Principles of bio exam 1

Why is biology considered hierarchical?

Biology is studied at different levels of organization, from small/simple → large/complex, such as molecules → cells → organisms → ecosystems → biosphere.

What are the levels of biological organization in order?

Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere A M O C T O O O P C E B

What is biology?

The study of life.

Why is biology important?

Biology affects real-world issues including medicine, the environment, vaccines, antibiotic resistance, criminology/forensics, genetics, nutrition, and health. Biology affects everyday life.

What are the 7 properties/characteristics of life?

1. Organization

2. Regulation

3. Growth & development

4. Energy utilization

5. Response to stimuli

6. Reproduction

7. Evolution

What does organization mean?

living things are complex and organized.

Example: cells → tissues → organs → organ systems.

What is regulation/homeostasis?

The ability of an organism or cell to maintain a stable internal environment despite external changes.

🧠 Homeostasis = keeping things stable

What does growth and development mean?

Growth involves an increase in cell size, cell number, or both. Genetic information controls patterns of growth and development.

What does energy utilization mean?

Living things acquire and use materials and energy. Energy powers metabolism, which is the sum of chemical reactions in an organism.

What does response to stimuli mean?

Living things respond to changes in their internal or external environment.

Examples: light, sound, chemicals, touch, temperature, water.

What does reproduction mean?

Living things produce offspring through sexual or asexual reproduction. DNA is passed from parents to offspring.

What does evolution mean as a characteristic of life?

Populations change over long periods of time. Evolution accounts for both the unity and diversity of life.

What is natural selection?

A process that drives evolution in which individuals with favorable inherited traits tend to survive and reproduce more successfully.

What are the 3 important ideas behind natural selection?

Variation → Fitness → Heritability

• Variation: individuals differ

• Fitness: some traits help survival/reproduction

• Heritability: favorable traits can be passed to offspring

How does natural selection contribute to evolution?

Individuals with favorable inherited traits reproduce more, causing those traits to become more common in the population over generations. This results in evolutionary change.

🧠 Natural selection = mechanism; evolution = result

What is the scientific method?

A process scientists use to investigate questions about the natural world using observations, hypotheses, predictions, experiments, and evidence.

What are the basic steps of the scientific method?

Observation → Hypothesis → Prediction → Experiment → Results → Support or refute hypothesis

🧠 Observe → Explain → Predict → Test → Analyze

What is a hypothesis?

A testable explanation for an observation.

Does an experiment "prove" a hypothesis?

❌ No. Results can support or refute a hypothesis.

What is an atom?

The smallest unit of matter that retains the properties of an element.

What is an element?

A substance that cannot be broken down by chemical means and is defined by its number of protons.

What is a molecule?

Two or more atoms chemically bonded together.

Example: O₂ or H₂O.

What is a compound?

A molecule containing two or more different elements.

Example: H₂O.

What is the difference between a molecule and a compound?

Molecule: atoms bonded together.
Compound: different elements bonded together.

🧠 Every compound is a molecule, but not every molecule is a compound.

What are the 3 subatomic particles?

Particle	Charge	Location
Proton	+	Nucleus
Neutron	0	Nucleus
Electron	−	Outside nucleus

🧠 P = Positive, N = Neutral, E = Negative

What determines what element an atom is?

The number of protons.

What is atomic number?

The number of protons in an atom.

🧠 Atomic NUMBER = NUMBER of protons

What is atomic mass?

Approximately the number of protons + neutrons.

What are isotopes?

Atoms of the same element that have different numbers of neutrons.

🧠 Same protons, different neutrons.

What is an ionic bond?

A bond formed when electrons are transferred from one atom to another.

🧠 Ionic = GIVE/TAKE

What is a covalent bond?

A bond formed when atoms share electrons.

🧠 Covalent = SHARE

What is a hydrogen bond?

A weak attraction between molecules/parts of molecules involving a partially positive hydrogen and a partially negative atom.

🧠 Hydrogen = attraction

What is a polar covalent bond?

A covalent bond where electrons are shared unequally.

What is a nonpolar covalent bond?

A covalent bond where electrons are shared equally or nearly equally.

