in the offspring.
The genotypic ratio indicates the proportion of different genotypes resulting from a genetic cross.
A test cross is performed between an individual of unknown genotype and a homozygous recessive individual to determine the unknown genotype.

Sample MCQs Topics

Ability to derive genotypes from presented phenotypes.
Predicting offspring ratios using Punnett squares.
Distinguishing between various inheritance patterns.
Identifying examples of genetic disorders based on their inheritance mechanisms.