Biology Exam 2 Review: Macromolecules, Membranes, Enzymes, and Cellular Processes

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Q1. What is a polymer? Give examples of the four major biological polymers.

Background

Topic: Biological Macromolecules

This question tests your understanding of the definition of polymers and your ability to identify the four main types of biological polymers found in living organisms.

Key Terms

Polymer: A large molecule made up of repeating subunits (monomers) joined together by covalent bonds.
Monomer: The small, basic building block that joins with others to form a polymer.
Examples: Carbohydrates, proteins, nucleic acids, and (with caveats) lipids.

Step-by-Step Guidance

Start by defining what a polymer is in your own words, focusing on the concept of repeating monomer units.
List the four major classes of biological polymers. For each, think about what their monomers are.
Give a specific example for each class (e.g., starch for carbohydrates, DNA for nucleic acids, etc.).
Remember that lipids are sometimes considered separately because they do not always fit the strict definition of a polymer.

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Q2. What is the difference between a monomer and a polymer?

Background

Topic: Macromolecule Structure

This question checks your understanding of the relationship between monomers and polymers in biological molecules.

Key Terms

Monomer: Single, small molecule that can join with others to form a polymer.
Polymer: Large molecule made of many monomers linked together.

Step-by-Step Guidance

Define 'monomer' and 'polymer' clearly, emphasizing the size and complexity difference.
Explain how monomers are joined to form polymers (mention covalent bonds).
Provide an example (e.g., amino acids are monomers that form protein polymers).

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Q3. Describe dehydration synthesis (condensation) and hydrolysis reactions. What is removed or added, and which reaction builds vs. breaks polymers?

Background

Topic: Chemical Reactions in Biology

This question tests your understanding of how biological macromolecules are built and broken down.

Key Terms and Concepts

Dehydration synthesis (condensation): Reaction that joins two monomers by removing a water molecule.
Hydrolysis: Reaction that breaks a polymer into monomers by adding a water molecule.

Step-by-Step Guidance

Define dehydration synthesis and hydrolysis, focusing on the role of water in each.
State which process builds polymers and which breaks them down.
Describe what is removed or added during each reaction (water).
Give an example of each reaction (e.g., forming a peptide bond vs. breaking one).

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Q4. List the four major classes of macromolecules and state at least one major function for each.

Background

Topic: Biological Macromolecules and Their Functions

This question tests your ability to identify the main types of macromolecules and their biological roles.

Key Terms

Carbohydrates
Proteins
Nucleic acids
Lipids

Step-by-Step Guidance

List each class of macromolecule.
For each, state one major function (e.g., energy storage, genetic information, etc.).
Think of examples that illustrate each function.

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Q5. Why are lipids not considered true polymers/macromolecules in the same way as the others?

Background

Topic: Structure of Biological Molecules

This question tests your understanding of what defines a polymer and why lipids are an exception.

Key Terms

Polymer: Made of repeating monomer units.
Lipids: Often made from smaller molecules (glycerol + fatty acids) but not repeating monomers in a chain.

Step-by-Step Guidance

Recall the definition of a polymer and how most macromolecules fit this definition.
Explain how lipids are assembled (e.g., triglycerides from glycerol and fatty acids).
Discuss why this structure does not fit the strict definition of a polymer.

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Q6. Identify the building blocks (monomers) of each major macromolecule.

Background

Topic: Macromolecule Structure

This question tests your knowledge of the monomers that make up each class of biological macromolecule.

Key Terms

Carbohydrates → Monosaccharides
Proteins → Amino acids
Nucleic acids → Nucleotides
Lipids → Glycerol + fatty acids (not true polymers)

Step-by-Step Guidance

List each macromolecule class.
Identify the monomer or basic building block for each.
Note the exception for lipids.

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Q7. What types of bonds are formed when monomers join to make polymers?

Background

Topic: Chemical Bonds in Macromolecules

This question tests your knowledge of the specific covalent bonds that link monomers in different macromolecules.

Key Terms

Glycosidic bonds (carbohydrates)
Peptide bonds (proteins)
Phosphodiester bonds (nucleic acids)
Ester bonds (triglycerides/lipids)

Step-by-Step Guidance

For each macromolecule, recall the type of bond that links its monomers.
Describe briefly how each bond is formed (e.g., dehydration synthesis).
Give an example for at least one bond type.

