A Few Chemical Groups Are Key to Molecular Function ✏ Practice Questions

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Rucete ✏ Campbell Biology In a Nutshell

Unit 1 THE CHEMISTRY OF LIFE — Concept 4.3 A Few Chemical Groups Are Key to Molecular Function — Practice Questions


(Multiple Choice — Click to Reveal Answer)

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1. What determines many of the unique properties of organic molecules?

  1. Mass of the atoms
  2. The type of isomers
  3. The functional groups attached
  4. The number of protons
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3. The functional groups attached

2. What is the function of the carboxyl group?

  1. Acts as a base
  2. Acts as an acid
  3. Forms double bonds
  4. Stores energy
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2. Acts as an acid

3. What does the amino group do in biological systems?

  1. Donate a phosphate
  2. Act as an acid
  3. Act as a base
  4. Break down water
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3. Act as a base

4. Which group is nonreactive but affects gene expression?

  1. Phosphate
  2. Methyl
  3. Carboxyl
  4. Hydroxyl
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2. Methyl

5. What group forms alcohols?

  1. Hydroxyl
  2. Sulfhydryl
  3. Carbonyl
  4. Amine
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1. Hydroxyl

6. Which group contains a carbon double bonded to oxygen?

  1. Carboxyl
  2. Methyl
  3. Carbonyl
  4. Hydroxyl
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3. Carbonyl

7. What group forms ketones or aldehydes?

  1. Amino
  2. Carbonyl
  3. Sulfhydryl
  4. Phosphate
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2. Carbonyl

8. Which group helps stabilize protein structures via cross-links?

  1. Phosphate
  2. Sulfhydryl
  3. Hydroxyl
  4. Methyl
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2. Sulfhydryl

9. What functional group gives vinegar its sour taste?

  1. Amino
  2. Carbonyl
  3. Carboxyl
  4. Methyl
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3. Carboxyl

10. What happens to ATP when it releases energy?

  1. It becomes AMP
  2. It forms a peptide bond
  3. It loses a phosphate group
  4. It gains oxygen
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3. It loses a phosphate group

11. What chemical group is responsible for the negative charge on ATP?

  1. Amino
  2. Methyl
  3. Hydroxyl
  4. Phosphate
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4. Phosphate

12. Which group is involved in energy transfer?

  1. Sulfhydryl
  2. Phosphate
  3. Carbonyl
  4. Methyl
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2. Phosphate

13. Which functional group is a base and can accept a hydrogen ion?

  1. Amino
  2. Carboxyl
  3. Phosphate
  4. Hydroxyl
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1. Amino

14. What is the compound name for the hydroxyl group?

  1. Thiol
  2. Amine
  3. Alcohol
  4. Ketone
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3. Alcohol

15. Which group is typically written as –SH?

  1. Sulfhydryl
  2. Hydroxyl
  3. Carboxyl
  4. Methyl
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1. Sulfhydryl

16. Which group forms the base structure of amino acids?

  1. Methyl and Carbonyl
  2. Hydroxyl and Carbonyl
  3. Carboxyl and Amino
  4. Phosphate and Methyl
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3. Carboxyl and Amino

17. What is the biological function of a methyl group?

  1. Energy production
  2. Acid donation
  3. Gene expression regulation
  4. Electron transport
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3. Gene expression regulation

18. Which group makes compounds more hydrophilic?

  1. Methyl
  2. Phosphate
  3. Hydroxyl
  4. Both 2 and 3
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4. Both 2 and 3

19. In water, which group ionizes and contributes a negative charge?

  1. Carboxyl
  2. Carbonyl
  3. Phosphate
  4. Methyl
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3. Phosphate

20. What type of reaction occurs when ATP reacts with water?

  1. Condensation
  2. Hydrolysis
  3. Dehydration
  4. Oxidation
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2. Hydrolysis

21. Which group is NOT considered chemically reactive?

  1. Hydroxyl
  2. Phosphate
  3. Methyl
  4. Carboxyl
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3. Methyl

22. What group is found in ketones and aldehydes?

  1. Carbonyl
  2. Hydroxyl
  3. Methyl
  4. Phosphate
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1. Carbonyl

23. What property makes the hydroxyl group polar?

  1. Hydrogen bonding
  2. Oxygen’s electronegativity
  3. Covalent bonding
  4. Ionization
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2. Oxygen’s electronegativity

24. Which of the following is a thiol compound?

  1. Glycine
  2. Propanal
  3. Cysteine
  4. Acetone
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3. Cysteine

25. What does ATP become after releasing one phosphate group?

  1. AMP
  2. ADP
  3. Pi
  4. RNA
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2. ADP


26. Why is the methyl group not considered a functional group in the strict chemical sense?

  1. It is too reactive
  2. It is a charged group
  3. It does not participate in chemical reactions directly
  4. It forms ionic bonds
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3. It does not participate in chemical reactions directly

