GED — All Questions

A line is parallel to y = 5x + 1. Its slope must be—

• a.5✓
• b.1
• c.−1/5
• d.−5

Parallel lines never meet, which requires identical slopes, so the slope is 5. The 1 is the intercept of the given line, not its slope. The value −5 describes a line falling as steeply as this one rises. And −1/5 is the slope of a line perpendicular to it.

Which equation describes a line with slope 3 that passes through (0, −4)?

• a.y = −4x + 3
• b.y = 4x − 3
• c.y = 3x + 4
• d.y = 3x − 4✓

Because the point given has x = 0, it is the y-intercept, so the equation is y = 3x − 4. Writing +4 puts the crossing above the origin instead of below. The equation y = −4x + 3 swaps the slope and the intercept. And y = 4x − 3 swaps them and changes the signs.

A scatterplot shows points rising from lower left to upper right. The two variables show—

• a.no association at all
• b.a negative association
• c.a perfect causal link
• d.a positive association✓

Points that rise together mean that as one variable increases so does the other, which is a positive association. A negative association would show points falling to the right. No association would show a shapeless cloud. And no scatterplot by itself establishes that one variable causes the other.

A repair shop charges $25 plus $5 for each hour of labor, so the cost is C = 25 + 5h. In this model the 5 represents—

• a.the total cost of a short job
• b.the fixed charge for any visit
• c.the cost of each additional hour✓
• d.the number of hours worked

The 5 multiplies the hours, so it is the rate at which cost grows with each hour, the slope of the line. The fixed charge that applies before any labor is the 25. A short job costs 25 plus whatever labor it takes, which is not 5 by itself. And the number of hours is h, the variable the 5 is multiplied by.

The graph of the equation y = x² is—

• a.a pair of parallel lines
• b.a U-shaped curve✓
• c.a straight line
• d.a circle

Squaring makes negative and positive x-values give the same positive y, so the graph is a parabola opening upward, symmetric about the y-axis. A straight line comes from an equation where x appears to the first power only. A circle requires both variables squared and summed. And parallel lines come from a pair of separate linear equations.

Which cell structure releases the energy stored in food molecules?

• a.The cell membrane
• b.The vacuole
• c.The mitochondrion✓
• d.The ribosome

Mitochondria carry out cellular respiration, breaking down sugars in the presence of oxygen and capturing the released energy in a form the cell can spend. The cell membrane controls what crosses into and out of the cell. A vacuole is a storage compartment, largest in plant cells. And ribosomes assemble proteins, a job that consumes energy rather than supplying it.

The instructions a cell uses to build its proteins are carried by—

• a.glucose
• b.DNA✓
• c.cholesterol
• d.hemoglobin

DNA stores the sequence information that specifies each protein, which is why it is copied before a cell divides and passed to both daughter cells. Glucose is a fuel molecule and carries no information. Hemoglobin is itself a protein, one of the products rather than the instructions. And cholesterol is a lipid that helps form membranes.

How do the cells produced by meiosis differ from those produced by mitosis?

• a.They contain no genetic material at all
• b.They carry twice the number of chromosomes
• c.They are unable to divide ever again
• d.They carry half the number of chromosomes✓

Meiosis halves the chromosome number to make sex cells, so that fertilization restores the full set rather than doubling it each generation. Doubling is exactly what meiosis prevents. The cells are not dead ends, since a fertilized egg divides many times. And they certainly contain genetic material; half a set is still a set.

An allele is described as dominant when it—

• a.shows in the trait even with one copy present✓
• b.appears only when two copies are present
• c.is found more often in a population
• d.changes into a different allele over time

A dominant allele expresses itself in the observable trait whenever it is present, so a single copy is enough to mask a recessive partner. Needing two copies is the definition of recessive, which is the contrast being drawn. Dominance says nothing about how common an allele is; rare alleles can be dominant. And alleles do not convert into one another, though mutation can create new ones.

