GED Science

Question 1

Independent and dependent variables

Answer 1

IV is what is intentionally varied in the study.
DV is what is measured.

The phenomenon you are studying is called the DV.
A factor that you believe might be affecting that phenomenon is called the IV.

Question 2

Fact, law, theory

Answer 2

A fact is simply an observation.
A law is description, repeatedly observed to be true, of a phenomenon and how it occurs.
A theory is a well-tested and generally accepted explanation of why a phenomenon occurs.

Question 3

Scientific Method

Answer 3

Is a set of techniques that scientists use to investigate observable facts and occurrences and to acquire new knowledge. Steps:
1. Observe a phenomenon and formulate a question about it
2. Collect data
3. Form a hypothesis - an educated guess about the answer to your question
4. Test the hypothesis through an experiment - a fair test of the hypothesis. You may need to adjust the experiment by changing only one factor at a time while controlling other factors. You should also repeat the experiment to make sure the first results are valid.
5. Draw a conclusion

Question 4

Taking Samples

Answer 4

A sample is a portion of the entire thing or population. The sample must be representative (not different from the population in an important way). An unrepresentative sample introduces bias into the results.
One way to prevent bias is to select a large enough sample size to reduce the probability that, by random chance, the sample differs significantly from the population.
Furthermore, scientists use randomization to increase the chance of valid results.

Question 5

Observational Study

Answer 5

A type of study in which the scientist does not manipulate the conditions.

Question 6

Reasoning with Scientific Information

Answer 6

requires citing specific evidence to support a conclusion.

Question 7

Unicellular Organisms

Answer 7

Bacteria and protozoa

Question 8

Basic Life Functions

Answer 8

Movement, growth, cell maintenance, reproduction, and the manufacture of specialized substances

Question 9

Basic Cell Structures

Answer 9

All cells have a cell membrane, cytoplasm, and genetic material. Unlike an animal cell, a plant cell contains a cell wall that gives the cell rigidity and shape.

Question 10

Prokaryotes and eukaryotes

Answer 10

Bacteria are called prokaryotes. In bacteria, the genetic material consists of a single molecule suspended in the cytoplasm. In all other cells, the genetic material is contained within a nucleus. Such cells are called eukaryotic. All plant and animal cells are eukaryotic.

Question 11

Photosynthesis Reaction

Answer 11

6CO2 + 6H2O => C6H12O6 + 6O2
Carbon dioxide plus water, in the presence of light energy, yields glucose plus oxygen.

Question 12

Cellular Respiration

Answer 12

When energy is needed in a cell, carbohydrates are broken down to release energy in a process called CR:

Oxygen from the air reacts with glucose from food to yield carbon dioxide, water, and energy.

C6H12O6 + 6O2 => 6CO2 + 6H2O + energy

Photosynthesis and cellular respiration help keep the amounts of oxygen and carbon dioxide in the atmosphere fairly constant.

Question 13

Levels of Organization in the Human Body

Answer 13

There are four levels:
(1) cells - the smallest unit of life
(2) tissues - groups of similar cells that perform a specific function, such as muscle tissue
(3) organs - groups of tissues that perform a function, such as the stomach
(4) body systems - groups of organs working together to perform a function, such as digestion

Question 14

Human Body Systems

Answer 14

• Circulatory
• Respiratory
• Digestive
• Nervous
• Immune
• Endocrine
• Reproductive
• Urinary
• Skeletal
• Muscular

Question 15

Arteries and Veins

Answer 15

In arteries, blood flows away from the heart - so oxygenated blood towards the body’s cells and blood with carbon dioxide towards the lungs.

In veins, blood flows towards the heart - so blood with carbon dioxide from the body’s cells and oxygenated blood from the lungs.

Question 16

Infections

Answer 16

An infection is the invasion of the body by germs. The most common germs are bacteria and viruses, although infections can also be caused by fungi, protozoans, and worms.

Question 17

Habituation

Answer 17

Or psychological dependence, is a milder form of dependence than addiction - the urge to take the drug is strong, although there are no withdrawal symptoms.

Question 18

Asexual and Sexual Reproduction

Answer 18

In asexual reproduction, an offspring is identical to its parent. In sexual reproduction, an offspring is unique, inheriting traits from each parent. In humans, those specialized sex cells are called sperm and ova.

