Self-study
In an experiment, scientists changed a single gene in cloned flies of a certain species. █████ ██████ █████ ██████ ███ ███ █████ ████ ████ █████ ███████████ ███████ ████ ██████ ██████ ████████ ████ ██████████ █████████ █████████ █████ ███ ██████ ███████ █████ ██████████ ████ █████ ████ █████ ██ ████ ███████ ███████ ███████████ ██████ ████ ████ ████ ██████ ██ ████ █████
Summary
The author concludes that flies of a certain species flies lacking ultraviolet vision must have some damage to a particular gene. His reasoning is that flies who don’t have this gene lack ultraviolet vision.
Notable Assumptions
The author’s conclusion is about all flies of a certain species who lack ultraviolet vision. But we don’t know that all flies who lack UV vision lack this particular gene. We only know that flies who lack this gene also lack UV vision. What if other flies lack UV vision because of exposure to certain light or ocular injuries? There would then be causes of fly UV blindness that weren’t related to this gene.
Consequently, the author must assume that there are no potential causes of UV blindness in flies of this species except a problem with this particular gene.
10.
Which one of the following ██ ██ ██████████ ████████ ██ ███ █████████
a
The relationship between █████ ███ ██████ ██ █████ ██ ████ ███████████
This assumption is too strong to be necessary. Some understanding of the relationship may be necessary for the argument. But it doesn’t have to be an especially strong understanding.
b
No other gene ██ ███ █████ ██ ███ ██████████ ██ ████████ ███ ███ █████████ ██ ███ ███████████ ██████ ██████
Negated, this is: there is another gene required for the formation of the UV vision cells. If so, a problem with that gene, instead of the gene the author refers to, could lead to UV blindness in some cases. That would contradict the author’s argument, so he must assume (B) is true.
Note that this is a subset of the broader necessary assumption that there are no other potential causes of UV blindness in this species of fly.
c
Ultraviolet vision is █ █████ █████ ██ ███ ███████ ██ ██████
The scientist is only considering one species of fly, so the traits of other species are irrelevant.
d
The gene change ███ ██ ██████ ██ ███ █████ █████ ████ ███ ████ ██ ███████████ ██████ ██████
This is too strong to be necessary for the argument. Negated, this is: the gene change had an effect on the flies other than the lack of UV vision cells. That effect wouldn’t have to be relevant to UV vision, so this doesn’t contradict the author’s argument.
e
Ultraviolet vision is ██ ███████████████ ██████████ █████ ██ ███ ███████ ██ █████ ██ ███ ███████████
Since the author’s goal is conclude that UV blindness has a genetic cause, he would definitely not need to assume that it has environmental influences.