Two parents are each heterozygous for a trait, carrying one dominant and one recessive allele. What fraction of their offspring is expected to show the recessive trait?

• a.One in four✓
• b.One in two
• c.None at all
• d.Three in four

A Punnett square for this cross gives one homozygous dominant, two heterozygous and one homozygous recessive, so a quarter of the offspring are expected to show the recessive form. One in two would be the result of crossing a heterozygote with a homozygous recessive parent. Three in four is the fraction expected to show the dominant trait. And a recessive trait can certainly appear, since both parents carry the allele without showing it.

The difference between an organism's genotype and its phenotype is that the phenotype is—

• a.the trait that can actually be observed✓
• b.the number of chromosomes in its cells
• c.the species to which it belongs
• d.the set of alleles it happens to carry

Phenotype names what shows: the height, the color, the enzyme activity you can measure. The alleles themselves are the genotype, the underlying combination that the phenotype partly reflects. Chromosome number is a feature of the karyotype rather than either term. And species membership is a classification, not an individual's expressed trait.

Natural selection acts on a population when—

• a.the environment stays exactly the same across generations
• b.organisms decide which traits to pass on
• c.every individual remakes itself to suit the habitat it lives in
• d.individuals with certain traits leave more offspring✓

Selection works through differential reproduction: heritable traits that help their bearers survive and breed become more common in later generations. Individuals do not remake themselves to fit their surroundings; the variation is already present and is sorted. A wholly unchanging environment gives selection less to act on rather than more. And no organism chooses what it transmits.

The similar bone arrangement in a human arm, a whale flipper and a bat wing is evidence that these animals—

• a.use their limbs for the same task
• b.share a common ancestor✓
• c.belong to the same living species
• d.live in the same kind of habitat

The same underlying skeletal plan put to very different uses is what biologists call a homologous structure, and shared ancestry is the explanation for the shared plan. The three animals live in quite different habitats, which is part of the point. Their limbs do entirely different jobs, so function cannot explain the resemblance. And they are unmistakably separate species.

A bacterial population survives repeated treatment with the same antibiotic and becomes harder to kill. This is best explained as—

• a.the antibiotic itself growing weaker with repeated use
• b.selection of resistant individuals already present✓
• c.bacteria gradually learning how to avoid the medicine
• d.patients becoming immune to the drug

Chance variation means a few bacteria can survive the drug, and when the rest are killed those few multiply, so resistance spreads through the population. Bacteria have no capacity to learn anything. The chemical itself does not weaken; the population changes. And it is the bacteria, not the patient, that become resistant, which is why the distinction matters clinically.

The role of an enzyme in a cell is to—

• a.carry oxygen in the blood
• b.speed up a chemical reaction✓
• c.store genetic information
• d.form the wall of the cell

Enzymes are catalysts: they lower the energy needed for a specific reaction so it proceeds fast enough to sustain life, and they emerge unchanged to do it again. Genetic information is stored in DNA. Oxygen transport is the work of hemoglobin. And cell walls are built from carbohydrates such as cellulose in plants.

Sweating when body temperature rises is an example of—

• a.metabolism
• b.photosynthesis
• c.homeostasis✓
• d.reproduction

Homeostasis is the maintenance of steady internal conditions, and evaporating water off the skin is one of the body's ways of pushing temperature back toward its set point. Metabolism is the sum of chemical reactions in the body, which generates the heat rather than regulating it. Reproduction produces new organisms. And photosynthesis occurs in plants and some microbes, not in people.

In the human lungs, oxygen passes into the blood across the walls of—

• a.the diaphragm
• b.the alveoli✓
• c.the trachea
• d.the bronchi

The alveoli are the tiny sacs at the ends of the airways, thin-walled and richly supplied with capillaries, and gas exchange happens there. The trachea and the bronchi are conducting tubes that carry air toward them without exchanging much of anything. And the diaphragm is the muscle whose contraction draws air in.

