Reading and Understanding Graphics
Up to 60% of all GED Science Exam questions include graphics. By becoming familiar with different types of graphics and learning about their essential components, you will be better prepared to answer GED Science Exam questions that contain graphical information.
When looking at a chart or a graph, look at the title or caption first. This will give you an overview of what the graphic is showing. Next, look at any legends or axis labels provided. This will give you an idea of what variables are shown. Make a list of the variables. Once you have done that, you can try to interpret the chart or graph by noting any trends you may see. How is one variable changing in response to the other? Next, you can read the question and attempt to answer it. Here is more specific information about graphics.
Charts
All charts are composed of rows (horizontal) and columns (vertical). Entries in a single row of a chart usually have something in common, and so do entries in a single column. Determine what the common elements are when you try to answer the questions on the GED Science Exam.
Graphs
Three common types of graphs are scatter plots, bar graphs, and pie graphs. Here you will find a brief description of each.
Whenever a variable depends continuously on another variable, this dependence can be visually represented in a scatter plot. Examples include a change in a property (such as human population) as a function of time. A scatter plot consists of the horizontal (x) axis, the vertical (y) axis, and collected data points for variable y, measured at variable x. The variable points are often connected with a line or a curve. A graph often contains a legend, especially if there is more than one data set or more than one variable. A legend is a key for interpreting the graph.
Look at the sample graph. The essential elements of the graph—the x- and y-axes—are labeled. The legend to the right of the graph shows that dots are used to represent the variable points in data set 1, while squares are used to represent the variable points in data set 2. If only one data set exists, the use of a legend is not essential.
Bar graphs are similar to scatter plots. Both have a variable y plotted against a variable x. However, in bar graphs data is represented by bars, rather than by points connected with a line. Bar graphs are often used to indicate an amount or level, as opposed to a continuous change. Pie graphs are often used to show what percentage of a total is taken up by different components of that whole.
Diagrams
Diagrams could be used to show a sequence of events, a chemical or biological process, the setup of a science experiment, a phenomenon, the relationship between different events or beings, and so forth. When you see a diagram, first ask yourself what its purpose is. What is it trying to illustrate? Then look at the different labeled parts of the diagram. What is their function? How are they interrelated?
Reading and Understanding Scientific Passages
When you read a scientific passage, the most important thing is to focus on the big picture, or on what the passage is about. In many ways, the reading passages in the science part of the GED are the same as the reading passages in other areas. One important difference is that science passages may expose you to science jargon, specialized vocabulary you may not be familiar with. Try not to let new words throw you off. You may be able to guess their meaning from the context. Even if you can't, keep reading. The questions following the passage may not require you to understand that particular word.
Series of Questions Based on a Passage or Graphic
On the GED Science Exam, you will sometimes be asked more than one question based on the same graphic or passage. When this is the case, it is worth your while to invest a little more time to understand the graphic or passage. Even if you are unsure about the first one, try answering the rest of the questions—they may be easier for you.
Experiment Skills
Experiments should be designed and conducted in accordance with the principles of the scientific method. This means that the goal of the experiment should be carefully formulated and the experiment should be set up to yield factual results. Review the concepts of the scientific method in the Science as Inquiry chapter if the tips included in this section are unfamiliar to you.
Setting Up an Experiment
Experiments should be set up to test one clearly formulated and testable hypothesis. The number of variables (things changing) in the experiment should be limited and carefully controlled. If possible, experiments should contain a control group. For example, if you were to study the effect of a new soil supplement on house plants, the soil supplement should not be used on a few plants, which will comprise the control group. If there is improvement in the growth of only the plants on which the supplement was used, then there is strong indication that the supplement increases the plant growth. If, however, the plants in the control group grow as much as the plants on which the supplement was used, then the causes of growth most likely are not linked to the supplement. In this example, there would be two variables—1) the use of the supplement and 2) the plant growth.
How the supplement is administered and how plant growth is measured would need to be carefully described and controlled. For example, the scientist conducting the experiment would need to decide whether the supplement would be administered once, several times, or every day throughout the experiment. The scientist would also need to define what constitutes plant growth—the vertical increase, the number of new leaves, the growth of new branches and leaves, or some combination of these factors. One choice is not necessarily better than the others. Measuring the vertical growth wouldn't necessarily be worse than counting the number of new leaves. The important issue is to be consistent. If the number of leaves per plant is recorded on the first day, the number of leaves per plant should be recorded every day.
