A.p bio 🧪 UNIT 1 CHEMISTRY OF LIFE — TEST CRAM Q&A
🟣 TOPIC 1: BIOLOGY REVIEW & STATISTICS
Experimental Design
Q: What is the independent variable?
A: The variable the scientist changes/manipulates.
Q: What is the dependent variable?
A: The variable that is measured/observed.
Q: Easy way to remember independent vs. dependent?
A: Independent = I change it. Dependent = data I collect.
Q: In an experiment, fertilizer concentration is changed and plant height is measured. What is the independent variable?
A: Fertilizer concentration.
Q: What is the dependent variable?
A: Plant height.
Q: What are constants?
A: Things kept the same for every experimental group.
Q: What is a control group?
A: A group used as a comparison/baseline.
Q: What is a positive control?
A: A group that should produce a known positive result.
Q: What is a negative control?
A: A group that should produce no response/result.
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Data & Statistics
Q: What is qualitative data?
A: Descriptive data that isn’t measured numerically. Example: color, texture, smell.
Q: What is quantitative data?
A: Numerical/measurable data. Example: 15 cm, 20°C, 5 grams.
Q: What is the mean?
A: The average: add all values and divide by the number of values.
Q: What is the median?
A: The middle value when data is arranged from least to greatest.
Q: What is the mode?
A: The value that occurs most often.
Q: What is the range?
A: Highest − lowest.
Q: What does standard deviation tell you?
A: How spread out the data is around the mean.
Q: Small standard deviation means what?
A: Data points are close together/consistent.
Q: Large standard deviation means what?
A: Data points are more spread out/variable.
Q: If Group A and Group B have similar means, but Group A has a much smaller standard deviation, what does that mean?
A: Group A’s data is more consistent and clustered around the mean.
Q: What is SEM?
A: Standard error of the mean; it estimates how accurately the sample mean represents the population mean.
Q: What does a small SEM mean?
A: The mean is more precise/reliable.
Q: What do error bars show?
A: The amount of variation or uncertainty around a mean, depending on what the graph specifies.
Q: What should you look for when reading graphs?
A: Specific data points, trends, patterns, increases/decreases, and relationships between variables.
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💧 TOPIC 2: STRUCTURE OF WATER & HYDROGEN BONDING
Q: Why is water polar?
A: Oxygen is more electronegative than hydrogen, so oxygen becomes partially negative and hydrogen becomes partially positive.
Q: What does δ− mean?
A: Partial negative charge.
Q: What does δ+ mean?
A: Partial positive charge.
Q: What type of bond holds the H and O together inside one water molecule?
A: Covalent bond.
Q: What type of attraction occurs between different water molecules?
A: Hydrogen bonds.
Q: What causes water’s cohesion?
A: Hydrogen bonding between water molecules.
Q: What is cohesion?
A: Water molecules sticking to other water molecules.
Q: What is adhesion?
A: Water sticking to other surfaces/materials.
Q: What causes surface tension?
A: Cohesion/hydrogen bonding between water molecules at the surface.
Q: What is capillary action?
A: Water moving upward through a narrow space because of cohesion + adhesion.
Q: Why can water move upward through plants?
A: Hydrogen bonding creates cohesion between water molecules, while adhesion helps water interact with the plant’s xylem walls, allowing capillary action.
Q: Which interaction is primarily responsible for water cohesion?
A: Hydrogen bonds.
Q: What is a solute?
A: The substance being dissolved.
Q: What is a solvent?
A: The substance that does the dissolving.
Q: What is a solution?
A: A solute + solvent mixture.
⭐ MUST KNOW:
Polarity → hydrogen bonding → cohesion/adhesion → capillary action → water movement in plants
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🧬 TOPIC 2: ELEMENTS OF LIFE
Q: Why is carbon so important to life?
A: Carbon has 4 valence electrons, allowing it to form four stable covalent bonds and create many different structures.
Q: Why can carbon create such a huge diversity of molecules?
A: It can bond with itself and many other elements, creating chains, rings, branches, and complex structures.
Q: What four major macromolecules are built from carbon?
A: Carbohydrates, proteins, lipids, and nucleic acids.
Q: What element is especially important in amino acids and nitrogenous bases?
A: Nitrogen.
Q: What element is found in nucleic acids and certain lipids?
A: Phosphorus.
Functional Groups
Q: What is a functional group?