Most absorption of nutrients from digested food takes place in—

• a.the large intestine
• b.the esophagus
• c.the small intestine✓
• d.the stomach

The small intestine is lined with folds and tiny projections that give it an enormous surface area, and it is where the products of digestion cross into the blood. The stomach mainly stores food and begins protein digestion with acid and enzymes. The esophagus only transports food downward. And the large intestine chiefly reclaims water and salts from what is left.

Signals travel through the human nervous system along—

• a.tendons
• b.alveoli
• c.neurons✓
• d.platelets

A neuron is the cell built for the job, receiving a signal at one end and passing it along its fiber to the next cell. Tendons are connective tissue joining muscle to bone. Platelets are blood cell fragments involved in clotting. And alveoli are air sacs in the lungs.

A vaccine protects against a disease by—

• a.prompting the immune system to prepare defenses✓
• b.blocking the germ from entering the body
• c.killing the germ once the first symptoms have appeared
• d.replacing the gene that causes the illness in a patient

A vaccine presents the immune system with a harmless version or piece of a pathogen so that antibodies and memory cells are ready before a real exposure. Killing germs after symptoms begin is what a treatment such as an antibiotic attempts. Gene replacement is gene therapy, a different technology for different diseases. And a vaccine does not form a barrier; the germ can still enter and is then met by a prepared defense.

Why are antibiotics ineffective against a viral illness such as influenza?

• a.Antibiotics act on features that viruses lack✓
• b.Antibiotics only work on animal cells
• c.Viruses are too small for any medicine
• d.Viruses reproduce faster than any drug acts

Antibiotics attack structures and processes specific to bacteria, such as the bacterial cell wall or bacterial ribosomes, and a virus has neither, which is why the drug has nothing to act on. Size is not the obstacle; antiviral medicines do exist. Antibiotics are not aimed at animal cells at all, which is what makes them safe to take. And speed of reproduction is not the reason the drug fails.

In photosynthesis, a plant uses carbon dioxide, water and light energy to produce—

• a.sugar and oxygen✓
• b.starch and hydrogen
• c.protein and nitrogen
• d.carbon dioxide and water

Photosynthesis builds a sugar from carbon dioxide and water and releases oxygen as a by-product, which is the source of nearly all the oxygen in the air. Protein synthesis requires nitrogen taken up separately as nitrate and is a different process. Plants do store starch, but it is made later from sugar, and hydrogen gas is not released. And carbon dioxide and water are the inputs, not the products.

Cellular respiration in human cells consumes glucose and oxygen and releases—

• a.sugar, oxygen and stored light energy
• b.nitrogen, water and heat only
• c.protein, salt and electrical charge
• d.carbon dioxide, water and usable energy✓

Respiration is the reverse direction from photosynthesis: the carbon in glucose leaves as carbon dioxide, the hydrogen ends up in water, and the energy released is captured for the cell's work with some lost as heat. Producing sugar and oxygen is what photosynthesis does. Protein and salt are not products of this reaction. And nitrogen plays no part in it.

In an energy pyramid for an ecosystem, the amount of energy available at each higher level—

• a.stays about the same
• b.doubles at every step
• c.decreases sharply✓
• d.increases sharply

Most of the energy an organism takes in is spent staying alive and lost as heat, so only a small fraction passes to whatever eats it, which is why food chains are short and top predators are few. Energy cannot increase as it moves up, since nothing is added. Staying constant would violate that same loss. And doubling is the opposite of what happens.

Decomposers such as fungi and bacteria are important to an ecosystem because they—

• a.control the size of predator groups
• b.add oxygen to the atmosphere
• c.return nutrients to the soil✓
• d.produce food from sunlight

Decomposers break down dead tissue and waste, releasing nitrogen, phosphorus and other elements in forms that plants can take up again, which is what keeps the nutrient cycle turning. Making food from sunlight is the producers' role. Predator numbers are regulated by prey supply and competition. And oxygen is added by photosynthesis, while decomposition generally consumes it.

