Sex-Linked vs. Autosomal

In fruit flies, eye color is a sex linked trait. Red (R) is dominant to white (r). What is the sex and eye color of flies with the following genotype: X ^R X ^r ?

• male with white eyes

• female with red eyes

• male with red eyes

• female with white eyes

Tags

NGSS.HS-LS3-1

In fruit flies, eye color is a sex linked trait. Red (R) is dominant to white (r). What is the sex and eye color of flies with the following genotype: X ^R Y ?

• male with white eyes

• female with white eyes

• male with red eyes

• female with red eyes

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

What are the genotypes of these flies:

white eyed, male ?

• X ^R X ^r

• X ^R X ^R

• X^r X ^r

• X ^r Y

• X^R Y

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

What are the genotypes of these flies:

white eyed, female ?

• X ^R X ^r

• X ^R X ^R

• X^r X ^r

• X ^r Y

• X ^R Y

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

What are the genotypes of these flies:

red eyed female (heterozygous) ?

• X ^R X ^r

• X ^R X ^R

• X^r X ^r

• X ^r Y

• X ^R Y

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

X^B=Normal Allele

X^b=Colorblind Allele

Cross an X^BX^b mother with an X^bY father.

What proportion/percent of the male children are colorblind?

• 100%

• 75%

• 50%

• 25%

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

NGSS.HS-LS3-3

X^B=Normal Allele

X^b=Colorblind Allele

Cross an X^BX^B mother with an X^bY father.

What proportion/percent of the male children are colorblind?

• 100%

• 75%

• 25%

• 0%

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

Males are more likely to suffer from a sex-linked disease or disorder because

• males are the weaker sex
• males have less DNA
• males have 1 X chromosome, so the disorder is more likely to be expressed

Tags

NGSS.HS-LS3-2

Why is the gene for a disease or disorder more likely to be found on the X chromosome than Y?

• The X chromosome has many more genes
• The Y chromosome has many more genes

Tags

NGSS.HS-LS3-1

When we say that a woman is a carrier for a genetic disease or disorder it means that

• she has 1 gene, but not the disorder
• she has 2 genes for the disorder
• she can pass the gene only to male children
• she can pass the gene only to female children

Tags

NGSS.HS-LS3-1