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Q8. Distinguish between saturated and unsaturated fatty acids (structure and properties).

Background

Topic: Lipid Structure

This question tests your understanding of the differences in structure and properties between saturated and unsaturated fatty acids.

Key Terms

Saturated fatty acid: No double bonds, straight chains, solid at room temperature.
Unsaturated fatty acid: One or more double bonds, bent chains, liquid at room temperature.

Step-by-Step Guidance

Define saturated and unsaturated fatty acids.
Describe the structural difference (presence or absence of double bonds).
Explain how this affects their physical properties (solid vs. liquid).

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Q9. Describe the structure and function of phospholipids in cell membranes.

Background

Topic: Cell Membrane Structure

This question tests your understanding of how phospholipids are structured and how this structure enables them to form biological membranes.

Key Terms

Phospholipid: Molecule with a hydrophilic (polar) head and two hydrophobic (nonpolar) fatty acid tails.
Bilayer: Arrangement of phospholipids in cell membranes.

Step-by-Step Guidance

Describe the basic structure of a phospholipid (head and tails).
Explain how the amphipathic nature (both hydrophilic and hydrophobic parts) leads to bilayer formation.
Discuss the function of the phospholipid bilayer in cells (selective permeability, barrier, etc.).

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Q10. How many different amino acids are used to build proteins in living organisms?

Background

Topic: Protein Structure

This question tests your knowledge of the diversity of amino acids in proteins.

Key Terms

Amino acid: Building block of proteins.
Standard amino acids: The set used by all living organisms.

Step-by-Step Guidance

Recall the number of standard amino acids encoded by the genetic code.
Think about why this diversity is important for protein function.

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Q11. Why is carbon so important for life?

Background

Topic: Organic Chemistry in Biology

This question tests your understanding of the unique properties of carbon that make it the backbone of biological molecules.

Key Terms

Valence electrons
Covalent bonds
Catenation (ability to form chains)
Isomer formation

Step-by-Step Guidance

List the properties of carbon that make it versatile (number of bonds, ability to form chains/rings, etc.).
Explain how these properties contribute to the diversity of organic molecules.
Give examples of different structures carbon can form (chains, rings, isomers).

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Q12. Define diffusion, facilitated diffusion, osmosis, active transport, and secondary active transport.

Background

Topic: Membrane Transport

This question tests your understanding of the different ways substances move across cell membranes.

Key Terms

Diffusion: Movement of molecules from high to low concentration.
Facilitated diffusion: Diffusion with the help of membrane proteins.
Osmosis: Diffusion of water across a selectively permeable membrane.
Active transport: Movement against the concentration gradient, requires energy.
Secondary active transport: Uses energy from an electrochemical gradient.

Step-by-Step Guidance

Define each term clearly, focusing on energy requirements and direction of movement.
Compare and contrast passive (diffusion, facilitated diffusion, osmosis) and active transport.
Give an example of each process.

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Q13. Compare and contrast passive transport vs. active transport (energy requirement, direction relative to concentration gradient).

Background

Topic: Cell Membrane Transport

This question tests your ability to distinguish between passive and active transport mechanisms.

Key Terms

Passive transport: No energy required, moves down concentration gradient.
Active transport: Requires energy, moves against concentration gradient.

Step-by-Step Guidance

Define passive and active transport.
State the energy requirements for each.
Describe the direction of movement relative to the concentration gradient.
Provide examples of each type.

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Q14. What happens to a cell in hypotonic, isotonic, and hypertonic solutions? (Include terms: turgid, plasmolysis, crenation.)

Background

Topic: Osmosis and Cell Volume

This question tests your understanding of how cells respond to different external solute concentrations.

Key Terms

Hypotonic: Solution has lower solute concentration than cell.
Isotonic: Equal solute concentration inside and outside cell.
Hypertonic: Solution has higher solute concentration than cell.
Turgid: Plant cell swollen with water.
Plasmolysis: Plant cell membrane pulls away from wall.
Crenation: Animal cell shrinks in hypertonic solution.

