Heredity

Question 1

Pure dominant genotype:

Answer 1

BB

Question 2

Pure recessive genotype:

Answer 2

bb

Question 3

Hybrid genotype:

Answer 3

Bb

Question 4

Heterozygous gene pair:

Answer 4

Bb

Question 5

Homozygous gene pair:

Answer 5

BB or bb

Question 6

Dominant allele:

Answer 6

B

Question 7

Recessive allele:

Answer 7

b

Question 8

Use a punnett square to cross these: one heterozygous parent with one homozygous recessive parent parents (use the letter E).

Answer 8

E e

e Ee ee

e Ee ee

Question 9

When a pure dominant trait is crossed with a pure recessive trait, Which trait will express itself in all of the offspring? Dominant or recessive? Give an example.

Answer 9

Dominant because dominant alleles cover the recessive & all offspring will have a heterozygous genotype

        E         E

e Ee Ee

e Ee Ee

Question 10

What type of genotype is necessary for a recessive trait to appear?

Answer 10

Pure recessive (bb)

Question 11

If a person is a carrier for a disease, but does not have the disease, how would you describe the condition of the alleles?

Answer 11

heterozygous/hybrid

Question 12

What is a gene?

Answer 12

A gene is a small section of DNA that carries a specific code for a trait.

Question 13

Complete the missing information in the punnett square. How would you describe the gene for each parent?

Answer 13

Parent 1: bb (pure/homozygous recessive)
Parent 2: Bb (hybrid/heterozygous)

      b          b

B Bb Bb

b bb bb

Question 14

Complete the punnett square. Tell the genotype and phenotype for the offspring in percentages.
(R = round & r = wrinkled)

Answer 14

R r

R RR Rr

r Rr rr

Geno: 25% RR, 50% Rr, 25% rr
Pheno: 75% round, 25% wrinkled

Question 15

Different forms of a gene are called:

Answer 15

alleles

Question 16

List the following in order form smallest to largest:

Chromosome, allele, nucleus, Nitrogen base pair (adenine & thymine), DNA

Answer 16

Nitrogen base pair
allele (gene)
DNA
chromosome
nucleus

Question 17

What is a pedigree used for?

Answer 17

To trace the inheritance of a specific trait in a family.

Question 18

Use the pedigree to answer the following questions

a. What do the squares represent?
b. What does it mean if the circle is half shaded?
c. How many females express the trait of color-blindness?
d. If the female from generation IV-6 marries a dominant male (non color blind), what is the chance of having a daughter with the disorder? A son with the disorder? (N = Normal & n = color blind)

Answer 18

a. male
b. carrier but does not express the recessive trait
c. 1
d. 0% chance for the daughter; 50% chance for the son

Question 19

What is the difference between genetic engineering and selective breeding?

Answer 19

Genetic engineering: the actual DNA is altered in some way by inserting a needed gene directly into a persons cells

Selective breeding: specific traits are selected in the parents in order to ensure they are passed to the offspring & the genes are not actually altered

Question 20

List some positive uses for selective breeding.

Answer 20

The traits can easily be predicted.

You can produce offspring that can serve a specific purpose

Question 21

List some benefits of genetic engineering and give specific examples:

Answer 21

Make medication and treat diseases: create bacterial cells that produce important human proteins such as insulin.

Cure human genetic disorders: use virus to deliver the good gene to cells in the lungs of someone with cystic fibrosis

Improve crops: Insert bacteria DNA into rice, wheat, and tomatoes to enable plants to survive in colder temps, poor soil conditions, and resist insect pests.

Question 22

What is the purpose of DNA in the nucleus of a cell?

Answer 22

To carry the codes that contain information about the proteins needed to form specific proteins needed to build certain traits that the organism can express.

Question 23

What is incomplete dominance? Give an example.

Answer 23

When both alleles express themselves as a blend and neither allele dominates the other allele.

Red flower (RR) is crossed with a white flower (WW) and all the offspring are pink (RW)

      W          W

R RW RW

R RW RW

Question 24

Based on the pedigree below, what can we determine about the phenotype of the offspring in the 3rd generation?

Answer 24

The child could be hybrid or pure dominant and will have attached ears.

Question 25

What is codominance? Give an example.

Answer 25

A type of inheritance in which BOTH traits are expressed. Example: A brown horse and a white horse produce a roan (brown and white) horse.