Fundamentals of Genetics - Weebly

Workbook AnswersTopic 1.2

NEL Answers Topic 1. 2 1

Fundamentals of Genetics

1. a) probabilityb) F1 generation

c) F2 generation

d) phenotypic ratio

e) genotypic ratio

f) homozygous

g) homozygous dominant

h) homozygous recessive

i) recessive

2. A Punnett square is a grid that shows the genotype of the parents and the possible genotypes of the offspring. It is used to determine the probability of inheriting a trait.

3.

RrRRR

r Rr rr

R r

b. homozygous dominant

a. dominant allele

c. recessive allele

f. offspring

d. heterozygous e. homozygous recessive

4. The Punnett square shows a monohybrid cross.

5. a) Rrb) round seeds

c) 75% round seeds

d) 25% wrinkled seeds

e) 1RR:2Rr:1rr

f) 3 round seeds:1 wrinkled seed

Dominant and Recessive

1. A recessive trait is expressed when two recessive alleles are present.

2. A dominant trait is expressed when one or two dominant alleles are present.

3. a) FF b) Ff c) ff

Answers UNIT 1 TOPIC 2.indd 1 18-07-27 12:48 PM


2 Answers Topic 1. 2 NEL

4. a) 100% TT; 0% Tt; 0% tt 100% tall stem; 0% short stem

c) 50% PP; 50% Pp; 0% pp 100% purple flower; 0% white flower

5. a) 0% EE; 50% Ee; 50% eeb) 50% long eyelashes; 50% short eyelashes

TT × TT

T TT

T

T TT

TT

T

TT

Yy × Yy

Y YY

Y

y Yy

Yy

y

yy

b) 25% YY; 50% Yy; 25% yy 75% yellow seed; 25% green seed

d) 0% RR; 0% Rr; 100% rr 0% round seed; 100% wrinkled seed

PP × Pp

P PP

P

P PP

Pp

p

Pp

rr × rr

r rr

r

r rr

rr

r

rr

E Ee

e

e ee

Ee

e

ee




6 a) The dominant form of the gene is hairy toes (H).b)

Pair 1: Hh and Hh Pair 2: Hh and hh Pair 3: HH and HH or HH and Hh

Pair 3

H HH

H

h Hh

HH

H

Hh

Pair 2

H Hh

h

h hh

Hh

h

hh

Pair 3

H HH

H

H HH

HH

H

HH

Pair 1

H HH

H

h Hh

Hh

h

hh




Codominance and Incomplete Dominance

1. Complete Dominance: Genotype = Rr and Phenotype = redIncomplete Dominance: Genotype = FRFW and Phenotype = pinkCodominance: Genotype = FRFW and Phenotype = red and white

2. a) 25% HRHR; 50% HRHW; 25% HWHW

b) 25% red; 50% roan; 25% white

c) Genotypic Ratio: 1:2:1

3. a) 0% FBFB; 100% FBFW; 0% FWFW

b) 0% black; 100% checkered; 0% white

4. Phenotypes of children: 50% Type A Blood; 50% Type B Blood; 0% Type AB Blood; 0% Type O Blood

5. Probability of Type O blood: 0%

6. Genotypes of the parents: AO and BO

Complete Dominance

Genotype: RRPhenotype: red

Genotype: RrPhenotype: red

Genotype: rrPhenotype: white

Incomplete Dominance

Genotype: FRFR

Phenotype: redGenotype: FRFW

Phenotype: pinkGenotype: FWFW

Phenotype: white

Codominance

Genotype: FRFR

Phenotype: redGenotype: FRFW

Phenotype: red and whiteGenotype: FWFW

Phenotype: white

d) Phenotypic Ratio: 1:2:1e) 3 red, 6 roan, 3 white




7. a) Genotypes of the parents: FRFR and FWFW

b) Genotype of the pink flowers: FRFW

c) Genotypes of the F2 generation: 25% FRFR, 50% FRFW, and 25% FWFW

Phenotypes of the F2 generation: 25% red, 50% pink, and 25% white

8. Possible genotypes: 50% HBHW and 50% HWHW

9. Cross 1: purple flower × blue flower (FRFB × FBFB)

Cross 2: purple flower × purple flower (FRFB × FRFB)

Sex-Linked Traits

1. A sex-linked trait is a characteristic controlled by genes located on the sex chromosomes.

2. a) XhYb) XhXh

c) XHY

d) XHXh

e) XHXH

3. a) 25% XHXH; 25% XHXh; 0% XhXh; 25% XHY; 25% XhYb) 25% hemophiliac; 75% normal blood clotting ability

4. Probability of child with vision deficiency: 0%

5. Probability of child with vision deficiency: 25%

6. a) The genotypes of the parents are XDXd and XDY.b) 25%




Genetics

Section of the Text Main TopicWhat the Text Says about the

Main Topic Supporting Details

Page 26, Statement 1 Trait “Passing of traits from parents to off spring.”

A male gamete combines with a female gamete and produces off spring.

Page 27, Paragraph 1,numbered list

Mendel's experiment "Mendel bred true-breeding purple-fl owered plants with true-breeding white-fl owered plants."

All fi rst generation off spring were purple.All second generation off spring had purple:white ratio of 3:1.

Page 27, Paragraph 2,Statements 1–3

Mendel's explanation "Each plant had two factors for each trait.Each parent donates one of these factors. One factor may dominate."

Observed same results for other traits such as seed colour, seed shape, and stem length.Traits disappeared in F1 plants but reappeared in F2 plants.

Page 28,Paragraph 4,Statements 3–6

dominant and recessive alleles

"Alleles can be dominant or recessive."

A dominant trait is observed if there are one or two dominant alleles.A recessive trait is observed only if there are two recessive alleles.


phenotype and genotype

"Phenotype is the physical expression of an organism's trait. Genotype is the specifi c combination of alleles it has for a trait."

Two identical alleles: homozygousTwo dominant alleles: homozygous dominantTwo recessive alleles: homozygous recessiveTwo diff erent alleles: heterozygous


Punnett square "A Punnett square is another way to represent the inheritance of traits."

Represents monohybrid crosses.The grid shows possible genotypes of off spring based on genotypes of the parents.




1.2 Assessment

1. H

2. A

3. B

4. F

5. E

6. I

7. G

8. D

9. C

10. C

11. C

12. C

13. A

14. B

15. B

16. D

17. D

18. C

19. C

20. D

21. D

22. B

23. B

24. C

25. Complete Dominance

Codominance

Inco

mplet

e Do

mina

nce

Sex

Linka

ge

Patterns of Inheritance

- one allele is dominant and will mask the recessive allele

- heterozygote expresses the same phenotype as the homozygous dominant individual

- e.g., traits in pea plants

- female can be a carrier

- e.g., colour vision deficiency, hemophilia

- trait is controlled by a gene on the sex chromosome

- none of the alleles for a gene is dominant over the other, but contribute equally to the phenotype

- e.g., roan coloration in cattle and horses

- heterozygote expresses both phenotypes

- two alleles for a gene are neither dominant nor obvious

- e.g., four o’clock flowers, snapdragon

- heterozygote expresses an intermediate phenotype


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