D 3.2: Inheritance

Question 1

What is the essential idea of inheritance?

Answer 1

The inheritance of genes follows patterns

Question 2

What are the inheritance patterns called?

Answer 2

According to Mendel, the “Mendellian Ratio”

Question 3

What were the previous theories on inheritance?

Answer 3

• Genetic blend or mix of the traits of the parents

Question 4

Who was Gregor Mendel?

Answer 4

“The Father of Genetics” because he figured out the patterns in inheritance (genes!) via a pea plant experiment

Question 5

What did Gregor Mendel discover?

Answer 5

• Mendel found that characteristics were inherited in a predictable pattern
• All pea plants** in the first generation had the same characteristic as one of the parental plants**
• The offspring plants in the** second generation had characteristics of both parent plants in a 3:1 ratio**
• Without knowing it,** Mendel had discovered genes,** he referred to them as* ‘units of inheritance’*
  He also discovered that some genes are dominant and some genes are recessive
• Different forms of the same gene are called alleles

Question 6

Why do some plants not follow the phenotypic ratio “3:1” proposed by Mendel?

Answer 6

-** Incomplete Dominance:** In some plants, neither allele is fully dominant, resulting in a blending of traits. For example, a red-flowered plant crossed with a white-flowered plant might produce offspring with pink flowers, leading to a 1:2:1 phenotypic ratio instead of the expected 3:1.

• Codominance: In codominance, both alleles are expressed equally in the phenotype. For instance, in certain plants, if a red and white flowered plant are crossed, the offspring may show both red and white petals.