Self-paced
P1
The characteristic smell or taste of a plant, to insects as well as to humans, depends on its chemical composition. ███████ █████████ ██████ ███████ ███ ██████████ ██ ████████ ███████████ ███████ ███ ██████████ ███
Intro topic ·
Two kinds of chemicals in plants: primary and secondary
Chemicals determine smell and taste of plants to insects and humans.
Primary substances ·
Stuff required for growth and functioning; found in all plants
Secondary substances ·
No known role in growth/functioning; give plants distinctive tastes and smells
P2
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Origin of secondary substances ·
Insects played major role
Causal mechanism 1 ·
Insects like some scents over others
Secondary substances result from mutations. Insects prefer some scents over others, which means the substances that produce those preferred scents are more likely to be passed on to future generations.
Causal mechanism 2 ·
Some substances produce stuff that helps defend against insects
Causal mechanism 3 ·
Some substances produce stuff that warns insects not to eat the plant
P3
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Competition between insects and plants ·
Insects evolve to respond to plants' defenses
Might evolve way to detoxify plant's poison or store the poison in an unharmful way, for example. Might evolve way to identify poisonous plants.
Passage Style
Phenomenon-hypothesis (RC)
Single position
10.
In the passage, the author █████████ ███████ ██████████ ██████ ██ █████ ██
a
provide information about ███ ██████ ████ ███ ██████████ █████████
This isn’t the purpose, because (A) ignores the context. The rest of the passage is about secondary substances and the development of secondary substances. So in describing primary substances and how they’re different from secondary substances, the author’s purpose relates to secondary substances. The author isn’t merely trying to teach us how plants grow and absorb nutrients. That purpose wouldn’t have any connection to the rest of the passage and its focus on secondary substances.
b
help explain what █████████ ██████████ ███
This best captures the purpose. The author tells us what primary substances do in order to help us understand what secondary substances don’t do. This is part of an explanation of secondary substances.
c
help distinguish between ███ ████ ████ ███████ ████ ████████ █████ █████████
The ways that insects have affected plant evolution aren’t brought up in P1 and don’t relate to the description of primary substances. So (C) can’t be the purpose of mentioning primary substances.
d
indicate the great █████████ ██ █████████ ████ █████ ██ ███████ ███████ ██ ██████
Although the author mentions several different primary substances, the author never characterizes these as showing a great diversity. Note that the author does say that secondary substances are a “diverse and multitudinous array of chemicals,” but she doesn’t say this with respect to primary substances. So (D) isn’t the purpose of the discussion of primary substances.
e
provide evidence of ███████ ██████████ ██ ███████
Nothing in P1 provides evidence of plants’ adaptation to insects. The evidence comes in P2.