A Little Genetics Review

1. A pink elephant is mated with a blue oneand all the offspring are pink with bluespots! This is an example of

A. normal inheritanceB. codominanceC. incomplete domianceD. a sex-linked trait

1. A pink elephant is mated with a blue oneand all the offspring are pink with bluespots! This is an example of

A. normal inheritanceB. codominanceC. incomplete domianceD. a sex-linked trait

2. A dark gray chinchilla is crossed with alight gray chinchilla and there are lightgray offspring and dark gray offspring.This is because of

A. normal inheritance.B. codominance.C. incomplete dominance.D. sex-linked inheritance.

2. A dark gray chinchilla is crossed with alight gray chinchilla and there are lightgray offspring and dark grey offspring.This is because of

A. normal inheritance.B. codominance.C. incomplete dominance.D. sex-linked inheritance.

3. A normal woman and a normal man have fivechildren, 4 boys and one girl. The girl and one ofthe boys are normal, the other three boys haveflippitis (the uncontrolled flipping of channelswith the remote). Flippitis is caused by:

A. normal inheritance.B. codominance.C. incomplete dominance.D. sex-linked inheritance.

3. A normal woman and a normal man have fivechildren, 4 boys and one girl. The girl and one ofthe boys are normal, the other three boys haveflippitis (the uncontrolled flipping of channelswith the remote). Flippitis is caused by:

A. normal inheritance.B. codominance.C. incomplete dominance.D. sex-linked inheritance.

4. Back to the chinchillas … If one parent isdark gray and the other is light gray, whatpercentage of their offspring will be lightgray? How many will be dark gray?

A. 50% light gray; 50% dark grayB. 25% light gray; 75% dark grayC. 75% light gray; 25% dark gray

* How do you know?

4. Back to the chinchillas … If one parent is darkgray and the other is light gray, what percentageof their offspring will be light gray? How manywill be dark gray?

A. 50% light gray; 50% dark grayB. 25% light gray; 75% dark grayC. 75% light gray; 25% dark gray

* How do you know?

Here’s why…DD, Dd = dark gray dd = light gray

Dark gray X Light gray Dd dd

Geno: 2 Dd : 2 dd

Pheno: 2 Dark gray: 2 Light grayddDdd

ddDdd

dD

5. A normal man and a normal woman are planning to havea family but they are concerned because the man’sbrother has hemophilia (a disorder whose gene islocated on the X chromosome). There is no history of thedisease in the woman’s family. What are their chances ofhaving any children with the disorder?

A. 50%B. 25%C. 100%D. 0%

How do you know?

5. A normal man and a normal woman are planning to havea family but they are concerned because the man’sbrother has hemophilia (a disorder whose gene islocated on the X chromosome). There is no history of thedisease in the woman’s family. What are their chances ofhaving any children with the disorder?

A. 50%B. 25%C. 100%D. 0%

How do you know?

• Here’s whyNormal ♀ X Normal ♂

XNXN X XNY

Geno: 2 XNXN :2 XNY

Pheno: 2 normal ♀: 2 normal ♂XNYXNYY

XNXNXNXNXN

XNXN

6. More elephants…If two spotted elephantswere mated what types of offspring wouldyou expect and in what ratio?

A. 100% spottedB. 25% spotted; 50% blue; 25% pinkC. 50% pink; 50% blueD. 50% spotted; 25% pink; 25% blue

Be able to explain your answer.

6. More elephants…If two spotted elephantswere mated what types of offspring wouldyou expect and in what ratio?

A. 100% spottedB. 25% spotted; 50% blue; 25% pinkC. 50% pink; 50% blueD. 50% spotted; 25% pink; 25% blue

Be able to explain your answer.

Here’s why…EPEP = pink EPEB = spotted EBEB = blue

Spotted X Spotted EPEB EPEB

Geno: 1 EBEB: 2EBEP: 1EPEP

Pheno: 1 Blue: 2 Spotted: 1 Pink

EBEBEPEBEB

EPEBEPEPEP

EBEP