Flavonoids Trivia Questions and Answers

1: What is another term for flavonoids derived from the Latin word for yellow?
A: Bioflavonoids
B: Polyphenolics
C: Anthocyanidins
D: Carotenoids
Correct Answer: A
Explanation: Flavonoids are also known as bioflavonoids, based on the Latin word “flavus,” which means yellow.

2: How many carbon atoms make up the general structure of a flavonoid skeleton?
A: 10
B: 12
C: 15
D: 18
Correct Answer: C
Explanation: The flavonoid structure consists of a 15-carbon skeleton, which can be abbreviated as C6-C3-C6.

3: Who discovered the additional components in citrus extracts that were effective against scurvy and referred to them as “Vitamin P”?
A: Albert Einstein
B: Louis Pasteur
C: Gregor Mendel
D: Albert Szent-Györgyi
Correct Answer: D
Explanation: Albert Szent-Györgyi, along with other scientists, identified these components in the 1930s.

4: Which ring in the flavonoid backbone typically shows a phloroglucinol substitution pattern?
A: Ring A
B: Ring B
C: Ring C
D: Ring D
Correct Answer: A
Explanation: The A ring often shows a phloroglucinol substitution pattern.

5: In which decade were bioflavonoids first termed due to their ketone-containing nature?
A: 1910s
B: 1920s
C: 1930s
D: 1960s
Correct Answer: C
Explanation: Bioflavonoids were first termed in the 1930s due to their ketone-containing nature, particularly anthoxanthins like flavones and flavonols.

6: Which class was not originally considered a vitamin, despite its name suggesting so?
A: Vitamin C
B: Vitamin D
C: Vitamin P
D: Vitamin B
Correct Answer: C
Explanation: Vitamin P (referring to bioflavonoids) was once thought to be a vitamin, but it does not meet the criteria for that classification.

7: How many naturally occurring flavonoids have been characterized from various plants?
A: 100
B: 500
C: 1000
D: 5000
Correct Answer: D
Explanation: Over 5000 naturally occurring flavonoids have been identified in various plants.

8: What are Rhizobia able to sense in the soil that triggers their symbiotic relationship with legumes?
A: Proteins
B: Sugars
C: Flavonoids
D: Nitrates
Correct Answer: C
Explanation: Rhizobia can sense flavonoids secreted by legume roots, triggering their symbiotic relationship.

9: Which subgroup of flavonoids is characterized by the skeleton of a 2-phenylchromenylium ion?
A: Anthoxanthins
B: Anthocyanidins
C: Flavanols
D: Isoflavones
Correct Answer: B
Explanation: Anthocyanidins use the flavylium ion skeleton, 2-phenylchromenylium.

10: Which food is a source of dietary anthocyanins?
A: Apples
B: Bananas
C: Blueberries
D: Carrots
Correct Answer: C
Explanation: Blueberries are known for their high content of dietary anthocyanins.

11: What is the main contributor of flavonoids in the diets of adults in the USA and EU?
A: Vegetables
B: Tea
C: Citrus fruits
D: Berries
Correct Answer: B
Explanation: Tea, particularly black, green, and oolong teas, is the primary source of flavonoids in adult diets in the USA and EU.

12: What subclass of flavonoids is hesperidin a glycoside of?
A: Anthocyanins
B: Flavonoids
C: Flavonols
D: Flavanones
Correct Answer: D
Explanation: Hesperidin is a glycoside of the flavanone called hesperetin.

13: Which cocoa content percentage is associated with high flavonoid content in dark chocolate?
A: 60%
B: 70%
C: 80%
D: 90%
Correct Answer: B
Explanation: Dark chocolate with a cocoa content of 70% or greater is known for its high flavonoid content.

14: What fraction of flavonoid intake in the diet is absorbed by the human body?
A: Less than 1%
B: Less than 5%
C: Less than 10%
D: Less than 20%
Correct Answer: B
Explanation: Flavonoids are poorly absorbed by the human body, with less than 5% typically absorbed.

15: Which test for detection of flavonoids involves a pink or red color change after adding magnesium filings and hydrochloric acid?
A: Sodium hydroxide test
B: DMACA test
C: Shinoda test
D: AlCl3 method
Correct Answer: C
Explanation: The Shinoda test detects flavonoids by a pink or red color change.

16: Which disease’s origin has been implicated to involve inflammation, despite no clinical evidence of dietary flavonoid effects on it?
A: Diabetes mellitus
B: Cardiovascular disease
C: Cancer
D: All of the above
Correct Answer: D
Explanation: Inflammation is connected to diseases like cancer, cardiovascular disorders, and diabetes, but there’s no clinical evidence that flavonoids affect these conditions.

