General Biology: Basic Chemistry Quiz

Basic Chemistry Quiz

Fluoride

Is a common ingredient in Earth’s crust

Helps maintain healthy teeth

Fluoride prevents cavities by

Affecting the metabolism of oral bacteria

Promoting the replacement of lost minerals on the tooth surface

Take any biological system apart, and…

you eventually end up at the chemical level.

Matter

anything that occupies space and has mass.

Matter is found on the Earth in three physical states:

Solid

Liquid

Gas

Matter is composed of chemical elements.

Elements are substances that cannot be broken down into other

substances.

There are 92 naturally occurring elements on Earth.

How many elements are essential to life?

25

Four elements make up about 96% of the weight of the human body:

Oxygen

Carbon

Hydrogen

Nitrogen

Trace elements

Occur in smaller amounts

Are essential for life

An iodine deficiency causes…

goiter

Compounds

substances that contain two or more elements in a fixed ratio.

Common compounds include

NaCl (table salt)

H2O (water)

Each element consists of ___ kind of atom.

one

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

atom

proton

positively charged

electron

negatively charged

neutron

electrically neutral

Most atoms have protons and neutrons packed tightly into the ___.

nucleus

The ___ is the atom’s central core.

Electrons orbit the ___.

nucleus

The number of protons, the ___, determines which element it is.

atomic number

An atom’s ___ is the sum of the number of protons and neutrons.

mass number

___ is a measure of the amount of matter in an object.

Mass

___ are alternate mass forms of an element.

___ have the same number of protons and electrons, but they have a different number of neutrons.

Isotopes

The nucleus of a ___ decays, giving off particles and energy.

radioactive isotope

___s determine how an atom behaves when it encounters other atoms.

___s orbit the nucleus of an atom in specific electron shells.

The farther an ___ is from the nucleus, the greater its energy.

The number of ___s in the outermost shell determines the chemical properties of an atom.

electron

___ enable atoms to give up or acquire electrons to complete their outer shells.

Chemical reactions

Chemical reactions usually result in atoms

Staying close together

Being held together by chemical bonds

When an atom loses or gains electrons, it becomes ___.

electrically charged

Charged atoms are called

ions

___ are formed between oppositely charged ions.

Ionic bonds

A ___ forms when two atoms share one or more pairs of outer-shell electrons.

covalent bond

Atoms held together by covalent bonds form a

molecule

The number of covalent bonds an atom can form is ___ to the number of additional electrons needed to fill its outer shell.

equal

Water is a compound in which the electrons in its covalent bonds are shared unequally.

This causes water to be a ___, one with opposite charges on opposite ends.

polar molecule

The polarity of water results in weak electrical attractions between neighboring water molecules.

These interactions are called ___.

hydrogen bonds

Cells constantly rearrange molecules by breaking existing chemical bonds and forming new ones. Such changes in the chemical composition of matter are called ___.

chemical reactions

Chemical reactions include

1) ___, the starting materials

2) ___, the end materials

1) Reactants

2) Products

Why is the Earth habitable?

Abundance of water

The polarity of water molecules and the hydrogen bonding that results explain most of ___.

Water molecules stick together.

Water has a strong resistance to change in temperature.

Frozen water floats.

Water is a common solvent for life.

Water’s Life-Supporting Properties

Water molecules stick together as a result of hydrogen bonding.

This is called ___.

___ is vital for water transport in plants.

cohesion

___ is the measure of how difficult it is to stretch or break the surface of a liquid.

Surface tension

___ is the amount of energy associated with the movement of the atoms and molecules in a body of matter.

Heat

___ measures the intensity of heat.

Temperature

___ removes heat from the Earth and from organisms.

Evaporative cooling

A ___ is a liquid consisting of a homogeneous mixture of two or more substances.

solution

The dissolving agent is the ___.

solvent

The dissolved substance is the ___.

solute

When water is the solvent, the result is an ___.

aqueous solution

1) ___: Human brains shrink as we age.

2) ___: Can aerobic exercise slow or reverse brain loss?

3) ___: MRI scans would reveal differences between people who regularly exercised aerobically and those who did not.

1) Observation

2) Question

3) Hypothesis

1) ___: Brains of active people would shrink less than the brains of less active people.

2) ___: Twenty-nine people in their 60s and 70s exercised for three one-hour sessions per week. A control group of 29 people engaged in non-aerobic stretching exercises for the same periods.

3) ___: The aerobic group showed significant increases in brain volume compared to the non-aerobic group.

1) Prediction

2) Experiment

3) Results

A chemical compound that releases H+ to solution is an ___.

acid

A compound that accepts H+ and removes it from solution is a ___.

base

To describe the acidity of a solution, chemists use the ___.

pH scale

___ are substances that resist pH change.

Accept H+ ions when they are in excess

Donate H+ ions when they are depleted

Buffers