The carrying capacity of a habitat is—

• a.the total area the habitat covers
• b.the number of different species it currently holds
• c.the rate at which its population grows each year
• d.the largest population it can support over time✓

Carrying capacity is set by the limiting resources — food, water, space, nesting sites — and a population that overshoots it falls back. The number of species present is richness, a measure of variety rather than of a ceiling. Growth rate describes how fast a population changes, not where it levels off. And area alone says nothing about how much life the ground can support.

A graph shows a rabbit population falling steeply one year. What is the most likely effect on the fox population that preys on those rabbits?

• a.It falls in the following period✓
• b.It rises immediately and then levels
• c.It is unaffected by the change
• d.It rises in the following period

Predators depend on their prey for food, so fewer rabbits means fewer foxes surviving and breeding, and the fox decline lags the rabbit decline by a season or more. A rise would require more food, not less. Being unaffected would mean the foxes had another equally good food source, which the question does not offer. And an immediate rise gets the direction and the timing both wrong.

An introduced species often spreads rapidly in its new range because—

• a.it reproduces more slowly than natives
• b.the new habitat has no resources for natives
• c.it needs fewer nutrients than any native
• d.local predators and diseases do not control it✓

A species arriving without the predators, parasites and diseases that held it in check at home can multiply faster than native competitors, which is what makes some introductions invasive. Slow reproduction would hinder the spread rather than help it. Lower nutrient needs may sometimes help but is not the general reason. And the habitat plainly does have resources, which is why natives were living there.

A bee gathers nectar from a flower and carries pollen to the next blossom. This relationship is—

• a.parasitism, because the bee harms the plant
• b.competition, because both want the same food
• c.mutualism, because both species benefit✓
• d.predation, because the bee consumes the plant

Each partner gains: the bee gets food and the plant gets its pollen delivered, which is the defining feature of mutualism. Parasitism would require the bee to live at the flower's expense, and pollination does the opposite. The two are not competing, since they are not after the same resource. And the bee does not kill or consume the plant, so this is not predation.

A food web is a better model than a single food chain because it shows—

• a.the seasonal migration of animals
• b.the exact number of each species
• c.the many feeding links in a community✓
• d.how long each organism lives

Most animals eat several things and are eaten by several others, so a web captures the branching connections that a single line cannot. Lifespan is not part of either model. Population sizes are shown in other diagrams, such as a pyramid of numbers. And migration is a behavior that neither a chain nor a web is built to display.

A person whose food supplies more energy than the body uses over a long period will most likely—

• a.lose weight through faster digestion
• b.store the excess as body fat✓
• c.convert the excess into vitamins
• d.excrete all of the excess energy

Energy that is taken in and not spent is stored, mostly as fat, which is the physical meaning of a sustained surplus. The body does not simply discard surplus energy; that is the whole reason a surplus matters. Vitamins are nutrients obtained from food and cannot be manufactured out of excess calories. And digestion does not speed up enough to make a surplus disappear.

Protein in the diet is used mainly to—

• a.carry oxygen to the lungs
• b.insulate the body against cold
• c.supply the fastest source of energy
• d.build and repair body tissue✓

Dietary protein is broken into amino acids that the body reassembles into its own proteins, from muscle fiber to enzymes, which is why needs rise during growth and healing. Oxygen is carried from the lungs by hemoglobin, not to them by protein in food. Insulation is largely the work of fat. And the quickest energy comes from carbohydrate.

Red blood cells are specialized to—

• a.produce digestive enzymes
• b.fight off invading bacteria and viruses
• c.help the blood form clots after an injury
• d.carry oxygen to the body's tissues✓

A red blood cell is packed with hemoglobin, which binds oxygen in the lungs and releases it where oxygen is scarce, and it even gives up its nucleus to make room. Fighting bacteria is the work of white blood cells. Clotting depends on platelets and plasma proteins. And digestive enzymes come from the pancreas and the gut lining.