How do you remember ionic vs. covalent vs. hydrogen?

Ionic = TRANSFER

🤝 Covalent = SHARE

🧲 Hydrogen = ATTRACT

Why is water a polar molecule?

Water has an unequal distribution of electrons, giving it slightly positive and negative regions.

What is cohesion?

Water molecules stick to other water molecules.

🧠 COhesion = COming together

What is adhesion?

Water sticks to other substances/surfaces.

🧠 ADhesion = ADding to something else

Why is water's high specific heat important?

Water can absorb a lot of energy without a large temperature change, helping organisms and environments resist rapid temperature changes.

Why is water an excellent solvent?

Because of its polarity, water can dissolve many substances, allowing materials to move and participate in chemical reactions.

Why does ice float?

Ice is less dense than liquid water.

What are the 4 major groups of organic molecules?

🍞 Carbohydrates

🧈 Lipids

💪 Proteins

🧬 Nucleic acids

🧠 CLPN = Carbs, Lipids, Proteins, Nucleic acids

What is the main function of carbohydrates?

Primarily energy, including short-term energy and energy storage; some carbohydrates also provide structure.

What are examples of carbohydrates?

Glucose, fructose, starch, cellulose.

What are the building blocks/subunits of carbohydrates?

Monosaccharides.

Example: glucose.

What are the major functions of lipids?

Long-term energy storage, cell membranes, and hormones/steroids.

What are examples of lipids?

ats, oils, phospholipids, steroids.

What are the building blocks of proteins?

Amino acids.

🧠 Protein → Amino acids

What are the major functions of proteins?

Proteins can function as enzymes, structural components, transporters, receptors, and contractile proteins.

What are the 4 levels of protein structure?

1. Primary = amino acid sequence

2. Secondary = local folding

3. Tertiary = overall 3-D shape

4. Quaternary = multiple polypeptide chains

🧠 P → S → T → Q

"Please Study The Quiz"

What are nucleic acids?

Organic molecules involved in storing genetic information.

Examples: DNA and RNA.

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What are the subunits of nucleic acids?

Nucleotides.

🧠 Nucleic acid → Nucleotide

What are the 3 parts of a nucleotide?

Sugar + phosphate + nitrogenous base

What is dehydration synthesis?

A reaction that builds larger molecules by joining smaller molecules and removing water.

🧠 DEHYDRATION = water OUT = BUILD

What is hydrolysis?

A reaction that breaks larger molecules into smaller molecules by adding water.

🧠 HYDRO = water IN = BREAK

Which reaction builds biological molecules? Which breaks them?

🧱 Dehydration = BUILD

💥 Hydrolysis = BREAK

What is a triglyceride?

A lipid made of:

1 glycerol + 3 fatty acids

🧠 TRI = 3

What is a saturated fat?

A fatty acid with no carbon-carbon double bonds; saturated fats are generally solid at room temperature.

🧠 Saturated = Solid 🧈

What is an unsaturated fat?

A fatty acid with one or more carbon-carbon double bonds; unsaturated fats are generally liquid at room temperature.

🧠 Unsaturated = Oil 🫒

Saturated vs. unsaturated?

Saturated → no double bonds → usually solid

Unsaturated → one or more double bonds → usually liquid

What is a phospholipid?

A lipid with a polar phosphate-containing head and nonpolar fatty acid tails.

Which part of a phospholipid is polar?

The head.

🧠 Head = hydrophilic = likes water

Which part of a phospholipid is nonpolar?

The fatty acid tails.

🧠 Tails = hydrophobic = avoid water

What is the lipid bilayer?

A double layer of phospholipids that forms the basic structure of the plasma membrane.

How are phospholipids arranged in the plasma membrane?

Water

⬇

🟡🟡🟡🟡🟡 POLAR HEADS

🟣🟣🟣🟣🟣 NONPOLAR TAILS

🟣🟣🟣🟣🟣 NONPOLAR TAILS

🟡🟡🟡🟡🟡 POLAR HEADS

⬆

Water

🧠 HEADS FACE WATER — TAILS FACE EACH OTHER