Principles of Inheritance and Variation (VSAQs)

Botany-2 | 9. Principles Of Inheritance And Variation – VSAQs:
Welcome to “VSAQs” in “Chapter 9: Principles Of Inheritance And Variation”. This page covers the most important VSAQs from previous exams. Use these concise answers to strengthen your understanding and get ready to do well in your final exams.

VSAQ-1 : What is the cross between the F1 progeny and the homozygous recessive parent called? How is it useful?

A test cross involves the mating of the F1 progeny (first-generation offspring) with a homozygous recessive parent. Its utility lies in determining the genotype of the F1 organism. By observing the phenotypic ratios of the resulting offspring, one can discern whether the F1 organism is homozygous dominant or heterozygous for a particular trait. This information is instrumental in elucidating the inheritance patterns of specific traits and uncovering the genetic composition of the test organism, aiding in the study of genetics and heredity.

VSAQ-2 : Do you think Mendel’s laws of inheritance would have been different if the characters that he chose were located on the same chromosome?

Yes, if the characters Mendel chose for his experiments were located on the same chromosome, his laws of inheritance would likely have been different. This is because genes situated on the same chromosome tend to be inherited together as a linked unit, which contradicts Mendel’s law of independent assortment. This law asserts that alleles of different genes segregate independently during gamete formation. The presence of genetic linkage would have altered the observed inheritance patterns, resulting in different outcomes and potentially leading to a revised understanding of inheritance principles.

VSAQ-3 : Who proposed the Chromosome theory of inheritance?

The Chromosome Theory of Inheritance was independently proposed by Walter Sutton and Theodor Boveri in the early 20th century. Their groundbreaking theory posited that chromosomes serve as carriers of genetic information, with genes occupying specific positions on these structures. This theory laid the groundwork for comprehending the relationship between genetics and the behavior of chromosomes during cellular division and the inheritance of traits.

VSAQ-4 : Define true breeding. Mention its significance.

True breeding, also called pure breeding, pertains to the breeding of organisms that consistently yield offspring with identical traits when self-pollinated or mated with other true-breeding individuals across numerous generations. The significance of true breeding lies in its pivotal role within genetics and breeding research. It enables the observation and examination of traits that demonstrate consistent inheritance patterns across generations, facilitating the identification and comprehension of the genetic underpinnings of these traits. True breeding serves as a foundational tool for establishing and elucidating patterns of inheritance in genetic studies.

VSAQ-5 : Explain the terms phenotype and genotype.

  1. Phenotype: The term phenotype describes the observable physical characteristics or traits of an individual organism. These traits encompass features such as color, size, shape, and any other visible attributes that can be externally assessed.
  2. Genotype: On the other hand, genotype refers to the genetic makeup of an individual. It encompasses the specific combination of genes inherited from the organism’s parents, determining the genetic basis for its traits and characteristics. The genotype represents the underlying genetic information that influences the development of the phenotype.

VSAQ-6 : What is point mutation? Give an example.

Point Mutation is a form of mutation characterized by the alteration of a single base pair within the DNA sequence.

Example: An instance of a point mutation is seen in sickle cell anemia, a genetic disorder resulting from a point mutation in the hemoglobin gene. This mutation leads to the production of abnormal red blood cells, causing various health complications.

VSAQ-7 : What is the genotype of wrinkled phenotype of pea seeds?

The genotype associated with the wrinkled phenotype of pea seeds is typically represented as “Rr.”

VSAQ-8 : What will be the phenotypic ratio in the offsprings obtained from the following crosses. 1)Aa x aa 2)AA x aa 3)Aa x Aa 4)Aa x AA

  1. Aa x aa – Phenotypic ratio: 1:1
  2. AA x aa – Phenotypic ratio: 1:0 (All offspring will have the same phenotype as the dominant parent, AA.)
  3. Aa x Aa – Phenotypic ratio: 3:1
  4. Aa x AA – Phenotypic ratio: 1:0 (All offspring will have the same phenotype as the dominant parent, AA.)