The cell membrane contributes to the life of a cell by—

• a.copying the cell's genetic material
• b.controlling which substances enter and leave✓
• c.assembling amino acids into proteins
• d.converting sunlight into chemical energy

The membrane is selectively permeable, admitting some molecules, pumping others out and excluding the rest, which is how a cell keeps its interior different from its surroundings. Copying DNA happens in the nucleus. Capturing sunlight is the chloroplast's job in plants. And protein assembly takes place at the ribosomes.

A book rests on a table and stays there. Which statement best explains why, according to Newton's first law?

• a.No net force is acting on it✓
• b.Its mass has become zero
• c.The table exerts no force at all
• d.Gravity has stopped pulling on it

An object at rest stays at rest unless a net force acts, and here gravity pulling down is exactly balanced by the table pushing up, so the forces sum to zero. Gravity has not stopped; it is being opposed. The table is certainly pushing, and that push is half the balance. And the book's mass is unchanged, which is why gravity still acts on it.

A swimmer pushes backward against the water and moves forward. This illustrates Newton's third law because—

• a.the swimmer's mass increases in water
• b.the water pushes forward with equal force✓
• c.force and motion are unrelated in fluids
• d.water offers no resistance to motion

Forces come in pairs: the swimmer's push on the water is matched by the water's push on the swimmer, equal in size and opposite in direction, and that second force is what drives her forward. Water plainly does resist motion, which is why swimming is work. Mass does not change in water, though buoyancy changes apparent weight. And force and motion are tightly related here, as the third law says.

A net force of 20 newtons acts on a 4-kilogram cart. What is the cart's acceleration?

• a.24 m/s²
• b.0.2 m/s²
• c.5 m/s²✓
• d.80 m/s²

Newton's second law gives acceleration as force divided by mass, so 20 N ÷ 4 kg = 5 m/s². Multiplying instead of dividing gives 80 and reverses the relationship. Adding the two numbers gives 24, which mixes incompatible units. And dividing the mass by the force gives 0.2, the reciprocal of the right calculation.

Velocity differs from speed because velocity also states—

• a.the distance that was covered
• b.the direction of the motion✓
• c.the time the trip required
• d.the mass of the moving object

Speed is how fast something moves; velocity is how fast and which way, which is why two cars at the same speed in opposite directions have different velocities. Distance and time are the inputs that give speed in the first place. And mass appears in momentum and in force but not in either speed or velocity.

Acceleration is defined as the rate at which—

• a.force is applied
• b.mass is gained
• c.distance increases
• d.velocity changes✓

Acceleration measures how quickly velocity changes, which means an object speeding up, slowing down or merely turning is accelerating. Distance increasing over time is speed, one step back from acceleration. Force is what causes the acceleration rather than the quantity being measured. And mass is not changing in these problems at all.

A worker pushes a crate 3 meters along the floor with a steady force of 10 newtons in the direction of motion. How much work is done?

• a.3.3 joules
• b.13 joules
• c.300 joules
• d.30 joules✓

Work is force times the distance moved in the direction of the force, so 10 N × 3 m = 30 J. Adding the numbers gives 13 and ignores what work means. Dividing gives 3.3 and inverts the relationship. And 300 would require ten times the distance or the force.

A book sitting on a high shelf has energy because of its position. This energy is—

• a.thermal energy
• b.chemical energy stored in molecular bonds
• c.gravitational potential energy✓
• d.the kinetic energy of a moving body

Energy stored by virtue of position in a gravitational field is potential energy, and it converts to motion if the book falls. Kinetic energy belongs to objects that are actually moving, and this one is not. Chemical energy is stored in the bonds of molecules, as in fuel or food. And thermal energy is the energy of random particle motion, measured as temperature.