17: What color light promotes flavonoid synthesis in plants?
A: Blue
B: Green
C: Red
D: Yellow
Correct Answer: C
Explanation: Red light promotes flavonoid synthesis through phytochrome-mediated pathways in plants.

18: Which microorganism has been shown to produce flavonoid molecules through genetic engineering?
A: E. coli
B: Rhizobium
C: Saccharomyces cerevisiae
D: Lactobacillus
Correct Answer: A
Explanation: Genetically engineered E. coli has been shown to produce flavonoid molecules.

19: Which specific health claim regarding cocoa flavanols was permitted by EFSA in 2013?
A: Reduces cholesterol
B: Controls blood sugar levels
C: Maintains the elasticity of blood vessels
D: Relieves joint pain
Correct Answer: C
Explanation: In 2013, EFSA allowed the claim that 200 mg/day of cocoa flavanols “help[s] maintain the elasticity of blood vessels.”

20: What is the shell of the aglycone flavonoids comprised of?
A: Two carbon rings
B: Three carbon rings
C: Four carbon rings
D: Five carbon rings
Correct Answer: B
Explanation: The aglycone form of flavonoids consists of three carbon rings connected by a three-carbon linking chain.

21: Which food source has the highest flavonol content per 100g?
A: Red onion
B: Parsley
C: Lemon
D: Thyme
Correct Answer: B
Explanation: Fresh parsley has a high flavonol content ranging from 8 to 10 mg/100 g sample.

22: Which glycoside-bound form of flavonoids is most commonly consumed in the diet?
A: Flavan-3-ols
B: Flavones
C: Flavonols
D: Isoflavones
Correct Answer: C
Explanation: Flavonols, in glycoside-bound form, are widely consumed in the human diet.

23: In the human diet, what do flavonoids contribute to aside from their low toxicity?
A: Vitamin supply
B: Antioxidant activity
C: Pigmentation
D: Protein content
Correct Answer: B
Explanation: Flavonoids, despite their low toxicity, contribute to the antioxidant activity in the diet.

24: Which molecule’s production in the body is attributed to the increase in antioxidant capacity after consuming flavonoid-rich foods?
A: Glucose
B: Uric acid
C: Ascorbic acid
D: Tannins
Correct Answer: B
Explanation: The increase in antioxidant capacity is due to uric acid production rather than directly from flavonoids.

25: What process in phytochrome-mediated flavonoid biosynthesis is accepted by high energy radiations?
A: Phytochromes
B: Carotenoids
C: Cryptochromes
D: Flavins
Correct Answer: B
Explanation: Carotenoids accept high energy radiations in the process of phytochrome-mediated flavonoid biosynthesis.

26: Flavan-3-ols are also known by what common term?
A: Flavones
B: Anthocyanidins
C: Flavonoids
D: Catechins
Correct Answer: D
Explanation: Flavan-3-ols are commonly referred to as catechins.

27: How is the total flavonoid content of a sample determined according to the AlCl3 method?
A: By measuring color change with DMACA
B: By reading absorbance at 440 nm
C: By yellow coloration with sodium hydroxide
D: By pink coloration with hydrochloric acid
Correct Answer: B
Explanation: The AlCl3 method determines total flavonoid content by reading the absorbance of the solution at 440 nm.

28: What is created by the microbial metabolism of dietary flavonoids in the human body?
A: Antioxidants
B: Smaller fragments
C: Larger polymers
D: Vitamin P
Correct Answer: B
Explanation: Flavonoids are quickly metabolized into smaller fragments by microbial metabolism in the human body.

29: Which color change in the sodium hydroxide test indicates the presence of flavonoids?
A: Blue to green
B: Yellow to colorless
C: Red to pink
D: Violet to clear
Correct Answer: B
Explanation: The presence of flavonoids is indicated by a yellow to colorless change when dilute hydrochloric acid is added.

30: What kind of pigmented role do flavonoids play in higher plants?
A: Leaf color
B: Root pigments
C: Flower coloration
D: Stem color
Correct Answer: C
Explanation: Flavonoids are the main pigments responsible for the coloration in the flowers of higher plants.

31: Which country had a mean flavonoid intake of 140 mg/d based on EFSA data?
A: USA
B: Canada
C: Japan
D: European Union
Correct Answer: D
Explanation: The European Union had a mean flavonoid intake of 140 mg/d, though it varied among countries.