A: A group of atoms that gives an organic molecule specific chemical properties and behaviors.
Q: What are the major functional groups you need to know?
A: Hydroxyl, carbonyl, carboxyl, amino, and phosphate.
Q: What is a hydroxyl group?
A: –OH
Q: What is a carboxyl group?
A: –COOH
Q: What is an amino group?
A: –NH₂
Q: What is a phosphate group?
A: –PO₄ group.
Q: What is a carbonyl group?
A: A carbon double-bonded to oxygen: C=O.
Q: What is a hydrocarbon?
A: A molecule made only of carbon and hydrogen.
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🔗 TOPIC 3: INTRODUCTION TO BIOLOGICAL MACROMOLECULES
Q: What is a monomer?
A: A small building block that can join with others.
Q: What is a polymer?
A: A large molecule made from repeating monomers.
Q: What are the four major biological macromolecules?
A: Carbohydrates, proteins, lipids, nucleic acids.
Q: What is dehydration synthesis?
A: A process that joins monomers by forming a covalent bond and removing H₂O.
Q: What is hydrolysis?
A: A process that breaks covalent bonds by adding H₂O.
🧠 REMEMBER:
Dehydration = take water OUT → build
Hydrolysis = add water → break
Q: Which process joins monomers to form a polymer?
A: Dehydration synthesis.
Q: Which process breaks polymers apart?
A: Hydrolysis.
Q: What happens to water during dehydration synthesis?
A: Water is removed/released.
Q: What happens to water during hydrolysis?
A: Water is added.
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🍞 TOPIC 4: PROPERTIES OF BIOLOGICAL MACROMOLECULES
Carbohydrates
Q: What is a monosaccharide?
A: A single sugar monomer.
Q: What is a polysaccharide?
A: A carbohydrate polymer made of many sugar units.
Q: What is starch used for?
A: Energy storage in plants.
Q: What is glycogen used for?
A: Energy storage in animals.
Q: What is cellulose used for?
A: Structural support in plant cell walls.
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Proteins
Q: What are proteins made of?
A: Amino acids.
Q: What is the monomer of a protein?
A: Amino acid.
Q: What part of an amino acid varies between amino acids?
A: The R group.
Q: Why are R groups important?
A: Their different properties affect how a protein folds and functions.
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Lipids
Q: Are lipids generally polar or nonpolar?
A: Mostly nonpolar/hydrophobic.
Q: What does hydrophobic mean?
A: Water-fearing; doesn’t mix well with water.
Q: What does hydrophilic mean?
A: Water-loving; interacts with water.
Q: What is the difference between saturated and unsaturated fatty acids?
A: Saturated = no C=C double bonds. Unsaturated = one or more C=C double bonds.
Q: Which fatty acid has more bends/kinks?
A: Unsaturated fatty acid.
Q: Why do unsaturated fatty acids have kinks?
A: Their double bonds bend the carbon chain.
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Phospholipids
Q: What two types of regions does a phospholipid have?
A: A polar hydrophilic head and nonpolar hydrophobic tails.
Q: Why are phospholipids important in cells?
A: They form the cell membrane bilayer.
Q: Why do phospholipids form a bilayer?
A: The hydrophilic heads face the watery environments while the hydrophobic tails face inward away from water.
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Nucleic Acids
Q: What do nucleic acids do?
A: They store and transmit biological information.
Q: What is the monomer of nucleic acids?
A: Nucleotide.
Q: What are nucleotides made of?
A: A 5-carbon sugar + phosphate group + nitrogenous base.
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🧩 TOPIC 5: STRUCTURE & FUNCTION OF BIOLOGICAL MACROMOLECULES
Protein Structure
Q: What determines a protein’s primary structure?
A: The sequence of amino acids.
Q: What is secondary protein structure?
A: Local folding into structures such as alpha helices and beta sheets, stabilized by hydrogen bonds.
Q: What is tertiary structure?
A: The overall 3D shape of one polypeptide.
Q: What is quaternary structure?
A: Multiple polypeptide chains/subunits working together.
⭐ KNOW THIS ORDER:
Primary → Secondary → Tertiary → Quaternary
Q: Why can changing one amino acid affect protein function?
A: It can change interactions between amino acids, which can change the protein’s shape, potentially changing its function.
Q: What is denaturation?