A swinging pendulum slows and finally stops. The law of conservation of energy says that its energy—

• a.was never present in the system
• b.turned into additional mass
• c.was destroyed by the friction
• d.changed into heat and sound✓

Energy is not lost but transferred, and friction at the pivot and drag through the air move it into heat and a little sound in the surroundings. Saying friction destroyed it contradicts the law being asked about. The pendulum plainly had energy while it swung. And converting to mass is a relativistic effect utterly negligible here.

In a sealed container, 10 grams of one substance react completely with 4 grams of another. What is the total mass of the products?

• a.6 grams
• b.10 grams
• c.14 grams✓
• d.It cannot be determined

Mass is conserved in a chemical reaction, so the products of a sealed reaction weigh what the reactants weighed: 14 grams. Subtracting gives 6 and treats the reaction as a loss. Reporting 10 keeps only the larger reactant. And the answer is entirely determinable, which is the point of the conservation law.

In the equation 2H2 + O2 -> 2H2O, the coefficient 2 in front of H2O tells you—

• a.how fast the reaction will proceed
• b.how many atoms are in one molecule
• c.how much heat the reaction gives off
• d.how many molecules of water are formed✓

A coefficient counts whole units of the substance, so two water molecules are produced for every oxygen molecule consumed. Atoms within a single molecule are counted by the subscripts, not the coefficient. Heat released is written separately as an energy term or measured in the laboratory. And the rate of reaction depends on conditions the equation does not record.

In an atom, the protons and neutrons are found—

• a.bonded to neighboring atoms
• b.orbiting outside the electron cloud
• c.spread evenly through the whole atom
• d.packed together in the nucleus✓

Almost all of an atom's mass sits in a tiny central nucleus made of protons and neutrons, with electrons occupying the far larger volume around it. An even spread through the atom was an early model that scattering experiments ruled out. Nothing orbits outside the electrons; they are the outermost part. And bonding involves electrons, not the nucleus.

The atomic number of an element equals the number of—

• a.bonds the atom can form
• b.particles in the nucleus
• c.protons in the nucleus✓
• d.neutrons in the nucleus

Atomic number counts protons, and it is what identifies the element: change it and you have a different element. Neutron number varies among isotopes of the same element, so it cannot be the identifier. Protons plus neutrons together give the mass number instead. And bonding capacity follows from the electron arrangement.

Two atoms are isotopes of the same element. They have—

• a.the same neutrons but different protons
• b.no neutrons in either nucleus
• c.different numbers of both particles
• d.the same protons but different neutrons✓

Isotopes share the proton count that defines the element and differ in neutrons, which makes them differ in mass while behaving almost identically in chemical reactions. Differing in protons would make them different elements altogether. Differing in both would likewise change the element. And only the lightest hydrogen isotope has no neutron, which is a special case rather than the definition.

An atom becomes an ion when it—

• a.joins with an identical atom
• b.is heated above its boiling point
• c.gains or loses one or more electrons✓
• d.gains or loses one or more protons

An ion is a charged atom, and charge appears when the number of electrons no longer balances the number of protons. Changing the proton count would change the element, which is a nuclear event rather than ionization. Heating can eventually strip electrons, but boiling alone does not make ions. And two identical atoms joining form a molecule, which is neutral.

Elements in the same column of the periodic table tend to—

• a.contain the same number of protons
• b.have the same atomic mass
• c.react in similar ways✓
• d.exist only as gases

A column, or group, collects elements with the same number of outer electrons, and since bonding is done by those electrons the group members behave alike chemically. Atomic mass rises steadily down a column rather than repeating. Only one group is entirely gaseous, so that cannot be a general rule. And identical proton counts would make them the same element.

A solution with a pH of 3 is—

• a.basic
• b.neutral
• c.saturated
• d.acidic✓

The pH scale runs from strongly acidic to strongly basic with 7 as neutral, so a reading of 3 lies well on the acidic side. Basic solutions read above 7. Neutral is 7 exactly, as pure water is at room temperature. And saturation describes how much solute a solution holds, which pH does not measure.