32: What type of plant compound are flavonoids considered due to their wide distribution and consumption levels?
A: Alkaloids
B: Phytosterols
C: Polyphenols
D: Terpenes
Correct Answer: C
Explanation: Flavonoids are considered polyphenols due to their widespread occurrence and significant dietary consumption.

33: What must be added to the ethanolic extract during the Shinoda test to indicate the presence of flavonoids?
A: Magnesium filings and hydrochloric acid
B: Sodium hydroxide and phenolphthalein
C: Copper sulfate and ammonia
D: Potassium permanganate and sulfuric acid
Correct Answer: A
Explanation: Magnesium filings and hydrochloric acid are added in the Shinoda test for flavonoids detection.

34: What ion skeleton is used by anthocyanidins?
A: Flavylium
B: Furan
C: Chromene
D: Xanthine
Correct Answer: A
Explanation: Anthocyanidins use the flavylium (2-phenylchromenylium) ion skeleton.

35: Which dietary source is known for containing both flavonoids and significant polyphenol content?
A: Apples
B: Peanut skin
C: Potatoes
D: Carrots
Correct Answer: B
Explanation: Peanut skin is known for its significant polyphenol content, including flavonoids.

36: What is the effect of habitual flavonoid intake on the human gut microbiome?
A: Increases vitamin absorption
B: Reduces protein synthesis
C: Unknown
D: Promotes microbiome growth
Correct Answer: C
Explanation: The effect of habitual flavonoid intake on the human gut microbiome remains unknown.

37: What does red grapefruit contain high levels of?
A: Proteins
B: Flavonoids
C: Carotenoids
D: Alkaloids
Correct Answer: B
Explanation: Citrus fruits, including red grapefruit, are rich in flavonoids.

38: Which region contains the glycoside-bound flavonoids most commonly consumed in the diet?
A: Northern America
B: Europe
C: Asia
D: No specific region
Correct Answer: A
Explanation: The glycoside-bound form of flavonoids is predominantly consumed in Northern America.

39: What type of flavonoids are present in relatively greater amounts in the peels of citrus fruits compared to their pulp?
A: Flavonols
B: Flavan-3-ols
C: Flavanones
D: Isoflavones
Correct Answer: C
Explanation: Flavanones are present in higher concentrations in the peels of citrus fruits compared to their pulp.

40: What is the use of flavonoids in higher plants aside from floral pigmentation?
A: Nitrogen fixation
B: Carbon storage
C: Photosynthesis
D: Water transport
Correct Answer: A
Explanation: Flavonoids in higher plants play a role in nitrogen fixation among other functions.

41: Which class of flavonoids helps plants in UV filtration?
A: Anthocyanidins
B: Flavanones
C: Isoflavonoids
D: Chalcones
Correct Answer: C
Explanation: Isoflavonoids assist plants in UV filtration among other functions.

42: What process uses immobilized Candida antarctica lipase in regard to flavonoids?
A: Synthesis
B: Acylation
C: Detection
D: Degradation
Correct Answer: B
Explanation: Immobilized Candida antarctica lipase is used to catalyze the regioselective acylation of flavonoids.

43: Why did the FDA warn manufacturers like Unilever about their advertising claims for flavonoids?
A: Due to excessive sugar content
B: For misleading health claims
C: Because of poor packaging
D: To prevent unfair competition
Correct Answer: B
Explanation: The FDA warned against misleading health claims regarding flavonoids, such as lowering cholesterol or relieving pain.

44: Which test for flavonoid detection uses the chromogen p-dimethylaminocinnamaldehyde (DMACA)?
A: Shinoda test
B: Sodium hydroxide test
C: DMACA test
D: AlCl3 method
Correct Answer: C
Explanation: The DMACA test is a colorimetric assay based on reactions with p-dimethylaminocinnamaldehyde.

45: Which subgroups include Proanthocyanidins formed from flavanols?
A: Dimers, trimers, oligomers, or polymers
B: Monomers, dimers, tetramers
C: Polymers only
D: Monomers only
Correct Answer: A
Explanation: Proanthocyanidins are dimers, trimers, oligomers, or polymers formed from flavanols.

46: According to IUPAC, which structure does not have hydroxyl group substitution on carbon at position 2?
A: Flavanone
B: Isoflavones
C: Flavonol
D: Chalcones
Correct Answer: B
Explanation: Isoflavones do not have a hydroxyl group substitution on the carbon at position 2.

