Questions & Answers
Browse all 25 questions from the
Organic Chemistry in the Natural World study set below.
Each question shows the correct answer — select a study format above to practice interactively.
1
Which polyunsaturated fatty acid, synthesized by marine algae and crucial for the health of marine ecosystems, is the primary source of Omega-3 in the oceanic food web?
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A
Docosahexaenoic acid (DHA)
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B
Oleic acid
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C
Palmitic acid
-
D
Stearic acid
2
The bioluminescence in fireflies (Photinus pyralis) is produced by the oxidation of which organic substrate catalyzed by the enzyme luciferase?
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A
Luciferin
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B
Aequorin
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C
Coelenterazine
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D
Chlorophyll
3
Which toxic organic compound is sequestered by the Monarch butterfly (Danaus plexippus) from milkweed plants to deter avian predators?
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A
Cardiac glycosides
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B
Alkaloid nicotine
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C
Reserpine
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D
Cyanogenic glycosides
4
What is the primary organic component of the adhesive silk produced by orb-weaver spiders, which provides its unique elasticity and strength?
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A
Fibroin proteins
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B
Chitin
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C
Keratin
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D
Cellulose
5
The characteristic 'petrichor' smell of rain hitting dry soil is primarily caused by the release of which volatile organic compound produced by Streptomyces bacteria?
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A
Geosmin
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B
Isoprene
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C
Limonene
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D
Benzene
6
Which aromatic organic compound, found in the defensive spray of certain millipedes, is derived from the metabolic pathway involving mandelonitrile?
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A
Hydrogen cyanide
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B
Formaldehyde
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C
Acetic acid
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D
Methanol
7
What class of organic pigments is responsible for the red, orange, and yellow coloration in flamingos, derived from their diet of crustaceans and algae?
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A
Carotenoids
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B
Anthocyanins
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C
Porphyrins
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D
Flavonoids
8
The venom of the Platypus contains defensin-like peptides, but the primary organic chemical class causing intense localized pain in their victims is not yet fully elucidated; however, which toxic organic family is commonly associated with animal venoms?
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A
Polypeptides
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B
Steroids
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C
Terpenes
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D
Phenols
9
Which organic compound, commonly found in the waxes of honeybees (Apis mellifera), is a long-chain ester formed from palmitic acid and melissyl alcohol?
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A
Myricyl palmitate
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B
Triacontanyl palmitate
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C
Cetyl palmitate
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D
Stearyl stearate
10
What volatile organic compound is emitted by plants in response to herbivore damage to attract parasitic wasps that prey on the attacking larvae?
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A
(Z)-3-hexenyl acetate
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B
Ethylene
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C
Methane
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D
Ethanol
11
Which polycyclic aromatic hydrocarbon is a known environmental pollutant that bioaccumulates in the fatty tissues of marine mammals like orcas?
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A
Benzo[a]pyrene
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B
Naphthalene
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C
Anthracene
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D
Phenanthrene
12
What organic molecule serves as the primary energy storage lipid in the seeds of oilseed crops like canola (Brassica napus)?
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A
Triacylglycerol
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B
Phospholipid
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C
Sphingolipid
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D
Wax ester
13
The defense mechanism of the bombardier beetle involves a violent reaction between hydroquinone and which other organic chemical?
-
A
Hydrogen peroxide
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B
Hydrochloric acid
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C
Sulfuric acid
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D
Nitric acid
14
Which alkaloid, found in the skin secretions of the poison dart frog (Phyllobates terribilis), is a potent voltage-gated sodium channel blocker?
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A
Batrachotoxin
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B
Strychnine
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C
Atropine
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D
Nicotine
15
What is the primary organic molecule in the cell walls of fungi, serving as a structural polysaccharide?
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A
Chitin
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B
Cellulose
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C
Amylose
-
D
Pectin
16
Which organic molecule, produced by many conifers, acts as a natural resin to seal wounds and deter boring insects?
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A
Terpenoid
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B
Steroid
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C
Amino acid
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D
Nucleotide
17
The blue color in certain deep-sea crustaceans is produced by a complex formed between a protein and which carotenoid molecule?
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A
Astaxanthin
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B
Lutein
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C
Zeaxanthin
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D
Beta-carotene
18
Which volatile organic compound is the primary pheromone component in the alarm signal released by many aphid species?
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A
(E)-beta-farnesene
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B
Geraniol
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C
Linalool
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D
Menthol
19
What is the main organic acid involved in the defensive secretion of the Formica genus of ants?
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A
Formic acid
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B
Acetic acid
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C
Butyric acid
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D
Lactic acid
20
Which organic sulfur compound is responsible for the characteristic pungent odor released by skunks (Mephitis mephitis)?
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A
(E)-2-butene-1-thiol
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B
Dimethyl sulfide
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C
Methanethiol
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D
Hydrogen sulfide
21
Which complex organic polymer, making up the woody tissue of plants, is formed by the dehydrogenative polymerization of coniferyl, coumaryl, and sinapyl alcohols?
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A
Lignin
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B
Cellulose
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C
Hemicellulose
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D
Suberin
22
Which organic compound is the primary nitrogenous waste product excreted by reptiles and birds to conserve water?
-
A
Uric acid
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B
Urea
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C
Ammonia
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D
Creatinine
23
The 'fishy' odor of decaying marine organisms is largely attributed to the presence of which organic amine?
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A
Trimethylamine
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B
Methylamine
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C
Ethylamine
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D
Propylamine
24
Which terpene is the primary component of citrus oil and serves as an effective natural insecticide?
-
A
Limonene
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B
Pinene
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C
Camphene
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D
Myrcene
25
Which organic molecule is the primary component of the structural protein 'silk fibroin' in silkworms?
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A
Glycine-serine-alanine polymer
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B
Glutamic acid polymer
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C
Proline-hydroxyproline polymer
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D
Lysine-arginine polymer
