10 use the following key to you complete the field study. new fabula creatures taxonomic key step physical feature classification 1 smooth skin go to 2 fur go to 3 2 one eye go to 4 two eyes go to 5 3 one eye go to 7 two eyes go to 8 4 arms and legs silkus monowrestle legs only silkus monosquirmus 5 arms and legs go to 6 legs only silkus duosquirmus 6 tail silkus tallyhas no tail silkus stretchilus 7 tail fuzzus tallywag no tail fuzzus feelzalot 8 two teeth go to 9 more than two teeth fuzzus chompilus 9 pointy fuzzus pointilus square fuzzus squarilus fill in the chart with each creature's scientific name based on your field study observations. creature scientific name 1 2 3 4 5 6 7 8

b is dominant over the allele for the white fur.

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.

yes

no

blue is scattered more than other colors because it travels as shorter, smaller waves. this is why we see a blue sky most of the time.