Genetics + Germ Layers

Question 1

Law of segregation

Answer 1

During formation of gametes, two traits carried by each parent separate. Best shown in monohybrid cross: Tt x Tt

Question 2

Phenotype ratio of monohybrid cross

Answer 2

3T : 1t

Question 3

Genotype ratio of monohybrid cross

Answer 3

1TT : 2Tt : 1tt

Question 4

Law of independent assortment

Answer 4

During gamete formation, genes for one trait are not inherited with genes for another. Best shown by dihybrid cross: TtYy x TtYy

Question 5

Genotype ratio of dihybrid cross

Answer 5

9TY : 3Ty : 3tY : 1ty

Question 6

PKU

Answer 6

• Autosomal recessive
• Inability to break down an amino acid. Requires elimination of the amino acid from diet, or mental retardation will result

Question 7

Cystic fibrosis

Answer 7

• Autosomal recessive

- Buildup of fluid in lungs, digestive tract, etc.

Question 8

Tay-Sachs

Answer 8

• Autosomal recessive

- Onset early in life, lack enzymes to break down fats needed for brain

Question 9

Huntington’s

Answer 9

• Autosomal dominant

- Onset in middle age

Question 10

Klinefilter’s syndrome

Answer 10

XXY. Male with extra X chromosome

Question 11

Turner syndrome

Answer 11

Female, missing an X chromosome

Question 12

Ectoderm

Answer 12

Outer layer, becomes skin and nervous system

Question 13

Endoderm

Answer 13

Inner layer, becomes digestive system

Question 14

Mesoderm

Answer 14

Becomes blood, muscles, bones

Question 15

Diploblastic

Answer 15

2 germ layers: endoderm and ectoderm held together by mesoglea. E.g., porifera, cnidarians

Question 16

Triploblastic

Answer 16

3 germ layers