On the GED Science Exam, you may be asked to pick out the best design for an experiment. Before you look at the choices, determine what the important variables are, and think what would make a good control. Select the choice that contains the variables you thought of, that has the most logical experimental control, and in which the variables not studied are held constant.
Interpreting Others' Results
In some GED Science Exam questions, you will be asked to interpret others' results. You will need to make a generalization about the results or to draw a conclusion. Don't base your answer on what you believe is right. Base your answers on the results provided. Look at the choices given. Some could be inaccurate—if one part of the result doesn't fit the description in the choice, the choice is wrong (unless words such as generally or in most cases make room for exceptions). Make sure you don't jump to conclusions. A trend doesn't always indicate a cause and effect relationship. For example, every morning your alarm clock goes off and every morning you get hungry. However, the alarm clock is not what is making you hungry. The two events just happen to occur at the same time. Before you conclude that there is a cause and effect relationship, consider other conclusions, and then pick the most logical one.
Analyzing Experimental Flaws
A common GED Science Exam question requires you to analyze the flaws of an experiment. Experiments should be based on the scientific method. Common experimental flaws include:
- not testing the hypothesis
- having too many variables
- unforeseen variables
- lack of experimental control
- jumping to conclusions
Applying Scientific Conclusions
What good is science if we don't benefit from it? How would the finding that keeping a laptop on your lap for too long can damage your pelvic organs influence you? You would not keep the laptop on your lap for too long, right? Many questions on the GED Science Exam require you to apply a scientific conclusion, either to your personal life or to global phenomena. These are almost always questions from the problem-solving category. You are presented with a fact in one context and asked to apply it in another context. For example, if you read in a passage about different methods of determining the poles of the Earth in nature without a compass, you could be asked which of the methods would best work if you were in a particular situation—lost on a cloudy night in a forest, on the ocean on a clear day, etc. If necessary, as you are reading information provided in the question, make quick diagrams and summarize the important concepts on a piece of scrap paper. These strategies may help you visualize the concepts or the situation given and could help you make sense of the question.
Other Useful Skills
The more material you are exposed to, the easier it will become to understand it. Reading about science and applying science takes practice, just like riding a bike. At first you may be a bit clumsy with it, but if you stick with it, you improve rapidly and it begins to click. To comprehend science better, read as much about science as you can—in newspapers, magazines, and online. Make sure you look at graphics as well. As you are reading, think about what the passage or graphic is communicating to you. What are the possible applications of the science concepts discussed? What can you conclude based on the information given? What methods were used to arrive at the facts presented? Is anything that is presented an opinion or belief rather than a fact? Try to make up questions about the passage or graphic you read. Imagine that you are making up the GED Science Exam: What could you ask the students? By anticipating the move of your opponent, you are better prepared to respond to it.
Science Glossary
A good working science vocabulary is a very important asset when taking the GED Science Exam. Remember that the best way to learn vocabulary is also the easiest: make long lists of words you don't know and then break them down into short lists. Learn a short list every day.
You should also try and write sentences using the new scientific words.When you learn a new word, use it in conversation as soon as possible. Repetition is key—use a word three times, and it's yours!
Another alternative is to work with flash cards. Flash cards are pieces of paper or index cards that are used as a learning aid.Write the science word on one side and the definition on the other. Or, try writing a sentence that uses the word on one side of the flash card and the definition of the word on the other. Flash cards are easy to handle, they're portable, and they're friend-friendly, so you can study with a buddy. You and your friends can drill each other. If you can make games out of learning new science terms, studying will be more fun and you will learn more as well!
Now, review the following glossary.
acceleration: the rate that velocity changes per unit of time and the direction it changes in, computed from the change in velocity divided by the change in time. Common units are meters per second squared (
).
acceleration due to gravity: the acceleration of an object that is only acted on by the force of the Earth's gravity. This value is given the symbol g, and near the surface of the Earth it has a value of approximately 9.8 . The direction of acceleration due to gravity is downward.
accuracy: the closeness of an experimental measurement to the accepted or theoretical value
acid: a substance that is a proton donor. The pH of an acid is less than 7.
analysis: a stage in the scientific method where patterns of the observations are made
aqueous solution: a solution in which the solvent is water
arteries: the vascular tissues that carry blood away from the heart
astronomy: the study of the planets, stars, and space
atom: the smallest structure that has the properties of an element. Atoms contain positively charged protons and uncharged neutrons in the nucleus. Negatively charged electrons orbit around the nucleus.