A: When a protein loses its normal shape, causing it to lose or reduce its function.
Q: What can cause protein denaturation?
A: Things such as high temperature or extreme pH.
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DNA Structure
Q: What does antiparallel mean?
A: The two DNA strands run in opposite directions: one 5’ → 3’ and the other 3’ → 5’.
Q: Why is DNA directionality important?
A: DNA strands have specific 5’ and 3’ ends, which determines how they are read and copied.
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Carbohydrate Structure
Q: Why can two carbohydrates made from similar sugar monomers have different functions?
A: Their monomers can have different arrangements, bonding, branching, and structures, which changes their properties and functions.
Q: Example of this?
A: Starch and cellulose are both made from glucose, but their different bonding/arrangements give them different functions.
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🧬 TOPIC 6: NUCLEIC ACIDS
Q: What are the three parts of a nucleotide?
A: 5-carbon sugar + phosphate group + nitrogenous base.
Q: What sugar is found in DNA?
A: Deoxyribose.
Q: What sugar is found in RNA?
A: Ribose.
Q: What nitrogenous base is found in DNA but not RNA?
A: Thymine (T).
Q: What nitrogenous base is found in RNA instead of thymine?
A: Uracil (U).
Q: Is DNA usually single- or double-stranded?
A: Double-stranded.
Q: Is RNA usually single- or double-stranded?
A: Single-stranded.
Q: What does DNA store?
A: Genetic/biological information.
Q: What connects nucleotides together?
A: Covalent bonds form the sugar-phosphate backbone.
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🧬 Base Pairing
Q: What does A pair with in DNA?
A: T
Q: What does T pair with?
A: A
Q: What does C pair with?
A: G
Q: What does G pair with?
A: C
RNA:
A ↔ U
C ↔ G
Q: If one DNA strand is 5’-ACGTAC-3’, what is the complementary strand?
A: 3’-TGCATG-5’
Q: Why is it written 3’ → 5’?
A: Because DNA strands are antiparallel.
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🔥 UNIT 1 BIG CONNECTIONS — YOUR TEACHER WILL LOVE THESE
Q: Explain the water connection.
A: Water’s polarity causes hydrogen bonding, which produces properties like cohesion and adhesion that are important for biological functions such as water movement through plants.
Q: Explain the carbon connection.
A: Carbon’s four valence electrons allow it to form many covalent bonds, creating the huge diversity of biological molecules.
Q: Explain the macromolecule connection.
A: Monomers join → polymers/macromolecules form → their structure determines their properties and function.
Q: Explain the protein connection.
A: Amino acid sequence → protein shape → protein function.
Q: Explain the DNA connection.
A: Nucleotide sequence → biological/genetic information.
Q: Explain the experiment connection.
A: Experimental design → data → analysis → evidence → biological conclusion.
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🚨 15 QUESTIONS YOU SHOULD BE ABLE TO ANSWER WITHOUT LOOKING
What is the independent variable?
→ What you change.
What is the dependent variable?
→ What you measure.
Small standard deviation means…?
→ Data is consistent/close together.
Why is water polar?
→ Oxygen is more electronegative than hydrogen.
What causes cohesion?
→ Hydrogen bonding.
What causes capillary action?
→ Cohesion + adhesion.
Why is carbon so versatile?
→ Four valence electrons.
What joins monomers?
→ Dehydration synthesis.
What breaks polymers?
→ Hydrolysis.
Protein monomer?
→ Amino acid.
Nucleic acid monomer?
→ Nucleotide.
Unsaturated fatty acids have what?
→ Double bonds and kinks.
What determines protein shape?
→ Amino acid sequence/interactions.
DNA sugar/base?
→ Deoxyribose + thymine.
DNA strands are…?
→ Double-stranded and antiparallel.
🧠 LAST-MINUTE MEMORY CHAIN
Memorize this exact chain:
Water:
POLAR → H-BONDS → COHESION/ADHESION → CAPILLARY ACTION
Macromolecules:
MONOMER → DEHYDRATION → POLYMER
Breaking:
POLYMER → HYDROLYSIS → MONOMERS
Protein:
AMINO ACID SEQUENCE → SHAPE → FUNCTION
DNA:
NUCLEOTIDE SEQUENCE → INFORMATION
Experiment:
INDEPENDENT → DEPENDENT → DATA → EVIDENCE → CONCLUSION
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