Test your basic knowledge |

Food Chemistry

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. Q What reaction does the enzyme 'reverse transcriptase' catalyze?
Anomeric
Water
RNA transcribed to DNA
They are natural - nontoxic substances - generally catalyze without unwanted side-effects - active under very mild conditions of temperature and pH - active at low concentrations - rate of reaction can be controlled - can be inactivated after reactio

2. What is the structural difference between chlorophyll and pheophytia?
2-mercaptoethanol (2-ME) - dithiothreitol (DDT)
Pheophytin forms
Pheophytia does not have magnesium in porphyrin ring.
Emulsification

3. How many polypeptide chains make up an antibody?
Four
HLB (hydrophilic-lipophilic balance); a low value (3-6) promotes water in oil emulsions and a high value (8-18) promotes oil in water emulsions.
Fatty Acid (Ester linked) to Fatty Alcohol
V=IR and P=VI or I x I x are

4. Name two reasons why fats are hydrogenated.
Initiation - Propagation - Termination
It allows the conversion of liquid oils into semisolid or plastic fats and it improves the oxidative stability of the fat.
They are natural - nontoxic substances - generally catalyze without unwanted side-effects - active under very mild conditions of temperature and pH - active at low concentrations - rate of reaction can be controlled - can be inactivated after reactio
Speed of Light

5. What is the major color compound in tomatoes?
Sucrose
Four
Lycopenes
Emulsification

6. What is the enzyme responsible for browning in apples and lettuce?
Polyphenol Oxidase
Aspartic Acid and Phenylalanine
Pectin methylesterase & polygalacturonase
Corn- Lysine - Potato-Methionine - Green Peas-Methionine

7. What are the fructose contents in commercial HFCS products.
Primary-amino acid sequence. Secondary-alpha-helix - beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.
Pheophytia does not have magnesium in porphyrin ring.
45% - 52% - 90%
Proportion of solids in the fat - number - size - and kinds of crystals - viscosity of the liquid - temperature treatment - and mechanical working.

8. A) Is the major component of most foods.B) Controls shelf-life or storage capabilityC) Regulates chemical and microbiological reactionsD) All of the above
Pectin methylesterase & polygalacturonase
Water
Oil in Water
Emulsoids

9. What is the chemical nature of anthocyanins?
Pectins
Four
Glycosides of anthocyanidins
Blue pigment in flowers

10. Does kosmotrophil ion discourage water structure?
No
Osmosis
NaCl (it dissociated to a 2M solution)
Plasmids

11. What does the saponification value measure and how is it measured?
Chlocophyllide does not have a phytoltail
Number of fatty acids present; mg KOH needed to saponify 1 g fat.
Initiation - Propagation - and Termination
Anthocyanins

12. Name three effects of protein denaturation.
Decreased solubility - altered water-binding capacity - loss of biological activity - increased susceptibility to attack by proteases - increased intrinsic viscosity - inability to crystallize.
Sodium chloride reduces foam stability and sucrose improves foam stability.
Egg white proteins - the globin part of hemoglobin - bovine serum albumin - gelatin - whey proteins - casein micelles - B-casein - wheat proteins - soy proteins - and some protein hydrolyzates.
For proteins: SDA-PAGE. For DNA & RNA: Agarose gel.

13. What are proteins which are soluble in 50-80% ethanol known as?
Onions ( or leeks)
Capsaicin
Primary butyric acid also caproic acid.
Prolamines

14. What is the structural difference between chlorophyll and pheophytia?
Pheophytia does not have magnesium in porphyrin ring.
Cis
It allows the conversion of liquid oils into semisolid or plastic fats and it improves the oxidative stability of the fat.
pH 3-5

15. What does Reichert-Meissert Number measure?
Chitin
Acids - Alkalis - Metals - Organic Solvents - and Aqueous Solutions of Organic Solvents
Covalent (strongest) and Hydrophobic (Weakest)
Primary butyric acid also caproic acid.

