Mendelian genetics

Question 1

What is Mendel’s first law of equal segregation?

Answer 1

Homologous chromosomes or two alleles of a gene segregate from each other equally

Question 2

What is Mendel’s second law of independent assortment?

Answer 2

Different chromosomes assort independently from each other. Ex. A has the same chance of lining with B and b

Question 3

What was known about inheritance prior to Mendel’s experiments with peas?

Answer 3

Traits were passed on from parents to offspring, how plant breeding worked, diseases could be inherited, cell theory, only reproductively successful parents passed on their traits

Question 4

What 4 things enabled Mendel to discover the mechanism of heredity?

Answer 4

He worked with true breeding lines, used traits only determined by alleles for one gene, chose a good model organism, carried out a large number of crosses and kept all records

Question 5

What are true breeding lines?

Answer 5

Lines that are homozygous in a trait of interest, either AA or aa. Aa is not true breeding

Question 6

Why were peas a good model organism?

Answer 6

Grew easily and quickly, had lots of genetic diversity, can both self pollinate or cross pollinate

Question 7

What are monohybrid crosses?

Answer 7

Crossing two individuals that are heterozygous for a trait of interest

Question 8

What did the F1 generation of a monohybrid cross show?

Answer 8

Shows which trait is dominant

Question 9

What did Mendel observe in the F1 generation in the monohybrid cross?

Answer 9

All the plants had the dominant phenotype

Question 10

What did Mendel observe in the F2 generation when the F1 generation was selfed?

Answer 10

The recessive trait reappeared, had a phenotypic ratio of 3:1

Question 11

What were the genotypes and phenotypes of the F1 and F2 generations in monohybrid crosses?

Answer 11

F1: all dominant, all Pp
F2: 3 dominant for every 1 recessive, 1 PP, 2 Pp, 1 pp

Question 12

What is a dominant trait?

Answer 12

The phenotype that shows if the allele is in a heterozygous gene pair

Question 13

What is a recessive trait?

Answer 13

The phenotype that doesn’t show if the allele is in a heterozygous pair

Question 14

What is a testcross?

Answer 14

Crossing an organism of an unknown genotype with a homozygous recessive tester

Question 15

What is a dihybrid cross?

Answer 15

A cross between 2 individuals heterozygous for two different traits

Question 16

What were Mendel’s observations with a dihybrid cross?

Answer 16

All the F1 had a dominant phenotype. The F2 generation had 9 dominant/dominant, 3 dominant/recessive, 3 recessive/dominant, 1 recessive/recessive