Lecture Notes Flashcards: Chi-Square, Graphs, Water, Macromolecules

Forty-five Q&A flashcards covering Chi-Square statistics, graphing conventions, water chemistry, and major biomolecules.

What is the formula for Chi-Square?

χ² = Σ((observed - expected)² / expected).

When is Chi-Square used in biology?

To determine if observed results significantly differ from expected results (e.g., genetics ratios, experiments).

What is a degree of freedom (df) in Chi-Square?

df = number of categories - 1.

How do you know if results are statistically significant in Chi-Square?

Compare the calculated χ² to the critical value at p = 0.05; if χ² is greater, reject the null hypothesis.

What is the null hypothesis in Chi-Square?

There is no significant difference between observed and expected results.

What type of graph should you use for continuous data?

Line graph (shows trends over time or continuous values).

What type of graph should you use for categorical data?

Bar graph (comparing discrete groups).

How should axes be labeled on graphs?

Independent variable on the x-axis, dependent variable on the y-axis, with units.

What does R² show in a best-fit line graph?

How well the line fits the data (closer to 1 = better fit).

Why are error bars important in graphs?

They show variability (e.g., standard error) and help indicate whether differences are statistically significant.

What is dehydration synthesis?

A reaction that removes water to join monomers into polymers (condensation reaction).

What is hydrolysis?

A reaction that adds water to break polymers into monomers.

Which process builds macromolecules?

Dehydration synthesis.

Which process digests macromolecules?

Hydrolysis.

Give an example of dehydration synthesis in biology.

Forming a peptide bond between amino acids.

Give an example of hydrolysis in biology.

Digesting starch into glucose using enzymes.

What molecules are always involved in dehydration and hydrolysis reactions?

Hydrogen (H) and hydroxyl group (OH) from water.

Why are enzymes important in dehydration and hydrolysis reactions?

They catalyze these reactions, making them biologically possible.

What type of bond holds water molecules together?

Polar covalent bonds (within a water molecule).

What type of bond forms between different water molecules?

Hydrogen bonds.

Why is water polar?

Oxygen is more electronegative, pulling electrons toward itself and giving O a partial negative charge and H partial positive charges.

What property of water allows cohesion?

Hydrogen bonding between water molecules.

What property of water allows adhesion?

Hydrogen bonds with other polar or charged surfaces.

Why does water have a high specific heat?

Hydrogen bonds absorb heat before breaking, resisting temperature changes.

Why is ice less dense than liquid water?

Hydrogen bonds arrange water molecules into a crystalline structure, making ice less dense.

Why is water called the 'universal solvent'?

Because it dissolves many substances due to its polarity and ability to surround ions and polar molecules.

How does water help in homeostasis?

Maintains stable body temperatures and dissolves nutrients/wastes for transport.

What is surface tension and why does water have high surface tension?

Cohesion of water molecules at the surface due to hydrogen bonding.

What is a nonpolar covalent bond?

Electrons are shared equally between atoms (e.g., O2, CH4).

What is an ionic bond?

Electrons are transferred from one atom to another, forming charged ions (e.g., NaCl).

How can you tell if a molecule is polar?

Look for electronegativity differences and an asymmetric shape that creates dipole moments.

Why are polar/nonpolar properties important in biology?

They influence solubility, membrane structure (phospholipids), and protein folding.

What are the four classes of macromolecules?

Carbohydrates, lipids, proteins, nucleic acids.

What are the monomers of carbohydrates?

Monosaccharides (simple sugars like glucose).

What are the polymers of carbohydrates?

Polysaccharides (starch, glycogen, cellulose).

What is the function of carbohydrates?

Short-term energy storage and structural support.

What are the monomers of proteins?

Amino acids.

What bond links amino acids?

Peptide bonds (formed by dehydration synthesis).

What are the four protein structure levels?

Primary, secondary (α-helix, β-sheet), tertiary (3D folding), quaternary (multiple chains).

What determines protein shape and function?

The sequence and properties of amino acid R groups.

What are the monomers of nucleic acids?

Nucleotides (sugar, phosphate, nitrogenous base).

What bonds hold DNA strands together?

Hydrogen bonds between complementary bases (A-T, G-C).

What are the monomers of lipids?

Mostly glycerol + fatty acids (not always true polymers).

What is the function of lipids?

Long-term energy storage, membranes, insulation, hormones.

How are macromolecules related to hydrolysis/dehydration?

All macromolecules are built by dehydration synthesis and broken by hydrolysis.