Mendelian Genetics MCQ Quiz - Objective Question with Answer for Mendelian Genetics - Download Free PDF

The correct answer is A, B, and AB.

Key Points

• Blood is a body fluid.
• ABO blood grouping was given by Karl Landsteiner.
• The parent's blood group is AB.
• The blood group proteins are present in the 'I ' gene.
• The genotype of a parent is IA IB.

• From the punnet square, we can see that,
• The Blood group can be A, AB, and B.
• The blood group shows codominance interaction.
• A and B are codominant over the O blood group.
• IAIA = A blood group as here only A  allele is present on the I gene.
• IAIB= AB blood group as here A and B allele is present on the I gene.
• IBIB=B blood group as here B allele is present on the I gene.
• If the blood group of both parents is AB, then the possible blood group of their children will be A, B, and AB.

Additional Information

Correct answer is a, b and c.

Key Points

• Gregor Johann Mendel is known as Father and also founder of Genetics.
• Mendel's law mainly includes the following laws:
  • Law of Dominance
  • Law of Segregation
  • Law of Independent assortment.
• The law of inheritance has come because of his experiments on pea plant.
• It gave monohybrid genotype ratio 1:2:1.

Additional Information

• Genetic drift is nothing but small fluctuations in the number of genes in a population.
• If the gene known as alleles increase and decreases, then gene drift takes place.
• The differences in the presence of alleles are measured as changes in alleles frequencies.
• Heredity is nothing but passing of characteristics genetically from parents to offspring.
• It can be passed either from sexual or asexual reproduction.
• The study of heredity is nothing but genetics.

The correct answer is Ribonucleic Acid.

Key Points

• Ribonucleic Acid (RNA) is believed to be the first genetic material because it can store genetic information and catalyze chemical reactions, unlike DNA, which requires proteins to catalyze reactions.
• RNA can form complex three-dimensional structures, enabling it to perform various biochemical roles, including catalysis and gene regulation.
• In the early evolution of life, RNA molecules, also known as ribozymes, could have played a key role in catalyzing their own replication.
• The "RNA world" hypothesis suggests that life on Earth may have begun with self-replicating RNA molecules before DNA and proteins evolved.

Additional Information

• Cellulose: Cellulose is a polysaccharide that serves as a structural component in the cell walls of plants.
• Mitochondria: Mitochondria are organelles in eukaryotic cells responsible for producing energy through cellular respiration. 
• Deoxyribonucleic Acid (DNA): DNA is the primary genetic material in most organisms today. It stores genetic information and guides the development and functioning of living organisms.

The Correct answer is Round seeds.

Key Points

• Round seeds are a dominant trait in the experiments conducted by Gregor Mendel on garden peas.
• Dominant traits are traits that appear in the F1 generation when two pure lines are crossed.
• In Mendel’s experiments, the round seed shape was observed to be dominant over the wrinkled seed shape.
• Mendel’s principles of dominance and segregation explain how the dominant trait (round seeds) masks the recessive trait (wrinkled seeds) in the F1 generation.
• Mendel's work laid the foundation for the field of genetics, and his experiments with garden peas are considered pioneering.

 Additional Information

• Green seeds
  • Green seeds are a recessive trait in Mendel’s experiments with garden peas.
  • When crossing plants with green seeds and yellow seeds, the F1 generation predominantly shows the yellow seed color, indicating that yellow is dominant.
• Wrinkled seeds
  • Wrinkled seeds are another recessive trait observed by Mendel.
  • The trait only appears in the F2 generation when two heterozygous round-seeded plants are crossed.
• Short plants
  • Short plants are recessive to tall plants in Mendel’s experiments.
  • When crossing tall and short plants, the F1 generation exhibits the tall phenotype, showing that tallness is the dominant trait.

The correct answer is A, B, and AB.

Key Points

• Blood is a body fluid.
• ABO blood grouping was given by Karl Landsteiner.
• The parent's blood group is AB.
• The blood group proteins are present in the 'I ' gene.
• The genotype of a parent is IA IB.