27. Which chemical group is often added to DNA to regulate gene expression?

  1. Carboxyl
  2. Phosphate
  3. Methyl
  4. Sulfhydryl
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3. Methyl

28. What allows the phosphate group to release energy when transferred?

  1. Its ability to form a hydrophobic tail
  2. Its ionic character
  3. Its polarity and negative charge
  4. The breaking of strong hydrogen bonds
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3. Its polarity and negative charge

29. What type of reaction transforms ATP into ADP and inorganic phosphate?

  1. Isomerization
  2. Hydrolysis
  3. Oxidation
  4. Condensation
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2. Hydrolysis

30. In cysteine, which group is responsible for forming disulfide bridges?

  1. Carboxyl
  2. Sulfhydryl
  3. Hydroxyl
  4. Phosphate
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2. Sulfhydryl

31. What property allows phosphate groups to contribute to the solubility of organic molecules?

  1. Hydrophobicity
  2. Presence of methyl groups
  3. Negative charges
  4. Covalent carbon bonds
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3. Negative charges

32. How does the functional group of testosterone differ from estradiol?

  1. Testosterone has a hydroxyl group; estradiol has a carboxyl
  2. Estradiol contains a carbonyl group not present in testosterone
  3. Each contains slightly different groups that alter molecular shape
  4. They are identical in structure and function
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3. Each contains slightly different groups that alter molecular shape

33. What functional group is found in both amino acids and ATP?

  1. Sulfhydryl
  2. Phosphate
  3. Carboxyl
  4. Carbonyl
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2. Phosphate

34. Which group is involved in forming esters in biological molecules like phospholipids?

  1. Methyl
  2. Phosphate
  3. Carbonyl
  4. Sulfhydryl
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2. Phosphate

35. How does the carbonyl group differ when part of a ketone versus an aldehyde?

  1. Ketones have the carbonyl at the end of a chain; aldehydes in the middle
  2. Aldehydes are hydrophobic; ketones are not
  3. Ketones have internal carbonyl; aldehydes have terminal carbonyl
  4. There is no difference
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3. Ketones have internal carbonyl; aldehydes have terminal carbonyl

36. What distinguishes a functional group from other chemical groups in organic molecules?

Show Answer

Functional groups participate directly in chemical reactions and have consistent properties like shape and charge that influence molecular behavior.

37. Why is the methyl group not considered chemically reactive?

Show Answer

Because it does not typically participate in chemical reactions; it mainly serves as a recognizable tag on biological molecules.

38. How does the structure of testosterone differ from estradiol, and how does this affect function?

Show Answer

They differ only in a few chemical groups attached to the same carbon skeleton; these groups affect molecular shape, leading to different effects on target tissues.

39. What happens to ATP when it reacts with water?

Show Answer

It undergoes hydrolysis, releasing one phosphate group and energy, and becomes ADP (adenosine diphosphate).

40. How do phosphate groups contribute to the energy-releasing capability of ATP?

Show Answer

The negative charges on phosphate groups create repulsion; breaking the bonds releases energy that can be used by cells.

41. Why are functional groups like hydroxyl and phosphate typically hydrophilic?

Show Answer

Because they contain polar bonds or charges that form hydrogen bonds with water, increasing solubility.

42. What is the role of the sulfhydryl group in protein structure?

Show Answer

It forms disulfide bridges (covalent bonds) between cysteine residues, helping to stabilize protein structure.

43. What distinguishes a ketone from an aldehyde in terms of carbonyl group placement?

Show Answer

In a ketone, the carbonyl group is located within the carbon skeleton; in an aldehyde, it's at the end of the chain.

44. How can a small chemical change in a functional group alter a molecule's biological activity?

Show Answer

It can change the molecule’s shape or polarity, affecting how it interacts with receptors or enzymes in biological systems.

45. What happens to the carboxyl and amino groups at normal cellular pH?

Show Answer

They ionize: the carboxyl group loses a proton (becomes COO⁻), and the amino group gains a proton (becomes NH₃⁺).

46. Describe how the methylation of DNA affects gene expression.

Show Answer

Methylation can silence genes by preventing transcription factors from binding or altering chromatin structure.

47. Which functional group is commonly involved in energy transfer reactions?

Show Answer

The phosphate group, especially in molecules like ATP.

48. Why is ATP considered to have "potential" rather than "stored" energy?

Show Answer

Because it releases energy only when it reacts with water (hydrolysis); the potential lies in its ability to react.

49. What is the compound name for a molecule with a hydroxyl group?

Show Answer

Alcohol (usually ends in –ol, e.g., ethanol).

50. How does the addition of a functional group change the behavior of a hydrocarbon?

Show Answer

It alters the molecule’s reactivity, solubility, and ability to interact with biological molecules by introducing polarity or charge.

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