Gregor Mendel, often referred to as the "Father of Genetics," conducted experiments with pea plants to understand how traits are inherited. He worked with seven pairs of contrasting traits such as flower color, seed shape, and pod color. Mendel crossed pea plants with different traits and studied the inheritance patterns in their offspring. His work led to the formulation of two fundamental principles of inheritance: the Law of Segregation and the Law of Independent Assortment.
According to Mendel's Law of Segregation, during gamete formation, the two alleles of a gene:
Answer: C) Segregate randomly, resulting in the separation of alleles
Mendel's experiment with pea plants resulted in the F2 generation showing a phenotypic ratio of:
Answer: B) 3:1
If a pea plant with yellow seeds (Y) is crossed with a plant having green seeds (y), what would be the genotype of the F1 generation?
Answer: B) Yy
In Mendel's experiment, when he crossed two heterozygous plants (Yy) for seed color, the offspring showed a phenotypic ratio of:
Answer: B) 3 Yellow: 1 Green
Mendel’s Law of Independent Assortment states that the inheritance of one trait is independent of the inheritance of another trait, provided the genes for the traits are located on different chromosomes. This law was established after Mendel performed dihybrid crosses. For example, when he crossed plants that were heterozygous for two traits, seed color (Yellow/Green) and seed shape (Round/Wrinkled), he observed that the inheritance of seed color was independent of seed shape.
When Mendel crossed two pea plants that were heterozygous for two traits, seed color (Yy) and seed shape (Rr), the F2 generation showed a phenotypic ratio of:
Answer: A) 9:3:3:1
According to the Law of Independent Assortment, which of the following statements is true?
Answer: B) Genes located on different chromosomes assort independently during gamete formation
A plant with genotype YyRr is crossed with another plant with genotype YyRr. What is the probability of getting an offspring with the genotype YYRR?
Answer: A) 1/16
In the case of a dihybrid cross, how many different types of gametes can be produced by a parent with the genotype AaBb?
Answer: B) 4
While Mendel’s laws were foundational, later studies showed that genes located close together on the same chromosome tend to be inherited together. This phenomenon is called genetic linkage. However, during meiosis, a process called crossing over can occur, where homologous chromosomes exchange portions of their chromatids. This leads to genetic recombination and can break the linkage between genes, producing new combinations of alleles.
The phenomenon in which genes located close to each other on the same chromosome tend to be inherited together is called:
Answer: C) Genetic linkage
Which of the following events can result in the formation of new allele combinations in offspring?
Answer: C) Crossing over
If two genes are located very far apart on the same chromosome, what is likely to happen during meiosis?
Answer: D) They will undergo frequent recombination
A cross between two heterozygous individuals for two traits results in a 50% recombination frequency. This suggests that the genes involved:
Answer: D) Are located far apart on the same chromosome
In some cases, the inheritance of traits does not follow the classic Mendelian dominance-recessive pattern. Codominance occurs when both alleles in a heterozygous individual contribute equally and visibly to the phenotype. Incomplete dominance is when the heterozygous phenotype is an intermediate of the two homozygous phenotypes. An example of incomplete dominance can be seen in the inheritance of flower color in snapdragons, where crossing a red flower (RR) with a white flower (WW) results in pink flowers (RW).
In codominance, when a red cow (RR) is crossed with a white cow (WW), what will be the color of the offspring?
Answer: D) Roan (red and white patches)
In incomplete dominance, when a red flower (RR) is crossed with a white flower (WW), the offspring will be:
Answer: C) Pink
Which of the following is an example of incomplete dominance?
Answer: B) Flower color in snapdragons
In a cross between two pink snapdragons (RW), the F2 generation will show a phenotypic ratio of:
Answer: A) 1 Red: 2 Pink: 1 White
The inheritance of human blood groups follows the principles of multiple alleles, where more than two alleles are involved in determining the phenotype. The ABO blood group system is determined by three alleles: A, B, and O. A and B are dominant, while O is recessive. A person inherits one allele from each parent, and the combination of these alleles determines their blood type.
A person with blood type AB has which genotype?
Answer: B) AB
Which of the following blood group combinations could result in a child with blood group O?
Answer: B) AO × BO
If a man with blood type A and a woman with blood type B have a child, what is the probability that the child will have blood type AB?
Answer: B) 25%
Which of the following is true about the ABO blood group system?
Answer: B) The A and B alleles are codominant