Lecture 23: The Nature of Inheritance & Mendel's Law

Question 1

Who is Johann Mendel?

Answer 1

• A monk who grew peas and noted that they had different traits and cross-polinated peas.
• He wasn’t recognised for his work in his lifetime

Question 2

The stamen of the flower is the _____ part and the carpal has the _____ part.

Answer 2

• Male

- Female

Question 3

The purple flower had _____ traits whereas the white flower had _____ traits.

Answer 3

• Dominant

- Recessive

Question 4

P stands for _____ and F (Filial) stands for _____.

Answer 4

• Parents

- Offspring

Question 5

What is the definition of atavism?

Answer 5

• Recessive genes skipping a generation
• Wrinkle + Smooth seeds = F1 Smooth Seeds
• F1 Smooth Seeds = F2 Wrinkle + Smooth Seeds
• (Monohybrid Cross)

Question 6

Mendel explained that….

Also it appears that individuals….

Answer 6

• Information is passed on from parents to offspring if information is packaged as discrete particles. Mendel called these factors. We now know them as genes.
• Have 2 copies of each gene, one inherited from mum, one from dad. Genes controlling a trait can differ - these different forms of a gene are called alleles

Question 7

Two different alleles for a gene in a chromosome is called:

Answer 7

• Heterozygous

Question 8

Punnett Squares!! Woo!!

Answer 8

• F gametes vs. M gametes
• Genotype : phenotype
• RR : smooth seeds
• Rr : smooth seeds
• rr : wrinkly seeds
• rR : smooth seeds

Question 9

The difference between phenotypes and genotypes:

Answer 9

• Phenotypes = appearance

- Genotype = what explains the appearance

Question 10

The test cross is used to find out the genotype of one of the seeds. How is this done?

Answer 10

• SS x ss (all come out smooth)

- Ss x ss (1:1 ratio)

Question 11

A child has red hair and their 3 siblings have brown hair. Assume that the dominant alleles are ‘B’ and the recessive alleles are ‘b’. What are the genotypes of the mother and father?

Answer 11

• Bb x Bb
• BB
• Bb
• bB
• bb

Question 12

What is the law of segregation?

Answer 12

• Genes segregate at meiosis so that each gamete contains only one of the two possessed by the parent

Question 13

A dihybrid cross gives the ratio:

Answer 13

• 9:3:3:1

Question 14

What is Mendel’s second Independent Assortment Law?

Answer 14

• Alleles of different genes assort independently during gamete formation