Question

Learning Task 2: Read the handout about exploring snapdragon. Answer the
snapdragons which does not follow Mendel's Law of Dominance
guide questions in your notebook.
Handout: Exploring Snapdragons
In this activity you will investigate the genetic trait of a flower color in
Recalling Mendel's Law of Dominance, one allele can mask the expression
of another allele when they are joint together
. Therefore, if a person has a hete-
Tozygous genotype (i.e. one dominant allele and one recessive allele), he/she will
show the dominant phenotype (i.e. physical trait).
In snapdragons, there are two alleles for flower color - one coding for red
color and one coding for white color. When purebred red plants and purebred
white plants are crossed, the resulting offspring (i.e. the F1 generation) are all
pink. When the pink offspring are crossed to create a third generation (i.e. the
F2 generation), 25% of the offspring are red, 50% are pink, and 25% are
white. These results are summarized in the next page.​

Answer 1

Answer:

1.That genes come in pairs and are inherited as distinct units, one from each parent. Offspring therefore inherit one genetic allele from each parent when sex cells unite in fertilization.

2.The two alleles are red (R) and white (R').  

3.Non-Mendelian inheritance is any pattern of inheritance in which traits do not segregate in accordance with Mendel's laws.

Explanation:

Examples of non-mendelian

• Incomplete dominance.

• Co-dominance.

• Genetic linkage.

• Multiple alleles.

• Epistasis.

• Sex-linked inheritance.

• Extranuclear inheritance.

•Polygenic traits.

Answer 2

Answer:

Snapdragons doesn't follow Mendel's Law of Dominance instead they are following "incomplete dominance" which is a type of a non - mendelian inheritance pattern/ gene interaction.

Explanation:

• RR- pure breed red plants

R'R'- pure breed white plants

F1 progeny- heterozygous genotype RR'(according to Law of Dominance when a dominant allele is present it will dominates and mask the expression of recessive allele.) But all the F1 progenies were pink(meaning there is neither of Dominance of phenotypes present, hence showing a completely different coloured plant).

• This happens because the two alleles i.e red and white are partially dominant over each other and showing a blending of character as an outcome of phenotype of progeny.
• That's why in the F2 generation, 25% (RR) of the offspring are red, 50%(RR') are pink, and 25%(R'R') are white.

• There are other deviations from Mendelian Inheritance Pattern such as:

1. Co- Dominance: In this pattern of inheritance, both of the alleles express equally and together. Their effect is independent on each other. Example: Human Blood group. Shouldn't be confused with incomplete Dominance.
2. Multiple Allelism: When multiple forms of gene occupy same locus on a chromosome. Example: Eye colour in Drosophila.