Step-by-Step Guidance

Define each type of solution (hypotonic, isotonic, hypertonic).
Describe the direction of water movement in each case.
Explain the effect on animal and plant cells, using the terms provided.

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Q15. How is dialysis tubing used in lab experiments to model selectively permeable membranes?

Background

Topic: Experimental Models of Membrane Transport

This question tests your understanding of how dialysis tubing can simulate cell membranes in experiments.

Key Terms

Dialysis tubing: Semi-permeable membrane used in labs.
Selectively permeable: Allows some molecules to pass, not others.

Step-by-Step Guidance

Describe what dialysis tubing is made of and its properties.
Explain how it mimics the selective permeability of cell membranes.
Give an example of a lab experiment using dialysis tubing.

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Q16. Which types of molecules can cross a phospholipid bilayer by simple diffusion, and which cannot?

Background

Topic: Membrane Permeability

This question tests your understanding of the properties that allow or prevent molecules from crossing cell membranes unaided.

Key Terms

Simple diffusion: Movement without assistance.
Small, nonpolar, lipid-soluble molecules: Can cross easily.
Ions, large polar molecules, glucose: Cannot cross unaided.

Step-by-Step Guidance

List the properties of molecules that can cross by simple diffusion.
Give examples of molecules that can and cannot cross.
Explain why certain molecules are excluded (size, charge, polarity).

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Q17. What is the source of energy for secondary active transport?

Background

Topic: Membrane Transport Mechanisms

This question tests your understanding of how secondary active transport is powered in cells.

Key Terms

Electrochemical gradient
Primary active transport (e.g., Na+/K+-ATPase pump)

Step-by-Step Guidance

Define secondary active transport.
Explain how the energy for this process is derived from gradients established by primary active transport.
Give an example (e.g., glucose transport in the intestine).

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Q18. What is the primary function of enzymes and how do they speed up reactions?

Background

Topic: Enzyme Function

This question tests your understanding of the role of enzymes in biological reactions.

Key Terms

Enzyme: Biological catalyst
Activation energy

Step-by-Step Guidance

State the primary function of enzymes in cells.
Explain how enzymes lower activation energy to speed up reactions.
Describe the concept of specificity (active site, substrate).

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Q19. Define substrate, active site, and enzyme-substrate complex.

Background

Topic: Enzyme Mechanism

This question tests your understanding of how enzymes interact with their substrates.

Key Terms

Substrate: The reactant an enzyme acts on.
Active site: The region of the enzyme where the substrate binds.
Enzyme-substrate complex: Temporary association during catalysis.

Step-by-Step Guidance

Define each term clearly.
Explain how these components interact during an enzymatic reaction.
Give an example of a specific enzyme and substrate.

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Q20. Why are enzymes described as biological catalysts?

Background

Topic: Enzyme Function

This question tests your understanding of what makes enzymes unique compared to non-biological catalysts.

Key Terms

Catalyst: Substance that speeds up a reaction without being consumed.
Biological: Occurs in living organisms.

Step-by-Step Guidance

Define what a catalyst is.
Explain why enzymes fit this definition and how they are specific to biological systems.
Discuss how enzymes are not used up in reactions.

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Q21. What is denaturation and what factors cause it?

Background

Topic: Protein Structure and Function

This question tests your understanding of how protein structure can be disrupted and the consequences for function.

Key Terms

Denaturation: Loss of 3D structure and function.
Factors: Temperature, pH, heavy metals, etc.

Step-by-Step Guidance

Define denaturation in the context of proteins and enzymes.
List common factors that can cause denaturation.
Explain the effect on enzyme activity.

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Q22. How does temperature generally affect enzyme activity?

Background

Topic: Enzyme Kinetics

This question tests your understanding of the relationship between temperature and enzyme function.

Key Terms

Optimal temperature
Denaturation at high temperatures

Step-by-Step Guidance

Describe how enzyme activity changes as temperature increases from low to optimal.
Explain what happens if the temperature exceeds the optimal range.
Relate this to the concept of denaturation.

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Q23. Distinguish between aerobic and anaerobic processes (which require oxygen?).

Background

Topic: Cellular Respiration

This question tests your understanding of the difference between processes that require oxygen and those that do not.

