Mendelian Genetics 1

Question 1

Why were peas chosen?

Answer 1

Strict control over which plant mated with which
Each plant has both male and female reproductive organs
Can be self fertilised

Question 2

What were the 7 characteristics Mendel studied?

Answer 2

Flower colour
Seed colour
Seed shape
Pod colour
Pod shape
Flower position
Plant height

Question 3

Define character:

Answer 3

Heritable feature (physical feature)

Question 4

Define trait:

Answer 4

Each variant of a character

Question 5

What are the 5 key steps in the pea plant experiment?

Answer 5

1. Grow true breeding plants (colour) P generation
2. Cross true bred purple with true bred white
3. F1 generation produced - all purple (dominant factor)
4. F1 generation self fertilised
5. F2 generation had some white flowers 705:224 (3:1)

Question 6

What was Mendel’s 2 conclusions from his pea experiment?

Answer 6

1. an organism inherits 2 factors (alleles) for a characteristic
2. When the plant reproduces these 2 alleles segregate

Question 7

What is Mendel’s law of segregation? (3)

Answer 7

1. Each gamete gives one allele
2. Each offspring gets one allele from each parent
3. Random fusion during fertilisation

Question 8

Define a phenotype?

Answer 8

Physical description of trait

Question 9

Define a genotype:

Answer 9

Genetic makeup

Question 10

What are different alleles? (2)

Answer 10

1. Different versions of a gene

2. Vary in the sequence of nucleotide bases at specific locus of the gene

Question 11

What is Mendel’s law of independent assortment?

Answer 11

Genes get shuffled - these many combinations are one of the advantages of sexual reproduction

Question 12

What are examples of Mendelian traits in humans? (5)

Answer 12

Earlobe attachment (dominant)
Hitchhikers thumb (dominant)
Widow's peak (dominant)
Tongue rolling (dominant)
Mid digital hair (dominant)

Question 13

What is pedigree analysis?

Answer 13

Mapping traits onto a family tree

Question 14

What are examples of recessively inherited disorders? (3)

Answer 14

Cystic fibrosis, sickle cell anaemia, Tay Sachs disease

Question 15

What are examples of dominantly inherited disorders? (2)

Answer 15

Huntingtons disease, achondroplasia (dwarfism)