Question 19

Alleles

Answer 19

The factors that control inherited traits are called genes. Different forms of a gene are called alleles. A dominant allele hides a recessive allele.

Question 20

DNA

Answer 20

A DNA molecule is shaped like a spiral ladder. The sides of the ladder are made of deoxyribose - a sugar - and phosphate. Each rung of the ladder is made of a pair of nitrogen bases - adenine (A), guanine (G), thymine (T), and cytosine (C). A always pairs with T, and C always pairs with G.

Question 21

Homologous and Analogous Structures

Answer 21

Similar structures that organisms have inherited from a common ancestor are called HS.

AS have similar function (butterfly and bird wings, for example).

Question 22

Natural Selection

Answer 22

Several factors are involved in NS:
(1) Most species produce far more offspring than can survive
(2) These offspring compete with one another for scarce resources
(3) Members of a species have different traits, called variations. Some variations make individuals better adapted to survive
(4) Individuals with favorable variations are more likely to survive, reproduce, and pass the favorable traits to their offspring
(5) Over generations, helpful variations spread through a species, causing the species to change, or evolve.

Geographic isolation seems to play a big role in the evolution of new species. When a group of individuals remains separated from the rest of its species long enough, it may become a new species. This means that members of the new species will be unable to interbreed with members of the original species.

Question 23

Atoms

Answer 23

All matter is made of atoms. An atom is the smallest unit of matter that can combine chemically with other matter and that cannot be broken down into smaller particles by chemical means. Atoms are made of subatomic particles. The major ones are protons, neutrons, and electrons. Protons and neutrons form the nucleus of all atoms except hydrogen, which has just one proton in its nucleus. Electrons orbit the nucleus of an atom. When an atom has an equal number of protons and electrons, it is electrically neutral. When an atom gains or loses electrons, it becomes a negatively charged or positively charged ion.

The number of protons in the nucleus of an atom is called the atomic number.

Question 24

Matter Classification

Answer 24

Matter can be classified as elements, compounds, or mixtures.
- Elements are substances that cannot be broken down into other substances. They are made of a single type of atom.
- Compounds are substances formed of two or more elements chemically combined in a definite proportion. Compounds have properties that differ from the properties of the elements that they contain. Compounds are represented by chemical formulas (H2O).
- Mixtures are physical combinations of two or more substances that keep their own properties (salt water).

Question 25

Molecules and Bonds

Answer 25

When elements combine to form molecules or ionic compounds, their constituents are held together by bonds. There are two main types of bonds:
- Covalent - atoms share a pair of electrons, each atom contributing one electron (water)
- Ionic - atoms gain or lose electrons to become ions, and the attraction between positively and negatively charged ions holds the compound together (sodium chloride NaCl, i.e. table salt)

Question 26

Matter, Mass, Weight

Answer 26

Matter is anything that has mass and takes up space. The mass of an object is the amount of matter that it contains, and its weight is a measure of the gravitational force exerted on it. The mass of an object never changes, but its weight can change.

Question 27

States of Matter

Answer 27

Solids have a definite shape and volume because the molecules of which they are made occupy fixed positions and do not move freely. In some solids, such as minerals, the molecules form an orderly pattern called a crystal.

Liquids have a definite volume but no definite shape. A liquid conforms to the shape of its container.

Gases have no definite shape or volume.

The states of matter can be changed by adding or removing heat energy. The temperature at which a solid becomes a liquid is its melting point. The temperature at which a liquid becomes a gas is called its boiling point. The temperature at which a gas becomes a liquid is its condensation point. The temperature at which a liquid becomes a solid is its freezing point.

Water is the only substance that is found naturally in all three states on Earth.

Question 28

Solutions

Answer 28

A solution is a mixture (such as salt water) that is uniform throughout and that contains ions, atoms, or molecules of two or more substances. The substance in a solution that is dissolved is called the solute. The substance in which the solute is dissolved is the solvent. Water is called the universal solvent because so many substances dissolve in it.

Solutions are not always liquid. They can be solids, as when two or more metals are combined in an alloy, or they can be gases, as when oxygen and nitrogen are combined in the air.

Question 29

Chemical Reactions

Answer 29

The mass of the products always equals the mass of the reactants (the law of conservation of mass).

