Biomogy
Formative Assessment #10
SC.912.L. 15.8
7. Scientists, investigating scientific explanations of the origins of life on Earth, have used
evidence to support a hypothesis that organic compounds originated in space, and first
arrived on Earth on a meteorite. This hypothesis is based on the discovery of a meteorite
that landed in Australia that contains traces of many organic compounds.
Which of the following best summarizes how additional investigations might affect this
hypothesis?
A. This old hypothesis cannot be further investigated.
B. Added evidence might allow this hypothesis to become a scientific law.
C. Over time, the hypothesis will change to a theory, and then to a scientific law.
D. This hypothesis, if supported by the work of many scientists over time, might lead to
the formation of a scientific theory.

answer; ///i believe its: ///(embolus);

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.