Sex-linked traits and reading a pedigree
Grade 9 Science Worksheet
Circle the best answer.
Ari fills an empty Punnett square for model parents XBXb and XBY. Which statement about the offspring is true?
- Half of the XY offspring have the trait, and no XX offspring do
- No XY offspring have the trait, because the X comes from the XY parent
- Half of the XX offspring have the trait, and no XY offspring do
- Half of the offspring have the trait, in both XX and XY
Bo fills an empty square for the X-linked eye color that Morgan studied in fruit flies, using model genotypes XWXw and XwY. Which list gives the eye colors?
- 3 red-eyed flies : 1 white-eyed fly
- 2 red-eyed females : 2 white-eyed males
- 2 red-eyed females : 1 red-eyed male : 1 white-eyed male
- 1 red-eyed female : 1 white-eyed female : 1 red-eyed male : 1 white-eyed male
Esme fills an empty square for model parents XBXB and XbY. Which statement is true?
- Half of the offspring have the trait and half are carriers
- The XX offspring have the trait, since the XY parent has it
- The XY offspring have the trait, because the X comes from the XY parent
- No offspring have the trait, but the XX offspring are carriers
Read this first
Model group of XY individuals, Northern European ancestry (model counts; rate from NIH MedlinePlus Genetics)
group number in model group about how many have the red-green color vision difference XY individuals 1,200 1 in 12 Kira reads a model group of 1,200 XY individuals. About how many are expected to have the red-green color vision difference?
- 14,400 individuals
- 100 individuals
- 1,188 individuals
- 6 individuals
Two model groups, Northern European ancestry (model counts; rates from NIH MedlinePlus Genetics)
group number in model group rate with the red-green color vision difference XY individuals (men) 2,400 1 in 12 XX individuals (women) 2,400 1 in 200 Luz reads two model groups. About how many more XY than XX individuals are expected to have the trait?
- 2,388 more
- 188 more
- 0 more
- 212 more
Genotype card (model)
genotype chromosomes XBXB XX XBXb XX XbXb XX XbY XY. XB is dominant to Xb Milo sorts model genotypes. Which genotype is a carrier of the Xb allele?
- XBXB (an XX individual with no Xb allele)
- XBXb (an XX individual with one Xb allele)
- XbY (an XY individual with one Xb allele)
- XbXb (an XX individual with two Xb alleles)
Genotype list (model)
genotype chromosomes XBXB XX XBXb XX XbXb XX XBY XY XbY XY. XB is dominant to Xb Pia reads a genotype list. Which choice holds every genotype that shows the red-green color vision difference?
- XbXb and XbY
- XbXb (the Y covers the Xb allele in XbY)
- XbY and XBY (both XY genotypes)
- XBXb, XbXb and XbY
Use this
a circle with no dot is not marked either way.
Ren reads a made-up pedigree. II-2 is a filled square. From which parent did II-2 receive the Xb allele?
- From neither, since neither parent has the trait
- From both I-1 and I-2 (the trait needs two Xb alleles)
- From I-2 (an XY child takes its X from the XX parent)
- From I-1 (an XY child takes its X from the XY parent)
Tala reads the same pedigree. II-1 is a circle with no dot, so II-1 is not marked either way. What is the chance that II-1 carries Xb?
Use the picture in question 8.
- 1 in 4
- 1 in 1
- 0
- 1 in 2
Use this
Pedigree of a made-up family for the red-green color vision difference (squares are XY individuals, circles are XX individuals, a filled symbol has the trait, a circle with a dot is a marked carrier; a circle with no dot is not marked either way).
Zee reads a made-up pedigree. II-1 is a filled circle. Which statement fits the pedigree?
- II-1 has two Xb alleles: one from I-1 and one from I-2
- II-1 has one Xb allele, and one is enough to show the trait
- II-1 is a carrier, since a filled circle marks a carrier
- II-1 has two Xb alleles, and both came from I-2