Chemical reactions are either endothermic (absorb energy) or exothermic (energy is given off with the products, usually in the form of heat or light).

Activation energy is the amount of energy needed to get a reaction going.

Question 30

Acids and Bases

Answer 30

An acid is a compound that releases hydrogen ions (H+), or protons, in the presence of water. Strong acids are corrosive.

A base is a compound that accepts hydrogen ions, or protons.

When an acid reacts with a base, the product is a salt and water. This reaction is called neutralization.

Question 31

Energy

Answer 31

Energy is the capacity to do work. Work is done whenever a force is applied to an object to set it in motion. Thus, anything that can force matter to move, change direction, or change speed has energy.

Energy comes in many forms:
- Heat
- Light
- Electrical
- Chemical
- Nuclear
- Mechanical
- Sound

Energy can be converted from one form to another.

The law of conservation of energy - energy can neither be created nor destroyed, only changed in form.

Two basic types of energy are potential and kinetic. Potential energy is the energy of position. Kinetic energy is the energy of motion.

Question 32

Work and Power

Answer 32

Work done is measured in joules. The rate of doing work or consuming energy is called power, and it is measured in horsepower (in the English system) or watts (joules per second in the metric system).

Question 33

Energy and Mass

Answer 33

E = mc2
E is energy
m is mass
c is the speed of light

Question 34

Speed, Velocity, Acceleration

Answer 34

Speed is the rate at which an object moves.
Velocity is speed in a given direction.
Acceleration is the rate at which velocity changes.

Question 35

Force

Answer 35

Is anything that changes the state of rest or motion of an object.

Question 36

The Laws of Motion

Answer 36

The first law of motion, the law of inertia - an object at rest will stay at rest until a force acts upon it, and an object in motion will stay in motion at a constant speed in a straight line until a force acts upon it.

The second law of motion, the law of motion or acceleration - the acceleration of an object depends on its mass and the force acting upon it. The greater the force, the greater the acceleration. The more massive the object, the more force it takes to accelerate it. If a constant force acts upon an object, the object will move with constant acceleration in the direction of the force.

The third law of motion - for every action, there is an equal and opposite reaction. This law was used to derive the law of conservation of momentum.

Momentum is related to the amount of energy that a moving object has, and it depends on the mass of the object and its velocity (object’s mass multiplied by its velocity). When an object is given a certain amount of momentum in a particular direction, some other object must receive an equal momentum in the opposite direction. All forces exist in pairs, all forces are interactions between objects.

Question 37

Static Electricity

Answer 37

Sometimes electrons are temporarily pulled away from atoms, creating stationary areas of positive and negative charge. This can happen when two objects, like a balloon and a rug, are rubbed together, creating static electricity.

Question 38

Electricity

Answer 38

The movement of charged particles through a substance, usually electrons, is an electric current. Direct current flows in one direction only and is used in battery-operated devices. Alternating current flows back and forth rapidly and is used in household wiring.

A material that allows electrons to move freely from atom to atom is called a conductor (metals). A material that does not allow electrons to move freely from atom to atom is called an insulator (rubber and plastic). Semiconductors are substances whose ability to conduct electricity is midway (silicon is used in electronic devices).

Question 39

Magnetism

Answer 39

An electric current produces a magnetic field that affects magnetic substances such as iron in the same way a permanent magnet does. Magnetic fields are produces by moving charged particles. In an electromagnet, the charged particles move along a coil of wire connected to a battery or other power source. In a permanent magnet, the spinning of electrons creates a magnetic field.

Question 40

Electric Current

Answer 40

Is a complete pathway for the flow of electric current. It consists of a source of electricity, such as a battery, wires along which the current travels, devices called resistors powered by the current, and often a switch to start and stop the flow of current.

To have current, you need to have a loop. Any break in the loop will stop current.

Question 41

Electric Motors, Generators, and Transformers

Answer 41

Just as an electric current produces a magnetic field, a moving magnetic field produces an electric current. This principle underlies electric motors, generators, and transformers.

In an electric motor, magnetic fields are produced by electric currents. The magnetic fields push against one another, turning the shaft of the motor.

In a generator, a moving magnetic field produces electric current.

In a transformer, an incoming electric current in coiled wire produces fluctuating magnetic fields, which in turn produce an outgoing electric current of a different voltage. The difference in voltage is caused by the differing sizes of the wire coils.

