Biology: Key Concepts, Cell Structure, and Biochemical Processes

Science

A process used to ask questions about the natural world, develop testable explanations, and analyze data

Observation

The act of gathering information using senses or tools

Quantitative observation

Observations based on numbers or measurements

Qualitative observation

Observations based on descriptions like color, texture, or shape

Hypothesis

A specific, testable explanation for an observation

Independent variable

The variable that is changed or manipulated

Dependent variable

The variable that is measured or responding

Control group

The group that does not receive the experimental treatment

Experimental group

The group that receives the treatment being tested

Conclusion

A statement that explains whether the data supports the hypothesis

Scientific theory

A well-supported explanation of natural phenomena

Scientific law

A statement that predicts what will happen under certain conditions

Cell

The smallest unit of life

Unicellular

Made of one cell

Multicellular

Made of multiple cells

Sexual reproduction

Reproduction using DNA from two parents

Asexual reproduction

Reproduction using DNA from one parent

DNA

The universal genetic code found in all living things

Growth and development

Increase in size and changes over time

Response to environment

Ability to react to stimuli

Homeostasis

Maintaining a stable internal environment

Evolution

Change over time in populations, not individuals

Metabolism

All chemical reactions needed to maintain life

Acid

Substance that produces H+ ions in water (pH < 7)

Base

Substance that produces OH- ions in water (pH > 7)

Surface tension

The ability of water to resist breaking due to cohesion

Density anomaly of water

Ice is less dense than liquid water

Specific heat

Amount of energy needed to change a substance's temperature

Cohesion

Water molecules sticking to each other

Adhesion

Water molecules sticking to other substances

Capillary action

Movement of water through narrow spaces

Heat of vaporization

Energy required to change liquid water into gas

Universal solvent

Water's ability to dissolve many substances

Carbon

Element that forms stable bonds and diverse structures

Biomolecule

Organic molecules found in living organisms

Carbohydrate

Biomolecule used for short-term energy

Monosaccharide

Simple sugar monomer

Polysaccharide

Complex carbohydrate polymer

Lipid

Biomolecule used for long-term energy and insulation

Protein

Biomolecule made of amino acids

Amino acid

Monomer of proteins

Nucleic acid

Biomolecule that stores genetic information

Nucleotide

Monomer of nucleic acids

Dehydration synthesis

Process that builds polymers by removing water

Hydrolysis

Process that breaks polymers using water

Enzyme

Protein that speeds up chemical reactions

Active site

Area of enzyme where substrate binds

Substrate

Reactant an enzyme acts on

Activation energy

Energy needed to start a reaction

Competitive inhibitor

Molecule that competes for the active site

Noncompetitive inhibitor

Molecule that changes enzyme shape

Denaturation

Loss of enzyme shape due to heat or pH

Cell theory

All living things are made of cells

Prokaryote

Cell without a nucleus

Eukaryote

Cell with a nucleus

Cell membrane

Controls what enters and exits the cell

Fluid mosaic model

Describes flexible membrane structure

Phospholipid bilayer

Main structure of cell membrane

Diffusion

Movement from high to low concentration

Facilitated diffusion

Diffusion using transport proteins

Osmosis

Diffusion of water across a membrane

Active transport

Movement against gradient using energy

Endocytosis

Cell taking materials in

Exocytosis

Cell releasing materials out

Nucleus

Control center of the cell

Ribosome

Site of protein synthesis

Rough ER

Organelle that makes proteins

Smooth ER

Organelle that makes lipids and detoxifies

Golgi apparatus

Modifies and ships proteins

Mitochondria

Produces ATP energy

Chloroplast

Site of photosynthesis

Lysosome

Breaks down waste and old organelles

Vacuole

Stores water, food, and waste

Cytoskeleton

Provides structure and movement

ATP

Main energy molecule of the cell

Aerobic

Requires oxygen

Anaerobic

Does not require oxygen

Cellular respiration

Process of making ATP from glucose

Glycolysis

First step of respiration, occurs in cytoplasm

Krebs cycle

Second step, occurs in mitochondrial matrix

Electron transport chain

Final step producing most ATP

Fermentation

ATP production without oxygen

Photosynthesis

Process of converting light energy into glucose

Light reactions

First stage of photosynthesis

Calvin cycle

Second stage of photosynthesis

Chlorophyll

Pigment that absorbs light energy

Autotroph

Organism that makes its own food

Heterotroph

Organism that gets energy from other organisms

Reactants

Substances used in a reaction

Products

Substances made in a reaction