BIO101 Ch1&2

What characteristics define life?

Organization, energy use, internal constancy, reproduction and development, and evolution

What does it mean that life is organized?

Living things have ordered structures from atoms to organisms

What is the smallest level of biological organization?

Atoms

Atoms combine to form what?

Molecules

Molecules form what structures inside cells?

Organelles

Organelles make up what?

Cells

What is a cell?

The smallest unit of life

In multicellular organisms, cells form what?

Tissues

Tissues combine to form what?

Organs

Organs work together to form what?

Organ systems

Organ systems make up what?

A multicellular organism

What is an organism?

An individual living thing made of one or more cells

What is a population?

A group of individuals of the same species in one area

What is a community?

All the populations of different species in an area

What is an ecosystem?

Living communities plus their nonliving environment

What is the biosphere?

All ecosystems on Earth

What are emergent properties?

Characteristics that arise from interactions among parts of an organism

Why does life require energy?

To maintain organization and carry out functions

What are primary producers?

Organisms that make their own food using energy from the environment

What are consumers?

Organisms that eat other organisms

What are decomposers?

Organisms that recycle nutrients back to the environment

Why do ecosystems require constant energy input?

Energy is lost as heat, usually replenished by the sun

What is homeostasis?

Maintaining stable internal conditions despite external changes

Why is homeostasis important?

It allows organisms to survive in changing environments

How can organisms reproduce?

Asexually, sexually, or both

What is asexual reproduction?

Reproduction that produces genetically identical offspring

What is sexual reproduction?

Reproduction that combines DNA from two parents

Why does sexual reproduction increase diversity?

It mixes and scrambles genetic information

What is development?

Growth and changes as an organism matures

What is evolution?

Change in populations over generations

What is natural selection?

Process where organisms with beneficial adaptations survive and reproduce more

What are adaptations?

Traits that increase survival and reproduction

What does evolution explain about life?

Common ancestry and diversity of species

What is taxonomy?

The science of classifying organisms

What is a species?

A group of organisms that can interbreed

What is a genus?

A group of closely related species

What are the two broadest taxonomic levels?

Domain and kingdom

What are the three domains of life?

Bacteria, Archaea, and Eukarya

What is scientific inquiry?

Using evidence to evaluate ideas about the natural world

What is the scientific method?

A systematic way to test explanations using evidence

What is a hypothesis?

A testable explanation for observations

What are predictions?

Specific expected outcomes based on a hypothesis

What happens after scientific results are collected?

They may be published

What is peer review?

Evaluation of scientific work by other scientists

What is an experiment?

A controlled test of a hypothesis

What is an independent variable?

The factor manipulated by the investigator

What is a dependent variable?

The factor measured in an experiment

What are standardized variables?

Conditions kept constant for all subjects

What is a control group?

A group that does not receive the treatment

What is a placebo?

A fake treatment with no active effect

What is a double-blind experiment?

Neither subjects nor researchers know who receives the treatment

Why is large sample size important?

It increases reliability of results

What does statistically significant mean?

Results are unlikely due to chance

What do large overlapping error bars indicate?

Results are likely due to chance

What do small non-overlapping error bars indicate?

A real effect of the independent variable

How does sample size affect significance?

Larger samples increase significance

How does variation in data affect significance?

Lower variation increases significance

What is a scientific theory?

A broad, well-supported explanation

How does a theory differ from a hypothesis?

A theory is broader and more accepted

Can scientific theories change?

Yes, with new evidence

What are limitations of science?

It cannot answer questions without testable hypotheses

What do all substances contain?

All substances contain matter and energy, the ability to do work.

What are elements?

Elements are pure substances that all matter can be broken down into.

What are bulk elements?

Bulk elements are elements required in large quantities for life, such as carbon, hydrogen, oxygen, and nitrogen.

What are trace elements?

Trace elements are elements required by organisms in very small amounts.

What is an atom?

An atom is the smallest unit of an element.

What particles make up the nucleus of an atom?

Protons and neutrons make up the nucleus of an atom.

What charge do electrons have and where are they found?

Electrons have a negative charge and surround the nucleus.

How are elements organized in the periodic table?

Elements are organized by atomic number, which is the number of protons.

What is an ion?

An ion is an atom that has gained or lost electrons.

What is an isotope?

Isotopes are forms of an element that differ in the number of neutrons.

What is a radioactive isotope?

A radioactive isotope is an unstable isotope.

What does atomic weight represent?

Atomic weight reflects the average mass number of an element’s isotopes, weighted by natural abundance.

What is a molecule?

A molecule is two or more atoms joined together.

What is a compound?

A compound is a molecule made of atoms from different elements.

What are orbitals?

Orbitals are regions of space where electrons are most likely to be found.

What are energy shells?

Energy shells are groups of orbitals around an atom.

What drives atoms to form chemical bonds?

Atoms form chemical bonds to fill their valence shell with electrons.

What is electronegativity?

Electronegativity is an atom’s ability to attract electrons.

What is an ionic bond?

An ionic bond is the attraction between oppositely charged ions.

How do ions form?

Ions form when one atom gains or loses electrons.

What is a covalent bond?

A covalent bond forms when atoms share electrons.

What is a nonpolar covalent bond?

A nonpolar covalent bond shares electrons equally.

What is a polar covalent bond?

A polar covalent bond forms when electrons are shared unequally, creating partial charges.

What causes partial charges in polar molecules?

Differences in electronegativity cause partial positive and negative charges.

What is a hydrogen bond?

A hydrogen bond is an attraction between opposite partial charges on nearby molecules.

What is cohesion?

Cohesion is the tendency of water molecules to stick to each other.

What is adhesion?

Adhesion is the tendency of water molecules to stick to other substances.

What is a solution?

A solution consists of a solute dissolved in a solvent.

What substances dissolve easily in water?

Hydrophilic (polar or charged) substances dissolve easily in water.

What substances do not dissolve in water?

Hydrophobic (nonpolar) substances do not dissolve in water.

How does water help regulate temperature?

Water resists temperature change and evaporation, helping stabilize temperatures.

Why does ice float in water?

Ice floats because it is less dense than liquid water.

What are reactants?

Reactants are the starting materials in a chemical reaction.

What are products?

Products are the substances formed by a chemical reaction.

Where do most biochemical reactions occur?

Most biochemical reactions occur in a watery solution.

What does neutral pH mean?

Neutral pH means equal concentrations of H⁺ and OH⁻ ions.

What does an acid do to a solution?

An acid increases the concentration of H⁺ ions.

What does a base do to a solution?

A base decreases H⁺ or increases OH⁻ ions.

What is the pH of pure water?

Pure water has a pH of 7.