Principles of bio Exam 1

Characteristics of life

Living things are made of cells, use energy, grow, reproduce, respond to environment, maintain homeostasis, and evolve.

Levels of biological organization

Atom, molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere.

Hypothesis

A testable prediction with the lowest certainty.

Theory

A well-supported explanation backed by evidence.

Law

Describes a natural pattern that always happens, having the highest certainty.

Independent variable

The variable that the scientist changes in an experiment.

Dependent variable

The variable that is measured in an experiment.

Scientific method steps

Observe, question, hypothesis, experiment, collect data, analyze, conclude, repeat.

Line graph

Used to show change over time.

Bar graph

Used to compare different groups.

Histogram

Used to show the distribution of data.

Matter

Anything that has mass and volume.

Elements

Pure substances made of one type of atom.

Atoms

The smallest unit of matter.

Atomic number

The number of protons in an atom.

Mass number

The sum of protons and neutrons in an atom.

Isotope

Atoms of the same element with different numbers of neutrons.

Radioactivity

The process of unstable nuclei releasing energy.

Ionic bond

A chemical bond that involves the transfer of electrons.

Covalent bond

A chemical bond formed by the sharing of electrons.

Polar molecule

A molecule with an unequal distribution of charges.

Nonpolar molecule

A molecule with an equal sharing of electrons.

Properties of water

Cohesion, adhesion, high heat capacity, universal solvent, ice floats, surface tension.

Acid

A substance with a pH between 0 and 6.

Base

A substance with a pH between 8 and 14.

Neutral

A substance with a pH of 7.

Dehydration reaction

A reaction that builds molecules by removing water.

Hydrolysis reaction

A reaction that breaks molecules using water.

Peptide bond

A bond that links amino acids together.

Why cells are small

Small size allows for efficient nutrient and waste exchange.

Prokaryotic cell

A cell type that lacks a nucleus and is typically simpler, such as bacteria.

Eukaryotic cell

A cell type that has a nucleus and is more complex, such as plant and animal cells.

Main organelles

Nucleus, mitochondria, ribosomes, ER, Golgi, lysosomes, chloroplasts.

Chloroplasts

Organelles in plants that conduct photosynthesis.

Mitochondria function

To produce ATP, the energy currency of the cell.

Diffusion

The movement of molecules from areas of high to low concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Active transport

The process that requires energy to move molecules from low to high concentration.

Exocytosis

The process by which a cell releases materials to the outside.

Endocytosis

The process by which a cell takes in materials from the outside.

Plasma membrane structure

Composed of a phospholipid bilayer with embedded proteins.

Selective permeability

Property that allows only certain substances to pass through a membrane.

Isotonic solution

A solution where water movement is equal in and out of the cell.

Hypertonic solution

A solution that causes water to leave the cell, leading to shrinkage.

Hypotonic solution

A solution that causes water to enter the cell, leading to swelling.

Types of membrane proteins

Transport, receptor, enzyme, recognition, and attachment proteins.

Fluid mosaic model

The model describing the cell membrane as flexible with proteins floating in the lipid bilayer.

Functions of membrane proteins

Includes transport, signaling, recognition, and enzyme activity.

Phospholipid structure

Consists of a hydrophilic head and hydrophobic tails that form a bilayer.

Passive transport

Movement from high to low concentration without energy use.

Osmosis definition

The diffusion of water across a membrane.

Tonicity terms

Hypertonic: cell shrinks, Hypotonic: cell swells, Isotonic: cell remains the same.

Animal vs. plant cells in hypertonic solution

Both types shrink; plant cells undergo plasmolysis.

Animal vs. plant cells in hypotonic solution

Animal cells burst; plant cells become turgid.

Facilitated diffusion

Transport using proteins without energy.

Active transport (distinction)

Transport that uses proteins and requires energy.