Key Terms

Aerobic: Requires oxygen.
Anaerobic: Does not require oxygen.

Step-by-Step Guidance

Define aerobic and anaerobic processes.
Give examples of each (e.g., cellular respiration vs. fermentation).
State the role of oxygen in each process.

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Q24. What does the presence of bubbles in a fermentation tube indicate?

Background

Topic: Fermentation and Gas Production

This question tests your understanding of how fermentation is detected in lab experiments.

Key Terms

Fermentation tube
CO2 production

Step-by-Step Guidance

Explain what is being measured in a fermentation tube experiment.
Describe what the bubbles represent (gas produced).
Relate this to the metabolic process occurring (e.g., fermentation of sugars).

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Q25. Describe the role of ATP (and nucleotides) in cellular energy transfer.

Background

Topic: Cellular Energy

This question tests your understanding of how ATP functions as the energy currency of the cell and the role of nucleotides.

Key Terms

ATP: Adenosine triphosphate
Nucleotide: Building block of ATP

Step-by-Step Guidance

Describe the structure of ATP and its relation to nucleotides.
Explain how ATP stores and releases energy.
Discuss the importance of ATP in cellular processes.

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Q26. How many valence electrons does carbon have and how many covalent bonds can it form?

Background

Topic: Atomic Structure of Carbon

This question tests your knowledge of basic chemistry as it relates to carbon's bonding properties.

Key Terms

Valence electrons
Covalent bonds

Step-by-Step Guidance

Recall the atomic number and electron configuration of carbon.
Determine the number of valence electrons in carbon.
State how many covalent bonds carbon can form based on its valence electrons.

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Q27. Why can carbon form isomers, including stereoisomers and enantiomers?

Background

Topic: Organic Molecule Diversity

This question tests your understanding of the structural versatility of carbon.

Key Terms

Isomer: Molecules with the same formula but different structures.
Stereoisomer: Same bonds, different spatial arrangement.
Enantiomer: Mirror-image isomers.

Step-by-Step Guidance

Define isomers, stereoisomers, and enantiomers.
Explain how carbon's bonding properties allow for these variations.
Give an example of each type.

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Q28. What are functional groups and why are they important in organic molecules?

Background

Topic: Organic Chemistry

This question tests your understanding of how functional groups affect the properties of organic molecules.

Key Terms

Functional group: Specific group of atoms within a molecule responsible for characteristic reactions.

Step-by-Step Guidance

Define what a functional group is.
Explain how functional groups influence chemical properties and reactivity.
List common functional groups found in biological molecules.

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Q29. Name common functional groups (e.g., hydroxyl, carboxyl, amino, phosphate, sulfhydryl) and their properties.

Background

Topic: Functional Groups in Biology

This question tests your ability to identify and describe the properties of common functional groups.

Key Terms

Hydroxyl (-OH)
Carboxyl (-COOH)
Amino (-NH2)
Phosphate (-PO4)
Sulfhydryl (-SH)

Step-by-Step Guidance

List each functional group and its chemical structure.
Describe the properties each group imparts to molecules (e.g., polarity, acidity, reactivity).
Give an example of a biological molecule containing each group.

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Q30. Why are carbon compounds the basis of organic chemistry?

Background

Topic: Organic Chemistry Foundations

This question tests your understanding of why carbon is central to the chemistry of life.

Key Terms

Versatility
Covalent bonding
Structural diversity

Step-by-Step Guidance

Explain the unique properties of carbon that allow it to form a wide variety of compounds.
Discuss the importance of carbon's ability to form stable covalent bonds with many elements.
Relate this to the diversity of organic molecules found in living organisms.

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Practice Free-Response Example: Compare and contrast dehydration synthesis and hydrolysis reactions. Include the role of water in each.

Background

Topic: Macromolecule Synthesis and Breakdown

This question tests your ability to explain the processes that build and break down biological polymers.

Key Terms

Dehydration synthesis: Builds polymers, removes water.
Hydrolysis: Breaks polymers, adds water.

Step-by-Step Guidance

Define dehydration synthesis and hydrolysis.
Describe the role of water in each reaction.
Explain which process builds and which breaks down polymers.
Give an example of each in biological systems.