TNPSC Biology Genetics Quiz 1

🧪 Concept Booster – Genetics Quiz For TNPSC

Understanding Genetics TNPSC Questions is important for scoring well in General Science. These Genetics TNPSC MCQs focus on key concepts like heredity, genes, DNA, and Mendel’s laws of inheritance. This section will help you clearly understand each concept with simple explanations and exam-focused points.

This Concept Booster is designed specifically for this quiz to help you understand the topics from which questions are given.

Mendel and Basics of Genetics

Gregor Mendel is known as the Father of Genetics because he studied how traits are inherited from parents to offspring using pea plant experiments. He explained the concepts of heredity and introduced dominant and recessive traits, which form the foundation of genetics.

Key Points

• Father of Genetics → Mendel
• Studied → Inheritance of traits
• Experiment → Pea plants
• Traits → Dominant & Recessive

👉 Remember : Mendel = Genetics

Gene and Its Function

A gene is the basic unit of heredity that carries information for specific traits from parents to offspring. It is a segment of DNA that controls characteristics such as eye color, height, and blood group.

Key Points

• Gene → Unit of heredity
• Made of → DNA
• Located on → Chromosomes
• Controls → Traits

👉 Remember : Gene = Trait

Chromosomes – Gene Location

Genes are located on chromosomes, which are present inside the nucleus of a cell. Chromosomes act as carriers of genetic information and contain many genes arranged in a specific order.

Key Points

• Genes located on → Chromosomes
• Chromosomes found in → Nucleus
• Made of → DNA
• Function → Carry genetic information

👉 Remember : Gene → Chromosome → Nucleus

DNA and Genetic Information

DNA (Deoxyribonucleic Acid) carries genetic information in all living organisms. It stores instructions that control body functions and passes traits from parents to offspring during reproduction.

Key Points

• DNA → Genetic material
• Function → Stores information
• Controls → Body activities
• Found in → Nucleus

👉 Remember : DNA = Life code

Heredity

Heredity is the process by which traits are passed from parents to offspring through genes. It explains why children resemble their parents in features like eye color, height, and other characteristics.

Key Points

• Heredity → Transfer of traits
• From → Parents to offspring
• Controlled by → Genes
• Basis of → Genetics

👉 Remember : Heredity = Inheritance

Structure of Chromosomes

Chromosomes are made up of DNA and proteins. The DNA carries genetic information, while proteins help in packaging and organizing the DNA into a compact structure inside the nucleus.

Key Points

• Made of → DNA + Proteins
• Located in → Nucleus
• Function → Carry genes
• Structure → Thread-like

👉 Remember : Chromosome = DNA + Protein

Chromosome Number in Humans

Human body cells contain 46 chromosomes arranged in 23 pairs. One set of chromosomes is inherited from the mother and the other from the father, which together carry all genetic information.

Key Points

• Total chromosomes → 46
• Arranged as → 23 pairs
• From → Both parents
• Present in → Body (somatic) cells

👉 Remember : 23 pairs = 46 chromosomes

Dominant Trait

A dominant trait is a characteristic that expresses itself even if only one copy of the gene is present. It masks the effect of the recessive trait and appears in the organism.

Key Points

• Dominant trait → Expressed strongly
• Needs → Only one gene
• Masks → Recessive trait
• Example → Tallness in plants

👉 Remember : Dominant = Strong & visible

Recessive Trait

A recessive trait is a characteristic that appears only when both copies of the gene are recessive. It remains hidden in the presence of a dominant trait and expresses only when no dominant gene is present.

Key Points

• Recessive trait → Expressed only in pair
• Needs → Two recessive genes
• Hidden by → Dominant trait
• Example → Shortness in plants

👉 Remember : Recessive = Hidden trait

Structure of DNA

DNA has a double helix shape, which looks like a twisted ladder. This unique structure helps DNA store and transmit genetic information efficiently from one generation to the next.

Key Points

• Shape → Double helix
• Structure → Twisted ladder
• Made of → Nucleotides
• Function → Store genetic information

👉Remember : DNA = Double helix

Mutation

Mutations may occur naturally or due to environmental factors such as radiation and chemicals.