• From the punnet square, we can see that,
• The Blood group can be A, AB, and B.
• The blood group shows codominance interaction.
• A and B are codominant over the O blood group.
• IAIA = A blood group as here only A  allele is present on the I gene.
• IAIB= AB blood group as here A and B allele is present on the I gene.
• IBIB=B blood group as here B allele is present on the I gene.
• If the blood group of both parents is AB, then the possible blood group of their children will be A, B, and AB.

Additional Information

The correct answer is 1: 1.

Key Points

• '​Pure' plants refer to the homozygous condition in plants and 'hybrid' refers to the heterozygous plants.
• Homozygous - It is the condition in which the pair of alleles determining a phenotype is identical, either both dominant (TT) or both recessive (tt).
• Heterozygous - It is the condition where 2 different types of alleles are present, one dominant and one recessive (Tt).
• When a pure tall plant (TT) is crossed with a pure short plant (tt), the F1 generation produces heterozygous tall (Tt) plants.
• Upon selfing the F1 generation, that is, crossing two heterozygous tall plants, the following numbers of the F2 generation are obtained phenotypically:
  • Three tall plants and one short plant
• Whereas, genotypically, the following ratio is obtained:
  • One pure tall plant, two heterozygous tall plants, and one pure short plant.
• Therefore, considering the genotype, the ratio of pure tall plants to pure short plants in the F2 generation is 1:1. Hence, Option 1 is correct.

Mistake Points

• Please note here that the question asks about the ratio of "pure" tall plants to short plants in F2 generation.
• The usual ratio of 3:1 is for "all" tall plants to short plants.
• Pure Tall plants : Hybrid Tall plants : Short/Dwarf plants = TT : Tt : tt = 1:2:1
• Therefore, Pure tall : Pure short = 1:1

The correct answer is Option 2.
 Key Points

• In Mendel's experiment, The F1 generation results from the cross-pollination of two-parent (P) plants and contains all purple flowers. The F2 generation results from the Self-pollination of F1 plants and contains 75% purple flowers and 25% white flowers. (PHENOTYPE).
• The GENOTYPE was 25% pure purple flower, 50% hybrid purple flower, and 25% pure white flower.  
• Through this experiment, Mendel has concluded the Law of Segregation,
• "During the formation of gamete, each gene separates from each other so that each gamete carries only one allele for each gene."

Explanation-
PHENOTYPIC RATIO - 3:1
GENOTYPIC RATIO -  1:2:1

Additional Information

• On the basis of his experiments, Mendel has given three laws of Inheritance -
• Law of Dominance, Law of Segregation, Law of Independent Assortment.
• Mendel has selected 7 pairs of opposite characteristics of the Pea plant.
• The law of dominance is known as the First law of Inheritance. 
• In this law, each character is controlled by distinct units called factors (which are later known as Genes ), which occur in pairs. 
• If the pairs are heterozygous, one will always dominate the other.
• The Law of Independent Assortment states that Alleles for separate traits are passed independently of one another.

The correct answer is Pisum sativum.

Key Points

• Gregor Mendel, often called the father of genetics, used Pisum sativum, commonly known as pea plants, for his genetic experiments.
• His experiments involved cross-breeding pea plants with different traits to observe how traits were inherited.
• Mendel's choice of pea plants was due to their many distinct varieties, controlled mating, and short generation time, making them ideal for study.
• His findings on the inheritance of traits in pea plants led to the formulation of the laws of inheritance, including the concepts of dominant and recessive traits.

Additional Information

• Other plants mentioned such as Gossypium hirsutum (cotton), Triticum aestivum (wheat), and Oryza sativa (rice) are important crops but were not used by Mendel for his foundational genetic studies.
• Understanding Mendel's experiments and his development of the laws of inheritance is crucial for the study of both classical and modern genetics.

Key Points

 Gregor Mendel gave the Laws of Inheritance based on his experiments on Pisum sativum (garden pea):

• Law of Dominance -
  • It states that characters are controlled by discrete units called factors (alleles) which occur in pairs.
  • It also states that in a dissimilar pair of alleles, one of the alleles is expressed (dominant) over the other (recessive).
• Law of Segregation - 
  • It states that alleles do not show any blending and both parental characters are recovered in the F2 generation.
  • It also states that during gamete formation, alleles of a pair separate in such a way that one gamete receives only one of the two alleles of a pair.
  • It is also known as the Law of purity of gametes.
  • It can be proved with a monohybrid cross.
• Law of Independent Assortment -
  • It states that when 2 pairs of traits are combined in a hybrid, segregation of one pair is independent of the other pair.
  • It can be proved with a dihybrid cross.