ATP (Adenosine Triphosphate): a chemical that is considered to be the "fuel" or energy source for an organism atria: the chambers of the heart that receive blood base: a substance that is a proton acceptor. The pH of a base is greater than 7.
calibration: the examination of the performance of an instrument in an experiment whose outcomes are known, for the purpose of accounting for the inaccuracies inherent in the instrument in future experiments whose outcomes are not known
capillaries: vascular tissues that receive blood from the arterioles and release the blood to the venuoles
catalyst: an agent that changes the rate of a reaction, without itself being altered by the reaction
celestial equator: the extension of the Earth's equator out onto the celestial sphere
celestial poles: the extension of the Earth's north and south poles onto the celestial sphere
celestial sphere: the imaginary sphere which all the stars are viewed as being on for the purposes of locating them
cell membrane: an organelle found in all cells that acts as the passageway through which materials can pass in and out. This organelle is selectively permeable, only allowing materials to pass through that it "chooses" chemically.
cell wall: an organelle found primarily in plant cells and fungi cells, and also some bacteria. The cell wall is a strong structure that provides protection, support, and allows materials to pass in and out without being selectively permeable.
centripetal force: the net force that acts to result in the centripetal acceleration. It is not an individual force, but the sum of the forces in the radial direction. It is directed toward the center of the circular motion.
chemical change: a process that involves the formation or breaking of chemical bonds
chromosome: an organelle that contains the entire DNA of the organism
component: the part of a vector that lies in the horizontal or vertical direction
compound: a substance composed of more than one element that has a definite composition and distinct physical and chemical properties
concentration: a measure of the amount of solute that is present in a solution. A solution that contains very little solute is called dilute. A solution that contains a relatively large amount of solute is said to be concentrated.
conclusion: the last stage of the scientific method, where explanations are made about why the patterns identified in the analysis section occurred
constellation: an apparent grouping of stars in the sky that is used for identification purposes. These stars are not necessarily near each other in space, since they are not necessarily the same distance from the Earth.
continental rift: the region on a continent where new crust is being created, and the plates on either side of the rift are moving apart
convergent boundary: a boundary between two of the Earth's plates that are moving toward each other
cosmology: the study of the formation of the universe
crystal: a solid in which atoms or molecules have a regular repeated arrangement
current: the flow of charge past a point per unit time; current is measured in amperes (A)
cuticle: the top layer on a leaf. It is a nonliving layer consisting primarily of wax that is produced by the epithelium, a cell layer directly underneath.
cytoplasm: a jellylike substance located in the cell where all of the internal organelles can be found. The cytoplasm consists primarily of water and supports the cell and its organelles.
cytoskeleton: organelles that are the internal "bones" of the cell. They exist in thick and thin tubules.
decibel: a unit of measure for the relative intensity of sounds
declination: measures how many degrees, minutes, and seconds north or south of the celestial equator an object is
delta: a fan-shaped deposit of material at the mouth of a river
density: the mass of a substance for a given unit volume. A common unit of density is grams per milliliter (g/ml).
displacement: the change in position of an object, computed by calculating the final position minus the initial position. Common units of measure are meters (m).
divergent boundary: a boundary between two of the Earth's plates that are moving away from each other
DNA: contains all genetic material for an organism. The smallest units of DNA are called nucleotides.
ecliptic: the apparent path of the Sun across the sky over the course of a year
electric potential energy: the energy due to an object's position within an electric field
electromagnetic wave: a light wave that has an electric field component and a magnetic field component. An electromagnetic wave does not require a medium to travel through.
electrostatic force: the force that exists between particles due to their charge. Particles of like charge repel, particles of unlike charge attract.
element: the smallest entity that has distinct chemical properties. It cannot be decomposed by ordinary chemical reactions.
ellipse: a geometric shape that is formed when a plane intersects with a cone. In this case, the plane intersects the cone at an angle, so that a shape similar to a circle but stretched in one direction is formed. The orbits of the planets around the Sun represent ellipses.