Question 42

Structure of Earth

Answer 42

Three main layers:
(1) the crust - consists of rocks, 5 to 64 km
(2) the mantle - consists of silica and metal-rich minerals, 2900 km
(3) the core - has two layers: the outer core (mostly liquid iron) and the inner core (mostly solid iron). Extreme heat and pressure characterize the core.

Question 43

The Theory of Plate Tectonics

Answer 43

Earth’s crust is made up of tectonic plates that fit together like a crude jigsaw puzzle. These plates move relative to one another at a rate of up to 15 cm (6 in) a year. At the boundaries between plates, major landforms such as mountain ranges, volcanoes, ocean trenches, and mid-ocean ridges form, and earthquakes occur.

Three types of plate boundaries, or margins:
(1) Constructive margin - two plates are moving apart and new crust is forming. Molten material from the mantle below wells up in the space between the plates, hardens, and forms new crust, usually at a mid-ocean ridge.
(2) Destructive margin - two plates colliding and crust is being destroyed. When a continental plate collides with an oceanic plate, the denser oceanic crust may be forced under the other plate, forming a deep trench. When two plates consisting of continental crust collide, the crust crumples to form mountain ranges.
(3) A transform, or conservative, margin - two plates are sliding by one another, and no crust is created or destroyed.

Question 44

Natural Resources

Answer 44

Include air, water, soil, minerals, and energy.

Less than 3% of the world’s water is fresh water.

Energy resources include fossil fuels, flowing water, wind, solar energy, and geothermal energy.

Question 45

Renewable Resources

Answer 45

Those whose supply will not run out, either because there is an unlimited supply (solar), or because the resource cycles through the environment (water). Renewal energy resources, in addition to solar, include the water power of flowing rivers, tidal and wave power from the movement of ocean water, wind power from the movement of air, and geothermal power from the heat in the Earth’s crust.

Question 46

Weather and Climate

Answer 46

Weather is the day-to-day change in conditions in the atmosphere at a particular place on Earth. Climate is the average weather conditions of a large region over a long period of time.

All weather and climate ultimately arise from the uneven heating of the Earth. The sun’s rays fall more directly at the equator than they do at the poles. This resulting uneven heating causes global wind circulation patterns: the warm air at the equator rises, creating an area of low pressure, and moves toward the poles. Cold air at the poles sinks, creating an area of high pressure, and moves toward the equator. This creates a pattern of prevailing winds in both hemispheres.

Another major influence on weather and climate is the worldwide pattern of ocean currents. Ocean currents are caused by the wind and by variations in the density of water (warm water is less dense than cold water). Ocean currents help transfer heat from the equatorial regions to the poles.

Question 47

Daily weather

Answer 47

Caused by the movement of air masses, large bodies of air with similar temperature, humidity, and pressure. The boundary between two air masses is called a front. A cold front occurs where a cold air mass overtakes and displaces a warm air mass. A warm front occurs where a warm air mass rises over a cold air mass. An occluded front occurs when a cold front catches up with a warm front and the two weather systems merge. Clouds and precipitation are characteristic of fronts.

Question 48

Layers of the Atmosphere

Answer 48

Troposphere - 0 to 6 miles
Stratosphere - 6 to 31 miles
Mesosphere and ionosphere - 31 to 50 miles
Thermosphere - 50 to 435 miles
Exosphere - 800 to 3000 km

Question 49

pH

Answer 49

Acidic and alkaine (or “basic”) are two extremes that describe substances, usually liquids or chemicals. A substance that is neither acidic nor alkaline is neutral.

The pH scale measures how acidic or alkaline a substance is. The scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic. Pure water is neutral, with a pH of 7.0. When chemicals are mixed with water, the mixture can become some level of either acidic or alkaline. Vinegar and lemon juice are acidic substances, while laundry detergents and ammonia are alkaline.

Question 50

Enzymes in chemical reactions

Answer 50

Are responsible for the conversion of one molecule into another, but they are not changed or used up.

Question 51

Newton’s Second Law

Answer 51

Fnet = m x a
Fnet is force
m is mass
a is acceleration

Question 52

Momentum Formula

Answer 52

p = m x v
p is momentum
m is mass
v is velocity