47: What is the primary chemical structure of neoflavonoids derived from?
A: 2-Phenylchromen-4-one
B: 3-Phenyl-1,4-benzopyrone
C: 4-Phenylcoumarin
D: 4-Phenylchromen-2-one
Correct Answer: C
Explanation: Neoflavonoids are derived from the 4-phenylcoumarin (4-phenyl-1,2-benzopyrone) structure.

48: Which specific flavonoid was permitted by both EFSA and the FDA for health claims related to cardiovascular benefits?
A: Quercetin
B: Cocoa flavanols
C: Hesperidin
D: Catechins
Correct Answer: B
Explanation: Cocoa flavanols were allowed by EFSA and FDA for claims regarding cardiovascular health benefits.

49: What type of flavonoids are primarily involved in flower color in higher plants?
A: Flavones
B: Anthocyanins
C: Chalcones
D: Isoflavones
Correct Answer: B
Explanation: Anthocyanins are the primary pigments for flower coloration in higher plants.

50: What did studies find in terms of the relationship between flavan-3-ol intake and cardiovascular disease mortality?
A: Strong positive association
B: Strong inverse association
C: No significant association
D: Mixed results
Correct Answer: C
Explanation: No significant association has been found between flavan-3-ol intake and cardiovascular disease mortality.

51: Which method uses absorbance at 440 nm for quantifying flavonoid content?
A: DMACA test
B: Sodium hydroxide test
C: AlCl3 method
D: Shinoda test
Correct Answer: C
Explanation: The AlCl3 method quantifies flavonoid content by measuring absorbance at 440 nm.

52: Which antioxidant activity in flavonoid-rich foods is attributed to uric acid production?
A: Direct impact of flavonoids
B: Result of microbial metabolism
C: Consumption and excretion
D: Flavonoid polymerization
Correct Answer: C
Explanation: The body’s increased antioxidant capacity after consuming flavonoid-rich foods is due to uric acid production resulting from flavonoid consumption and excretion.

53: How are flavonoids classified for dietary purposes?
A: Based on their color
B: By their bioavailability
C: According to their chemical structure
D: By their source plants
Correct Answer: C
Explanation: Flavonoids are classified according to their chemical structure for dietary purposes.

54: Which beverage was included in the FDA’s warning for making misleading health claims about flavonoids?
A: Lipton tea
B: Starbucks coffee
C: Tropicana juice
D: Coca-Cola
Correct Answer: A
Explanation: The FDA warned Lipton tea’s manufacturer, Unilever, for making misleading health claims about flavonoids.

55: What is the primary phenolic compound in human diets discussed in the text?
A: Flavonoids
B: Alkaloids
C: Tannins
D: Pterocarpans
Correct Answer: A
Explanation: Flavonoids are the most common group of polyphenolic compounds in human diets.

56: What triggers the secretion of Nod factors in Rhizobia, leading to root nodule formation in legumes?
A: Carbs
B: Proteins
C: Flavonoids
D: Minerals
Correct Answer: C
Explanation: Flavonoids trigger the secretion of Nod factors by Rhizobia in the soil, which facilitates the formation of root nodules in legumes.

57: What skeleton is used for synthesizing isoflavones?
A: 4-Phenylcoumarin
B: 2-Phenylchromen-4-one
C: 3-Phenylchromen-4-one
D: 4-Phenylchromen-2-one
Correct Answer: C
Explanation: Isoflavones use the 3-phenylchromen-4-one skeleton for their synthesis.

58: What is the main health claim approved by the FDA in 2023 regarding cocoa flavanols?
A: They can reduce cholesterol
B: They can relieve pain
C: They can maintain blood vessel elasticity
D: They can aid weight loss
Correct Answer: C
Explanation: The FDA acknowledged that 200 mg per day of cocoa flavanols might support cardiovascular health by maintaining the elasticity of blood vessels.

59: How do plants initiate flavonoid biosynthesis through light exposure?
A: By absorbing low energy radiations
B: By converting UV rays
C: Through red light exposure
D: Through green light exposure
Correct Answer: C
Explanation: Red light exposure promotes phytochrome-mediated flavonoid biosynthesis in plants.

60: Which test differentiates flavonoids by changing color from yellow to colorless upon the addition of dilute hydrochloric acid?
A: Shinoda test
B: Dimethylaminocinnamaldehyde (DMACA) test
C: Sodium hydroxide test
D: AlCl3 method
Correct Answer: C
Explanation: The sodium hydroxide test indicates the presence of flavonoids through a color change from yellow to colorless upon the addition of dilute hydrochloric acid.

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