Additional Information

•  Law of Natural Selection -
  • It was given by Charles Darwin.
  • It states that individuals with more favourable characters survive better and leave more progeny that again survives better and are hence selected by nature.

The correct answer is Gene

Key Points

• Gene is a basic unit of heredity and a sequence of nucleotides in DNA that encodes the synthesis of a gene product, either RNA or protein. 
• Thus, Gene is the basic unit of inheritance.
• The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. 
• These genes make up different DNA sequences called genotypes.

Concept:

• Genes are hereditary markers from which derive various characteristics like skin colour, height, etc.
• Each DNA molecule consists of sequences of Genes.
• Each gene is a particular set of instructions for specific functions.
• Each gene naturally consists of a sequence of nucleotides and base pairs.

Additional Information

The correct answer is YY x yy.

Concept:

Genetic cross:

• Gregor Johann Mendel, also known as the Father of Genetics, experimented on pea plants for seven years from 1856 to 1863.
• He studied 7 characters namely, plant height, flower colour, flower position, seed colour, seed shape, pod colour, and pod shape.  
• He studied the inheritance pattern by crossing two pure breeding lines for contrasting pairs of traits. 
• He came up with monohybrid and dihybrid crosses, where the inheritance of one and two characters was studied respectively. 

Explanation:

Monohybrid Cross between tall and dwarf pea plants:

• Mendel took purebred tall and dwarf pea plant varieties and cross-pollinated them.
• He observed that in the first (F1) generation only tall plants were grown.
• But on selfing the F1 generation, the dwarf trait reappeared. 
• He concluded that there is a factor that didn't express itself in the F1 generation while the other one did. 
• The concept of genes was not known at that time.
• He postulated that there are two factors one for each trait, and only one of them is able to express itself in heterozygous conditions.
• This factor is called the dominant factor and other that didn't express itself is called the recessive factor.  
• While writing the genotypes, the dominant factor/ gene is represented by a capital letter, while a small letter of the same alphabet is used to denote the recessive factor/ gene. 
• For example, the tall trait is expressed by TT but the dwarf trait by tt.

So, for a cross between yellow-coloured dominant seeds and green-coloured recessive seeds, YY × yy symbols will be used. 

Key Points

• Test cross -
  • It is a genetic cross of an organism with a dominant phenotype with an organism having recessive phenotype.
  • It is performed in order to determine the unknown genotype of an organism.
  • It helps us to know whether the dominant phenotype has a homozygous or heterozygous genotype.
• Homozygous - It is the condition in which the pair of alleles determining a phenotype is identical, either both dominant or both recessive.
• Heterozygous - It is the condition where 2 different types of alleles are present, one dominant and one recessive.
• Genotype - It is the allelic constitution of a gene determining a particular character.
• Phenotype - It is the expressed character.

• Mendel had chosen 7 traits for his experiments on garden pea, from which he observed these genetic crosses.
• Each of these traits had 2 distinct phenotypic characters - one dominant and one recessive.

Explanation:

• For example, let us take the trait of stem height with the phenotypes of tall and dwarf plants.
• The tall plants can be homozygous (TT) or heterozygous (Tt), while the dwarf plants are always homozygous recessive (tt).
• To determine the genotype of a tall plant, we would perform a test cross with a dwarf plant.
• The test cross may have 2 outcomes:
  • Case 1 - If the unknown tall plant is homozygous (TT), it would produce all tall plants (Tt).
  • Case 2 - If the unknown tall plant is heterozygous (Tt), would produce tall : dwarf plants in 1:1 ratio.

Additional Information

• Back cross -
  • It is the genetic cross between F1 generation and either of the parent.
  • It is performed to obtain an offspring with more phenotypic similarity with its parents.
  • It is mostly used for horticultural purposes and animal breeding.