Questions for scientific method
circumference volume
trial #1 65.4 cm
trial #2 65.3 cm
trial #3 65.5 cm
average
volume vs. trial number
volume, cubic cm
trial number
1 2 3 4 5
0
1. look at the volume values. are the volume values larger or smaller than you expected?
explain your answer.
scientific method
table 1
4
apex learning: biology labs
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2. are the volume values similar to each other, or are they quite different? explain why you
see what you see. if they are similar, explain why. if they are different, also explain why.
3. does the volume increase with trial number, decrease with trial number, or stay about
the same? explain why you think the results are the way there are. there are many
possible reasons for the data trend you see. give some that you think are reasonable.
4. this method of measuring the volume of your lungs is probably not completely
accurate. what changes would you make if you did this type of experiment to make it
more accurate?
5. how would you modify the hypothesis and repeat the experiment for improved or more
complete results?

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.