16. What are the primary secondary - tertiary - and quaternary structures?
Acids - Alkalis - Metals - Organic Solvents - and Aqueous Solutions of Organic Solvents
Primary-amino acid sequence. Secondary-alpha-helix - beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.
Lipase
Parabens

17. During freezing What are the two stages in the crystallization process?
Nucleation or crystal formation and crystal growth.
Polyphenols
Troponins and Tropomyosin
Butter= water in oil Mayonnaise= oil in water Milk= oil in water

18. What charge will a protein have when the pH of its solution is below at - and above its pKa?
Non-protein nitrogen
pH below positive charge; pH at no charge; pH above negative charge
Number of fatty acids present; mg KOH needed to saponify 1 g fat.
Fatty acid composition - free fatty acids versus the corresponding glycerols - oxygen concentration - temperature - surface area - moisture - pro-oxidants - antioxidants

19. What is an isomer that is cheaper than Vitamin C?
Tryptophan
Proportion of solids in the fat - number - size - and kinds of crystals - viscosity of the liquid - temperature treatment - and mechanical working.
Erythorbic Acid
Thamautin

20. What is the enzyme responsible for browning in apples and lettuce?
Troponins and Tropomyosin
Polyphenol Oxidase
Pectin Esterase - Polygalacturonase - Pectin Layase
Browning of freshly cut surfaces of fruits and vegetables.

21. What name is given to the small circular DNA molecules that carry genetic information independently of the main bacterial chromosome?
Plasmids
Four
Proportion of solids in the fat - number - size - and kinds of crystals - viscosity of the liquid - temperature treatment - and mechanical working.
Pheophytin forms

22. If the absorption of a sample is being determined spectrophotometrically at 420 nm what color is the sample?
Yellow
Egg white proteins - the globin part of hemoglobin - bovine serum albumin - gelatin - whey proteins - casein micelles - B-casein - wheat proteins - soy proteins - and some protein hydrolyzates.
Chlocophyllide does not have a phytoltail
Amount of free fatty acids present; mg KOH needed to neutralize the free fatty acids in 1 g of fat.

23. Name two enzymes that are involved in softening fruits.
Phenophylin
Pectin Esterase - Polygalacturonase - Pectin Layase
HPLC has higher pressure than FPLC
Lipase - lipoxygenase - catalase - chlorophylase - peroxidase - pectinase - protease - ascorbic acid oxidase - alkaline phosphotase.

24. Is a disaccharide
DNA transferred by cell to cell contact (bacterial sex).
pH 3-5
Sucrose
Lipase

25. What is the name of the structural carbohydrate found in lobsters crab - shellfish - and insects?
Milk
20 carbons and 4 double bonds
Chitin
Lamellar; Hexagonal I - II; Cubic

26. A chlorophyll molecule reacting with hydrogen exhibits what shade of green?
Lycopenes
Pectin Esterase
Olive Green
Sodium bicarbonate generates CO2

27. Peptide bond formation results in the formation of what secondary compound?
Water
Ascorbic Acid and Citric Acid
No
Arachidonic Acid

28. During freezing What are the two stages in the crystallization process?
pH 3-5
Nucleation or crystal formation and crystal growth.
Egg white proteins - the globin part of hemoglobin - bovine serum albumin - gelatin - whey proteins - casein micelles - B-casein - wheat proteins - soy proteins - and some protein hydrolyzates.
Glycosides of anthocyanidins

29. What are soluble polymers of anhydro-galacturonic acid and its esters called?
For proteins: SDA-PAGE. For DNA & RNA: Agarose gel.
Pectins
It allows the conversion of liquid oils into semisolid or plastic fats and it improves the oxidative stability of the fat.
Corn- Lysine - Potato-Methionine - Green Peas-Methionine

30. What happens to chlorophyll on heating?
Primary-amino acid sequence. Secondary-alpha-helix - beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.
Pheophytin forms
Acetoin
Sucrose

31. What is the fundamental driving of electrophoresis?
It explodes
The speed of a molecule is proportional to the surrounding voltage gradient.
Gossypol (it is removed during the oil refining process)
Chlocophyllide does not have a phytoltail

32. What is the name of the degradation compound of chlorophyll?
2-mercaptoethanol (2-ME) - dithiothreitol (DDT)
Cis
Amount of free fatty acids present; mg KOH needed to neutralize the free fatty acids in 1 g of fat.
Phenophylin

33. Name two main gluten proteins.
EDTA - citric acid - malic acid - tartaric acid - oxalic acid - succinic acid - adenosine triphosphate - pyrophosphate - porphyrins - and proteins.
Decreased solubility - altered water-binding capacity - loss of biological activity - increased susceptibility to attack by proteases - increased intrinsic viscosity - inability to crystallize.
Yellow
Gliadins and Glutenins