endoplasmic reticulum: an organelle that is used to transport proteins throughout the cell
energy: the ability to do work or undergo change. Kinetic energy is the energy of motion, while potential energy is stored energy.
epicycle: smaller circles on which the planets traveled around the Earth in the geocentric model of the solar system. Epicycles were used to explain the retrograde motion of planets and helped make the predicted positions of the planets match the observed positions.
equilibrium: a state at which the forward and reverse reactions proceed at the same rate
focal length: the distance from a focal point to a mirror or lens
force: that which acts on an object to change its motion; a push or pull exerted on one object by another. Common units are newtons (N).
freefall: an object in one-dimensional motion that is only acted on by the force of the Earth's gravity. In this case, its acceleration will be –g or g downward.
frequency: the number of cycles or repetitions per second. Frequency is also often measured as the number of revolutions per second. The common units of frequency are hertz (Hz), where one hertz equals 1 cycle/second.
frictional force: the force that acts parallel to surfaces in contact opposite the direction of motion or tendency of motion
functional group: a group of atoms that give a molecule a certain characteristic or property
gel electrophoresis: a process used in laboratories to determine the genetic makeup of DNA strands. This process involves the movement of chromosomes through a gel from one pole to the other. Magnetism is used to pull the chromosomes through the gel.
geocentric model: the model of the solar system that places the Earth at the center with the planets and the Sun orbiting around it
geology: the study of rocks and minerals
glacier: a large mass of snow-covered ice
Golgi apparatus: an organelle that packages proteins so that they can be sent out of the cell
gravitational force: the attractive force that exists between all particles with mass
heliocentric model: the model of the solar system that places the Sun at the center with the planets orbiting around it
heterogeneous: a mixture that is not uniform in composition
homogeneous: a mixture in which the components are uniformly distributed
hydrate: a crystal of a molecule that also contains water in the crystal structure. If the water evaporates, the crystal becomes anhydrous.
hydrology: the study of the Earth's water and water systems
hypothesis: a step in the scientific method where a prediction is made about the end result of an experiment. A hypothesis is generally based on research of related data.
igneous rock: a rock formed through the cooling of magma
image distance: the distance from an image to a mirror or lens
inertia: the tendency of an object to follow Newton's First Law, the law of inertia. That is the tendency of an object to remain at rest or in motion with constant velocity unless acted on by a force.
inorganic: a material that is neither plant nor animal in origin
intensity: the power per unit area of a wave; measured in Watts/m2
ion: an atom that has either lost electrons to become a positively charged cation, or has gained electrons to become a negatively charged anion
isomers: substances that have the same molecular formula (same number of elements) in different arrangements
isotopes: atoms of the same element, with different numbers of neutrons, and hence a different atomic mass
Jovian planet: one of the outer planets of the solar system that have characteristics similar to that of Jupiter. They are also called gas planets. They are large, have high mass, have many moons, may have rings, are far from the Sun and each other, have thick atmospheres, are gaseous and have low density, have a composition similar to that of the Sun, have short rotation rates, and have long revolution periods around the Sun. The Jovian planets are Jupiter, Saturn, Uranus, and Neptune.
kinetic energy: the energy due to an object's motion or velocity
land breeze: the breeze that develops on the shoreline due to unequal heating of the air above the land and ocean. Land breeze occurs at night when the air above the land is cooler and the air above the ocean is warmer. The breeze blows from the land to the sea.
latitude: the coordinate used to measure positions on the Earth north or south of the Earth's equator. Latitude is measured in degrees, minutes, and seconds. Zero degrees latitude is the Earth's equator.
longitude: the coordinate used to measure positions on the Earth east or west of the prime meridian, which goes through Greenwich, England. Longitude is measured in degrees, minutes, and seconds.
longitudinal wave: a wave that has the direction of motion of the particles in the medium parallel to the direction of motion of the wave. Sound is an example of a longitudinal wave.
mass: the amount of matter in an object; also a measure of the amount of inertia of an object. Common units are kilograms (kg).
meander: a broad curve in a river
meiosis: a process of cellular reproduction where the daughter cells have half the amount of chromosomes. This is used for purposes of sexual reproduction to produce sex cells that will be able to form an offspring with a complete set of chromosomes with different DNA than the parents.
