Self-study
Some types of organisms originated through endosymbiosis, the engulfing of one organism by another so that a part of the former becomes a functioning part of the latter. ██ ███████ ████████████ █ █████████ ████ ████████ ███ ███ █████████ █ ████ ████████ ███ ████ ██████████ ██████ █ █████ █████ ██ █ ███████████████████ ███ ████████ ██ █ ██████████ ████ ████ ████ █████ ██ ███ ███ ██ ████ ████████████ ███ ███ █████ ██████ ██ ████ ████ █ ██████ ███████ ██ ████ ████ ██ ███ ███████████ ████ ███ ███ ███████ ██ ██ ████████ ██████████ ████████
Summary
Organisms can be created through endosymbiosis, which is when organism A absorbs organism B, so organism B becomes part of organism A. We’ve also learned that a particular plant, “C,” contains a strange nucleomorph. Nucleomorphs are similar to cell nuclei, and contain DNA. The nucleomorph in plant C is strange because its DNA has two copies of a certain gene, which we would only expect if the nucleomorph had originally been an absorbed organism’s nucleus.
Strongly Supported Conclusions
The facts above strongly support the conclusion that the nucleomorph in plant C was originally an organism that was absorbed, meaning that plant C is a product of endosymbiosis.
22.
Which one of the following ██ ████ ████████ █████████ ██ ███ ███████████ ██████
a
Only organisms of █████ ████ ██████████ ███████ █████████████ ███████ █████████████
This is not supported. The stimulus doesn’t reveal much about where nucleomorphs come from. We can infer that the nucleomorph in plant C comes from endosymbiosis based on the facts given, but that doesn’t tell us about the origins of other nucleomorphs.
b
A nucleomorph within ███ ██████████████████ █████ ███ ██ ███ ███████ ████████ ██ ████ █████ █████████
This is not supported. We know that the nucleomorph in plant C contains some DNA, but we definitely don’t have enough information to say that the DNA is a full copy of another organism’s genetic material.
c
Nucleomorphs originated when ██ ████████ █████████████████ ████████ █ ███████████████████
This is anti-supported. From the facts, we know that plant C itself contains at least one nucleomorph, so it wouldn’t make sense for nucleomorphs to originate from plant C getting absorbed. For that to work, plant C would have to absorb itself, which is far-fetched.
d
Two organisms will ███ ███████ █████████████ ██████ ██ █████ ███ ██ ████ ████████ █ ████████████
This is not supported. The stimulus doesn’t suggest much about the relationship between endosymbiosis and nucleomorphs. We definitely can’t say that an organism already containing a nucleomorph is necessary for endosymbiosis to occur.
e
Chlorarachniophytes emerged as ███ ██████ ██ ███ █████████ ██████ █████████ ██████████████
This is strongly supported. The stimulus strongly implies that the nucleomorph within plant C used to be another organism that was absorbed, and we know that endosymbiosis is the name for that process. Thus, plant C probably comes from endosymbiosis.