Biology Unit 1 Test

What is biology?

The study of living organisms.

What is biodiversity?

The variety of life at all levels, from genes to ecosystems.

What are the major properties of living organisms?

Reproduction, growth and development, response to environmental stimuli, energy processing/metabolism, regulation of the internal environment, evolutionary adaptation, and being made of cells.

What is reproduction?

The ability of living organisms to produce offspring.

What is metabolism?

The processing and transformation of energy.

What is homeostasis?

The regulation of an organism's internal environment.

What is evolutionary adaptation?

Changes in organisms over generations that help them survive and reproduce in their environment.

What are cells?

The basic units of life.

Approximately how many cells make up humans?

Over 30 trillion cells.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

Which domains contain prokaryotes?

Bacteria and Archaea.

Which domain contains eukaryotes?

Eukarya.

What are prokaryotes?

Organisms with relatively simple cells that do not have a membrane-bound nucleus.

What are eukaryotes?

Organisms whose cells have a membrane-bound nucleus and more complex cells.

What are characteristics of Bacteria?

diverse, widespread, abundant prokaryotes; most are harmless, many are beneficial, and some cause disease.

What are Archaea?

Prokaryotic organisms that are less abundant and often inhabit extreme or harsh environments.

What are extremophiles?

Organisms that live in extreme or harsh environments.

What are thermophiles?

Organisms adapted to high temperatures.

What are psychrophiles?

Organisms adapted to cold temperatures.

What are halophiles?

Organisms adapted to high-salt environments.

What are acidophiles?

Organisms adapted to acidic environments.

What are methanogens?

Archaea associated with producing methane.

What are the major groups within Eukarya

Protists, fungi, plants, and animals.

What are protists?

Generally single-celled eukaryotic organisms.

What do fungi do for nutrition?

They decompose organic waste.

How do plants obtain nutrition?

They are photosynthetic self-feeders.

How do animals obtain nutrition?

They are heterotrophic feeders that ingest food.

What are the five unifying themes of biology?

Life depends on the flow of information; evolution is the core theme; structure and function are related; life depends on the transfer and transformation of energy; life depends on interactions within and between systems.

What is an element?

A chemical substance that cannot be broken down into a different substance.

What is an atom?

The smallest unit that retains the properties of an element.

What are the three subatomic particles?

Protons, neutrons, and electrons.

What is the charge of a proton?

Positive.

What is the charge of a neutron?

Neutral.

What is the charge of an electron?

Negative.

Where are protons located?

In the nucleus.

Where are neutrons located?

In the nucleus.

Where are electrons located?

In electron shells around the nucleus.

What is the atomic number?

The number of protons in an atom.

What is atomic mass?

The number of protons plus the number of neutrons in the nucleus.

What are isotopes?

Variations of an element that have different numbers of neutrons.

What is radioactivity?

The process in which an unstable atomic nucleus breaks down and releases radiation.

Why can radiation be dangerous?

It can damage atoms and cause mutations in DNA.

How is radiation used to treat cancer?

Radiation can damage the DNA of cancer cells and kill them, although healthy cells can also be damaged.

What is radiocarbon dating?

A method that uses radioactive isotopes, such as C-14, to estimate the age of organic material.

What is the approximate limit of carbon dating?

About 60,000 years.

What is a chemical bond?

An attractive force between atoms.

What is a chemical reaction?

A process in which reactant molecules are transformed into products by forming or breaking bonds.

What is a molecule?

A group of two or more atoms held together by chemical bonds.

What are the four types of chemical interactions important in biology?

Covalent bonds, ionic bonds, hydrogen bonds, and van der Waals forces.

What is a covalent bond?

A bond in which atoms share one or more pairs of electrons.

What is a nonpolar covalent bond?

electrons are shared EQUALLY

What is a polar covalent bond?

electrons are shared UNEQUALLY

What determines whether a covalent bond is polar or nonpolar?

The difference in electronegativity between the atoms.

What is electronegativity?

An atom's attraction or affinity for electrons.

What is the electronegativity difference for a nonpolar covalent bond?

Less than 0.5.

What is the electronegativity difference for a polar covalent bond?

Between 0.5 and 1.6.

What is an ionic bond?

A bond formed when an electron is transferred from one atom to another and the resulting ions attract each other.

What is the electronegativity difference associated with an ionic bond in the notes?

2 or greater.

What is a hydrogen bond?

An attraction between partial positive and negative regions of polar molecules.

How strong are hydrogen bonds compared with covalent and ionic bonds?

They are weaker.

What are van der Waals forces?

Weak interactions between molecules with slight positive and negative charges.

Which type of interaction is the weakest?

Van der Waals forces.

What is the valence shell?

The outermost electron shell of an atom.

What role do valence electrons play?

They are involved in forming chemical bonds.

What is the octet rule?

Atoms are most stable when their valence shell contains eight electrons.

Why is carbon important to organic molecules?

Its ability to form four covalent bonds allows it to create many unique structures.

Why is water a polar molecule?

Oxygen is more electronegative than hydrogen, so electrons are shared unequally.

Where is the partial negative charge in a water molecule?

Near the oxygen atom.

Where are the partial positive charges in a water molecule?

Near the hydrogen atoms.

What causes hydrogen bonds between water molecules?

Attraction between the partial positive and negative regions of different water molecules.

What is cohesion?

The tendency of water molecules to stick to each other.

What is adhesion?

The tendency of water to stick to other surfaces.

How do cohesion and adhesion help plants?

They help transport water and nutrients through plants.

What is surface tension?

The tendency of the surface of water to resist being broken due to cohesion between water molecules.

What is high specific heat?

The relatively large amount of energy required to raise water's temperature by 1°C.

Why is high specific heat important?

Water can absorb or release large amounts of heat with relatively little change in temperature.

What is heat of vaporization?

The energy required to break hydrogen bonds and change liquid water into water vapor.

Why does evaporation cool things?

Energy is required to break hydrogen bonds and turn liquid water into gas.

Why does ice float?

Solid water is less dense than liquid water because hydrogen bonds hold molecules in a less tightly packed arrangement.

Why is floating ice important?

Ice can act as an insulator in cold environments.

What is a solute?

A substance that is dissolved.

What is a solvent?

The substance that does the dissolving.

What is a solution?

A combination of a solute and a solvent.

Why is water called the solvent of life?

It can dissolve more substances than any other liquid and helps cells move and absorb nutrients.

What does pH measure?

The relative amount of hydrogen ions (H+) and hydroxide ions (OH-) in a solution.

Low pH (0-6)

acidic

High pH (8-14)

basic

Is the pH scale linear or logarithmic?

Logarithmic.

What does each pH unit represent?

A 10-fold change in the concentration of H+.

Which is more acidic, pH 6 or pH 8?

pH 6.

How much more acidic is pH 6 than pH 8?

100 times more acidic.

What is the approximate optimum pH of the human body?

About 7.4.

What is the neutral pH of water?

About 7.

Why is stable pH important?

Changes in acidity or alkalinity can denature proteins and interfere with their functions.

Why is stomach acid useful?

Its low pH helps denature proteins and destroys many harmful bacteria and parasites.

What is a buffer?

A molecule that can release or absorb H+ to help keep pH steady.

What buffer do the kidneys produce to help maintain blood pH?

Bicarbonate.

What is metabolic acidosis?

A condition involving blood becoming too acidic when buffering capacity is exceeded.

What are macromolecules?

Large molecules composed of multiple subunits.

What is a polymer?

A molecule composed of many repeating subunits.