meniscus: the curved surface of a liquid in a container, caused by surface tension
metamorphic rock: a rock whose crystal structure has been changed through heat and/or pressure
meteorology: the study of the Earth's atmosphere and weather
mid-oceanic ridge: a region under the ocean where new crust is being created, and the plates on either side of the ridge are moving apart
mineral: a naturally occurring element or compound found in the Earth's crust
mitochondria: an organelle that produces ATP
mitosis: a process in which cells produce genetically identical offspring
mixture: a physical combination of different substances
mole: the amount of substance that contains as many particles as there are atoms in 12 grams of the carbon 12 isotope (6.022 × 1023 particles)
molecular mass: the sum of the atomic masses in a molecule
molecule: a substance formed by a chemical bond between two or more atoms
net force: the vector sum of all the forces acting on an object
newton: the metric and System International unit of force. One newton equals one kg/s2.
non-renewable resource: a resource that is not replaced in nature as quickly as it is used. In many cases it is not replaced or re-formed at all.
normal force: this force acts between any two surfaces in contact. It is the part of the contact force that acts normally or perpendicular to the surfaces in contact.
nucleolus: an organelle found inside a nucleus that is responsible for the production of ribosomes
nucleotide: the smallest unit of DNA. There are five different types of nucleotides: adenine, guanine, thymine, cytosine, and uracil. The arrangement of genes is based directly on the specific arrangement of nucleotides.
nucleus: an organelle in a cell that contains all of the DNA and controls the functions of the cell
object distance: the distance from an object to a mirror or lens
oceanography: the study of the Earth's oceans
orbit: the path an object takes as it travels around another in space
organic: a material that is plant or animal in origin
oxbow lake: a crescent-shaped lake formed when a meander is cut off from the river it was part of
oxidation: the loss of electrons by a substance in a chemical reaction
parallel circuit: a circuit with more than one path for the current to follow
period: the time, often measured in seconds, for one complete repetition or rotation
phloem: vascular tissue found in plants that transports mostly sugar and water; can travel either "shoot to root" or "root to shoot."
photon: a particle of light. A discreet amount of light energy where a single photon of light is the smallest unit of light energy possible.
photosynthesis: a process by which the sunlight's energy, water, and carbon dioxide are transformed into sugar and oxygen
physical property: a property that can be observed without performing a chemical transformation of that substance
plate tectonics: the theory in which Earth's crust is made up of many plates that float on the mantle. This theory explains the movement of the continents, the formation of mountains and volcanoes, and the existence of mid-oceanic ridges and earthquakes.
polymer: a large molecule made up of repeating units of one or more small molecules (monomers)
position: the location of an object in a coordinate system. Common units of measure are meters (m).
potential difference: the difference in electric potential energy per unit charge between two points. This is commonly called voltage. The common unit of measure for potential difference is called volts.
potential energy: the energy due to an object's position or state
precession: the process by which the Earth's axis traces out a circle on the celestial sphere
precision: the closeness of measurements obtained from two or more experimental runs
pressure: force per unit area.Units used to measure pressure are torr, atmosphere (atm), and pascal (pa).
procedure: a logical list of steps that explain the exact actions taken to perform an experiment
projectile: an object in two-dimensional motion that has a vertical acceleration equal to –g (or g downward) and a horizontal acceleration of zero
protein synthesis: a process by which DNA will transport its information by way of RNA to the ribosomes where proteins will be assembled
qualitative observation: an observation that includes characteristics other than amounts or measurements; may include shapes, colors, actions, and odors
quantitative observation: an observation that includes characteristics of measurements or amounts
radiation: the emission of energy
reactant: a substance that is consumed in a chemical reaction to form products
reduction: the gain of electrons by a substance in a chemical reaction
renewable resource: a renewable resource is replaced in nature as quickly as it is used
resistance: the resistance to the flow of electrons through a circuit. The resistance is dependant on the current flowing through the circuit element and the voltage across the circuit element; resistance is measured in ohms.
