Plant Chemistry Quiz

Unless they’re food on the table or part of captivating scenery, plants are under-appreciated. Even fewer people care for the intricacy of their biochemistry or realize how in tune they are with their environment. Here’s a short quiz written for nonspecialists who nevertheless have a curiosity for what goes on below the surface of leaves and flowers. Especially since there are no student grades at stake, if one can anesthetize the ego, one can trade in a little time for precious botanical knowledge. By clicking on “explanation” below each question, you will find the answer with more insight into the topic.

1.  Which of these compounds do plants assemble “from scratch”—- in other words just from water, carbon dioxide and ions from the soil?

(A) glucose

(B) amino acids

(C) flavonoids (used as a “sunscreen”, pigments and have many other functions)

(D) defence compounds

(E) all of the above

(F) none of the above


2. What compound, found in willow bark, can be reacted with acetic anhydride in the presence of mineral acid to make aspirin?

(A) paracetamol
(B) ibuprofen

(C) salicylic acid

(D) caffeine


3. Which of these plants, a member of the buttercup family, has one of the most poisonous roots due to 3 nasty alkaloids(aconitine, mesaconitine & jesaconitine)?

(A) monkshood (B) mountain ash

(C) opium poppy

(D) milkweed


4. Fermentation often occurs inside a cantaloupe. Small volumes of which alcohols are produced?

(A) butanol and ethanol

(B) ethanol and benzyl alcohol

(C) methanol and benzyl alcohol

(D) methanol and butanol



5. The glandular hairs of wormwood leaves, Artemisia annua , yields the important drug artemisinin? What disease does the drug treat?

(A) malaria (B) sleeping sickness

(C) elephantiasis

(D) ebola


6. At least 400 compounds contribute to its beautiful scent including these:

Which flower are we referring to? (look carefully at the structures!)

(A) iris

(B) peony

(C) rose

(D) violet


7. Compounds like tomatin make the leaves poisonous to many insects. Solanine makes the leaves of related plants also toxic to many insects. Compared to tomatin, solanine is considerably more toxic to humans. What plants are we referring to, respectively?

(A) tomatoes and red peppers

(B) tomatoes and potatoes/eggplant

(C) potaotes and red peppers

(D )potatoes or eggplant/ tomatoes


8. What common substance is crucial to photosynthesis because it is the ultimate source of electrons, which must be returned to excited chlorophyll?

(A) potash fertilizer

(B) nitrate fertilizer

(C) water

(D) carbon dioxide


9. Which plant’s roots provides sugars and leghemoglobin to bacteria in exchange for ammonium ion?

(A) bean

(B) radish

(C) tomato

(D) lettuce


10. What are the most common elements in a plant?

(A) N, C, H, O, P and Mn

(B) N, C, H, O and S

(C) C, H, O, N and Mg

(D) C, H, O, P, N and K


whitespace#Answer1 –E–Plants don’t eat. They only absorb water and ions from the soil and carbon dioxide from the air. With these substances they produce not only glucose but all of the amino acids, nucleic acids and secondary compounds that they require.

whitespace#Answer2 –C– The first two are tylenol and advil. Salicylic acid, upon reacting with acetic anhydride in the presence of a catalyst(acid), will create acetylsalicylic acid, which is aspirin.

Caffeine is an alkaloid, whose structure is unrelated to aspirin.

whitespace#Answer3 –A– If one is familiar with the buttercup family(Ranunculacae), one realizes from the shape of the leaves of the four plants shown, that only the monkshood is related to the buttercup. The opium poppy produces morphine in its pod. The fruits of the mountain ash in large amounts can cause stomach irritation and pain, vomiting, queasiness, diarrhea, kidney damage, and other side effects. Finally the milkweed concentrates its poison in the above ground parts.

whitespace#Answer4 –B– Technically an alcohol is any compound in which the oxygen atom is sandwiched between a hydrogen and a carbon atom from a hydrocarbon group. Cantaloupe produces small amounts of ethanol (CH3CH2OH), the same alcohol produced from fermentation of apples, hops and grapes to make cider, beer and wine. According to this source benzyl alcohol (C6H5CH2OH) can also be produced.  The latter is not at all toxic in low doses and has a sweet, pleasant odor. Not surprisingly, it is also found in hyacinth and jasmine flowers.

whitespace#Answer5 –A– Notice that malaria and one form of sleeping sickness are directly caused by protozoans(Plasmodium and Trypanosoma respectively), but in both cases the microorganism needs a vector, another organism that carries it from one victim to the next. Elephantiasis has no vector, and ebola is the only one out of the four above diseases to be caused by a virus.

From Center of Disease Control
From Center of Disease Control


For more on the use of artemesin and its “green” extraction, see this Periodic Table Video: artemisinin , which is sparingly produced by Artemisia annua and also difficult and expensive to artificially make from scratch.

whitespace#Answer6 –C– The name of the first compound gives it away, cis-rose

whitespace#Answer7 –B–
The name tomatin gives away the 1st part of the answer. Potatoes and eggplant leaves are toxic to humans becuase of solanine. Those of tomatoes are free of solanine and since tomato leaves have low concentrations of a much milder alkaloid, they are not toxic, contrary to popular belief. In fact tomatin is also found in green tomatoes.

whitespace#Answer8 –C–
Plants need water for a variety of reasons but especially to release electrons after sunlight ejects electrons from the photosystems of chloroplasts. Oxygen is produced when water dissociates, and the hydrogen ions that are also released set up a +/- gradient and thus a voltage that provides the chloroplast with the energy it needs to incorporate carbon dioxide.

whitespace#Answer9 –A–
From the list only the bean is a legume, which thanks to mutualism, can get ammonium ion from Rhizobium bacteria, which use nitrogen from the air to produce it.

whitespace#Answer10 –D– Along with N, C, H, O, and P,  sulfur is one of the six most common elements of life. Sulfur is part of four amino acids and is also key to many biochemical reactions. Having said that, S only makes up 0.1% of dry plant matter. From recalling the components of industrial fertilizer (N-P-K) one could correctly surmise that potassium(K) would be more common than sulfur in plants. And that would be correct. It makes just under 1% of plant dry matter, on average. Plants need potassium ion for proper transcription of many genes and to control the activity of many enzymes.

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