Key Points

• Mutation → Change in DNA
• Causes → Variation
• Occurs → Suddenly
• Effect → Beneficial or harmful

👉Remember : Mutation = Change in DNA

Sex Determination

The sex of a child is determined by the combination of sex chromosomes inherited from both parents. Since the mother contributes only an X chromosome and the father contributes either X or Y, the father’s chromosome determines whether the child is XX (female) or XY (male).

Key Points

• Determined by → Sex chromosomes
• Mother → Always X
• Father → X or Y
• XX → Female, XY → Male

👉 Remember : Father contributes X or Y chromosome

Sex Chromosomes

Human body cells contain 46 chromosomes arranged in 23 pairs. One set of chromosomes is inherited from the mother and the other from the father. However, reproductive cells (gametes) such as sperm and egg contain only 23 chromosomes.

Key Points

• Total chromosomes in humans → 46
• Arranged as → 23 pairs
• Present in → Body (somatic) cells
• Gametes contain → 23 chromosomes
• Inherited from → Both parents

👉 Remember: 23 pairs = 46 chromosomes | Gametes = 23 chromosomes

Phenotype

Phenotype refers to the observable characteristics of an organism. These traits result from the interaction between an organism’s genotype and environmental factors.

Key Points

• Phenotype → Visible traits
• Includes → Appearance & behavior
• Depends on → Genes + environment
• Examples → Height, eye color

👉Remember : Phenotype = What you see

Genotype

Genotype refers to the genetic makeup of an organism. It represents the combination of genes inherited from parents that determines specific traits, though it may not always be visible.

Key Points

• Genotype → Genetic makeup
• Determines → Traits
• Not directly visible
• Example → TT, Tt, tt

👉 Remember : Genotype = Genetic code

Discovery of DNA Structure

The double helix structure of DNA was discovered by James Watson and Francis Crick in 1953. Their discovery helped scientists understand how genetic information is stored and passed from one generation to the next.

Key Points

• Scientists → Watson & Crick
• Discovery → DNA structure
• Shape → Double helix
• Year → 1953

👉 Remember : Watson + Crick = DNA

Function of DNA

DNA is the genetic material that controls all biological activities in living organisms. It stores and transmits genetic information from parents to offspring and directs the formation of proteins needed for growth and development.

Key Points

• DNA → Genetic material
• Stores → Genetic information
• Controls → Body functions
• Transfers → Traits to next generation

👉 Remember : DNA = Control center

Gamete Formation

Gametes (sperm and egg cells) are produced through a special type of cell division called meiosis. This process reduces the chromosome number to half, ensuring that the correct number is maintained after fertilization.

Key Points

• Process → Meiosis
• Produces → Gametes
• Reduces → Chromosome number
• Important for → Reproduction

👉Remember : Meiosis = Gametes

Alleles

Alleles are different forms of the same gene that control a particular trait. They are present at the same position on homologous chromosomes and can result in variations of a trait.

Key Points

• Alleles → Forms of a gene
• Control → Same trait
• Located on → Same chromosome position
• Example → T and t

👉 Remember : Alleles = Variations of a gene

Genetic Diseases

Genetic diseases are disorders caused by defects or mutations in genes or chromosomes. These diseases can be inherited from parents and may affect normal body functions.

Key Points

• Cause → Gene mutation
• Inherited from → Parents
• Affects → Body functions
• Example → Hemophilia, Color Blindness, Sickle Cell Anemia

👉 Remember : Genetic disease = Inherited disorder

Homozygous and Heterozygous

Homozygous

• Both alleles are identical
• Example: TT, tt
• Also called pure trait

👉 Remember: Homo = Same

Heterozygous

• Alleles are different
• Example: Tt
• Also called hybrid trait

👉 Remember: Hetero = Different

FINAL REVISION TIPS (GENETICS)

• Mendel → Father of Genetics
• Gene → Unit of heredity
• Gene located on → Chromosome
• DNA → Carries genetic information
• 23 pairs = 46 chromosomes in humans
• Dominant → Expressed, Recessive → Hidden
• DNA shape → Double helix
• XX → Female, XY → Male
• Phenotype → Visible traits, Genotype → Genetic makeup
• Meiosis → Produces gametes
• Alleles → Different forms of gene
• Genetic disease → Inherited disorder

👉 Revise keywords, not paragraphs — TNPSC asks direct concepts

🔗 Authority Reference:
Read NCERT Class 10 Science – Heredity and Evolution (Official Source)