34. What is Carboxy-methyl cellulose often used for?
Carrageenan
Chlocophyllide does not have a phytoltail
Thickener in foods
HPLC has higher pressure than FPLC

35. What degradative enzyme causes browning in apples - pears - bananas - and peaches?
Thamautin
Thickener in foods
Polyphenoloxidase
Microorganisms are very versatile - MO's can be altered by mutations or genetic engineering to produce a greater quantity of enzyme or different enzymes - recovery of enzymes is often easy - readily available - high rate of growth and enzyme producti

36. What happens to a bottle of wine if before you bottle it you forget to put the stuff in it that prevents it from fermenting?
Plasmids
Anthocyanins
It explodes
Orange Juice

37. Which two amino acids is the aspartame derived from?
Cooling the oil and filtering of the solids formed so that long chained saturated fats do not crystallize at low temperatures.
1 - 3 - 7-trimethylxanthine
Aspartic Acid and Phenylalanine
Thickener in foods

38. Name 3 factors influencing the rate of lipid oxidation in foods.
Fat Oxidation
Amount of free fatty acids present; mg KOH needed to neutralize the free fatty acids in 1 g of fat.
Pectin methylesterase & polygalacturonase
Fatty acid composition - free fatty acids versus the corresponding glycerols - oxygen concentration - temperature - surface area - moisture - pro-oxidants - antioxidants

39. Name 3 chemical agents capable of denaturing proteins.
Fatty acid composition - free fatty acids versus the corresponding glycerols - oxygen concentration - temperature - surface area - moisture - pro-oxidants - antioxidants
The amount of unsaturated bonds in fat; grams Iodine reacting with 100 grams fat.
Acids - Alkalis - Metals - Organic Solvents - and Aqueous Solutions of Organic Solvents
Gliadins and Glutenins

40. Which amino acid has the greatest molecular weight: tryptophan or tyrosine?
Linoleic Acid
Polyphenoloxidase
Tryptophan
Aspartic Acid and Phenylalanine

41. What chemical compound is responsible for the 'hot' principle of jalepeno peppers?
Capsaicin
Pectins
The degree of liquid drainage or foam collapse (foam reduction) after a given time - the time for total or half-drainage (or half-reduction in volume) - or the time before drainage starts.
Smoother - less acid and less bitter chocolate flavor - darker color - and improved solubility (elevated pH enhances sugar-amino browning reactions and polymerization of flavonoids).

42. What is the structural difference between chlorophyll and chlocophyllide?
Chlocophyllide does not have a phytoltail
Bright green
Lycopenes
Aspartic Acid and Phenylalanine

43. What is Carboxy-methyl cellulose often used for?
HLB (hydrophilic-lipophilic balance); a low value (3-6) promotes water in oil emulsions and a high value (8-18) promotes oil in water emulsions.
Thickener in foods
Cooling the oil and filtering of the solids formed so that long chained saturated fats do not crystallize at low temperatures.
.05

44. What happens to chlorophyll on heating?
Pheophytin forms
Polyphenol Oxidase
Fatty acid composition - free fatty acids versus the corresponding glycerols - oxygen concentration - temperature - surface area - moisture - pro-oxidants - antioxidants
HPLC has higher pressure than FPLC

45. Are sorbitol and mannitol sweet?
Ammonia - Water - Carbon Dioxide
Fatty Acid and Alcohol
Thickener in foods
Yes

46. In polyacrylamide gel electrophoresis (PAGE) what purpose do ammonium persulfates (APS) and TEMED serve?
Fructose
Cooling the oil and filtering of the solids formed so that long chained saturated fats do not crystallize at low temperatures.
They act as catalysts - speeding the polymerization of acrylamide.
Milk

47. Which two amino acids is the aspartame derived from?
Anomeric
It explodes
14
Aspartic Acid and Phenylalanine

48. What does the acronym NPN stand for?
Monosodium Glutamate
Erythorbic Acid
Non-protein nitrogen
Cis

49. What are proteins which are soluble in 50-80% ethanol known as?
Prolamines
Sodium bicarbonate generates CO2
Non-protein nitrogen
The amount of unsaturated bonds in fat; grams Iodine reacting with 100 grams fat.

50. What is the acid present in fish oil?
Ammonia - Water - Carbon Dioxide
Negative log of the hydrogen concentration (mol/l).
Amount of free fatty acids present; mg KOH needed to neutralize the free fatty acids in 1 g of fat.
Arachidonic Acid