respiration: a process by which sugar is converted into ATP and carbon dioxide; may include oxygen, which is called aerobic respiration
retrograde motion: the apparent westward motion of objects in the sky from one night to another
reversible reaction: a reaction in which products can revert back into reactants
ribosome: an organelle where protein synthesis occurs; can be found floating freely in the cytoplasm or attached to the outside of endoplasmic reticulum
right ascension: the celestial coordinate similar to that of longitude on the Earth. Right ascension is measured in hours, minutes, and seconds with 24 hours making up 360° around the celestial sphere.
river system: a river and its associated tributaries and drainage basin
RNA: ribonucleic acid; responsible for transmitting genetic information from the DNA to the ribosomes for protein synthesis
rock cycle: the rock cycle summarizes how rocks of different types are formed and how they can be transformed from one type into another
scalar: a quantity that has a magnitude or amount only
scientific method: a process by which data is collected to answer an integral question. The major steps are problem, hypothesis, research, procedure, observations and data collection, analysis of data, and conclusion.
sedimentary rock: a rock made up of sediments that have been deposited and compacted and cemented over time
sea breeze: the breeze that develops on the shoreline due to unequal heating of the air above the land and ocean. Sea breeze occurs during the day when the air above the ocean is cooler and the air above the land is warmer. The breeze blows from the sea to the land.
series circuit: a circuit with only one path for the current to follow. The current in each element in a series circuit is the same.
solubility: the amount of solute that can be dissolved completely in a solvent at a given temperature
solution: a homogeneous mixture of a solute (usually solid, but sometimes liquid or gas) in a solvent (usually a liquid, but sometimes a solid or gas)
speed: the magnitude of velocity. It measures the rate position changes with time without regard to the direction of motion; common units are meters per second (m/s).
speed of light: The speed of light in a vacuum is the fastest speed possible. As light travels in other materials, it will change speed. The speed of light in any material is still the fastest speed possible in that material; commonly denoted by the symbol c.
spindle fiber: an organelle used during mitosis and meiosis that separates and "pulls" chromosomes toward the opposite poles of the cell
spontaneous reaction: a reaction that does not require an external source of energy to proceed
star: a body composed mostly of hydrogen and helium that radiates energy and that has fusion actively occurring in the core
states of matter: solid, liquid, and gas. In solids, atoms or molecules are held in place. The shape and volume of a solid usually do not vary much. In liquids atoms or molecules can move, but their motion is constrained by other molecules. Liquids assume the shape of their container. In gases the motion of atoms or molecules is unrestricted. Gases assume both the volume and the shape of their containers and they are easily compressible.
temperature: the measure of the average kinetic energy of the molecules of a substance
tension: the force that acts and is transferred along ropes, strings, and chains
terminal moraine: a ridge of material deposited by a glacier at its farthest point of advance
terrestrial planet: one of the inner planets of the solar system that have characteristics similar to that of the Earth. They are small, have low mass, have few or no moons, have no rings, are close to the Sun and are close to each other, have thin or no atmosphere, are rocky and have high density, have long rotation rates, and have short revolution periods around the Sun. The terrestrial planets are Mercury, Venus, Earth, and Mars.
topography: the study of the surface features of the planet primarily through mapping
transverse wave: a wave that has the direction of motion of the particles in the medium perpendicular to the direction of motion of the wave.
uniform circular motion: motion with constant speed in a circle. Since the direction of the velocity changes in this case, there is acceleration even though the speed is constant.
valence electrons: electrons that are in the outer atomic shell and can participate in a chemical reaction
vector: a quantity that has both a magnitude (an amount) and a direction. In one-dimensional motion, the direction can be represented by a positive or negative sign. In two-dimensional motion, the direction is represented as an angle in the coordinate system.
veins: in plants, found in the leaves; sometimes called the vascular bundle that contains the xylem and phloem. In animals, tubelike tissue that usually transports blood.
velocity: the rate that a position changes per unit time and the direction it changes in. Common units are meters per second (m/s).
ventricles: chambers found in animal hearts that pump blood away from the heart
voltage: another name for potential difference
voltmeter: a device used to measure voltage in a circuit
water cycle: the movement of water between the land, oceans, and atmosphere
weight: the force of the Earth's gravity on an object. Near the surface of the Earth the weight is equal to the object's mass times the acceleration due to gravity (W = mg).
xylem: vascular tissue found in plants that transports water in one direction: "root to shoot." This is the water that will be sent to the photosynthetic cells in order to perform photosynthesis.
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