Science Diagnostic Test

Where the answer comes from: the table lists Mercury (0.39 AU) at 167 °C and Venus (0.72 AU) at 464 °C. The notes say "Venus has a very thick atmosphere made mostly of carbon dioxide, a gas that traps heat" and "Mercury has almost no atmosphere."

Step by step:

1. In order of distance, temperatures are 167, 464, 15, −65, −110, −140, −195, −200.
2. Every value falls except one: Venus (464 °C) is hotter than Mercury (167 °C), even though Venus is farther from the Sun.
3. The notes give the reason: Venus's thick carbon dioxide atmosphere traps heat (a strong greenhouse effect), and Mercury has almost no atmosphere to hold heat in.

The answer is Venus, because its thick carbon dioxide atmosphere traps heat.

Tip: To find what breaks a pattern, list the data in order and look for the one value that goes the wrong way. Then look in the passage for an explanation.

Evidence: body temperature was 37.0 °C at rest, rose only to 37.4 °C at minute 15 while jogging, and was back to 37.0 °C at minute 25. The passage adds that the volunteer "began sweating at about minute 10."

Step by step:

1. Range of body temperature: 37.4 - 37.0 = 0.4 °C. That is a very small change.
2. Over the same time, heart rate changed by 80 beats/min, so the body let heart rate change a lot but held temperature nearly steady.
3. Keeping internal conditions within a narrow range is homeostasis. Sweating, which began at minute 10, cools the skin as sweat evaporates.
4. Check the distractors: C says no effect (wrong, it rose 0.4 °C); D says it kept rising after jogging (it fell to 37.1); A compares it to heart rate (heart rate changed far more).

The answer is B.

Tip: words like no effect and always are risky. A small change is still a change, so check the actual numbers.

Evidence: the passage says the container was there "to absorb heat, so the water in the tube stayed at 22 °C for every trial."

Step by step:

1. The independent variable is light (lamp distance). The dependent variable is bubbles per minute.
2. A close lamp would also warm the water, and temperature affects photosynthesis too. Then you could not tell whether light or heat caused the change.
3. The water container keeps temperature the same, making it a controlled variable, so only light changes.
4. Eliminate A (the plant is already underwater), B (the container does not add light; it only blocks heat), and D (baking soda supplies CO₂).

The answer is C.

Tip: a good experiment changes only one thing at a time. When a setup step seems odd, ask which other variable it is keeping constant.

Where the answer comes from: the passage says the population already "includes both light-brown and dark-brown individuals," that "shell color is inherited," and that birds "hunt by sight." After dark ash covered the ground, the graph shows dark beetles rising from 10% to 85% over 20 generations.

Step by step (the parts of natural selection):

1. Variation: both colors existed before the eruption.
2. Inheritance: color is passed from parents to offspring.
3. Selection: on dark ash, light beetles stand out, so birds eat more of them. Dark beetles are more likely to survive and reproduce.
4. Time: over many generations, the dark-color trait becomes more common in the population.

Answer: On the dark ash, dark beetles were harder for birds to see, so more of them survived and reproduced, passing dark color to their offspring.

Why the others fail: individual beetles cannot change their inherited shell color because they need to (A). The passage says dark beetles existed before the ash, so the ash did not create them (C). Choice D reverses the predator effect: if birds preferred dark beetles, the dark share would fall.

Tip: natural selection acts on variation that already exists. Populations change over generations; individuals do not evolve during their lifetimes.

Evidence: The passage says "The density of water is 1.0 g/cm³. An object that is less dense than water floats in it." The Part 1 table gives each object's mass and volume.

Step by step:

1. Wood block: 30 \div 50 = 0.6 g/cm³ (less than 1.0 → floats).
2. Candle wax: 18 \div 20 = 0.9 g/cm³ (less than 1.0 → floats).
3. Rubber stopper: 33 \div 30 = 1.1 g/cm³ (more than 1.0 → sinks).
4. Glass marble: 15 \div 6 = 2.5 g/cm³ (more than 1.0 → sinks).

Only the wood block and the candle wax will float.

Tip: Floating depends on density (mass per volume), not on mass alone. The marble has the smallest mass but the greatest density, so it sinks.

Describe both the direction and the shape of the data.

Step by step:

1. Direction: as temperature rises from 55 °F to 80 °F, chirps rise from 15 to 40. The trend is upward (eliminates B).
2. Shape: each 5 °F step adds exactly 5 chirps (15 → 20 → 25 → 30 → 35 → 40). Equal steps make a straight line, a steady (linear) increase. It does not level off (eliminates C).
3. Choice D adds a cause-and-effect claim the graph cannot show. The data are about air temperature, and nothing in the study made crickets chirp on purpose.

The correct answer is A.

Tip: Equal changes in y for equal changes in x = a straight line (linear). Changes that grow larger = curving up; changes that shrink = leveling off.

Check each statement against the table. Only one needs information that is not there.

Step by step:

1. A: Brand A's mean is 23 mL, the lowest. Supported.
2. B: Brand B's mean (30) minus Brand A's mean (23) = 7 mL. Supported.
3. C: Each brand's trials are close together: A 22–24, B 29–31, C 34–36, all within 2 mL. Supported.
4. D: "Best value for the money" requires prices and possibly other qualities, and the test measured neither. Not supported.

The correct answer is D.

Tip: On "NOT supported" questions, the right answer usually brings in a new idea (price, strength, safety, taste) that was never measured. Supported statements can be checked with numbers you can point to.

Where the answer comes from: the passage says Year 1 had "28 inches of rain" and Year 2 "was a drought, with only 9 inches of rain." Soil moisture "was 31% in Year 1 and 9% in Year 2." It also says "the same brand and amount of fertilizer was used both years."

Step by step:

1. The fertilizer, corn variety, number of plots and planting date stayed the same. The big difference between the years was water.
2. Plants need both water and nutrients. If water is in short supply, adding more nutrients cannot make the plants grow much more, because water is now the limiting factor.
3. This one idea explains both results: with plenty of water (Year 1), nutrients were what held the corn back, so fertilizer helped. With little water (Year 2), extra nutrients barely helped.

Correct answer: C. Choice A has no support: the passage says the fertilizer was the same. Choice B contradicts the data, since fertilized plots still did slightly better in the drought. Choice D throws away a finding instead of explaining it.

Tip: A good reconciling explanation keeps all the findings true and points to a real difference in conditions between the studies.

Where the answer comes from: the passage says the data are "the average temperature for each month in the city of Lakeview," and the table's units are °F.

Step by step:

1. A scientific graph title should name the variable measured, the subject or place, and ideally the units or time span.
2. Choice A does all three: average monthly temperature, Lakeview, °F.
3. Choice B makes a cause-and-effect claim (temperature causes seasons) that the data do not show — and that is not scientifically accurate (Earth's tilt causes the seasons).
4. Choice C names the wrong variable: the data are temperatures, not rainfall.
5. Choice D describes only one month, but the graph shows all twelve.

Correct answer: A.

Tip: Titles, axis labels and units are part of expressing scientific information. On the GED, the best title is accurate and complete without adding claims.

Where the answer comes from: the passage says an object "floats in water if its density is less than the density of water, 1.00 g/cm³." The table gives each object's mass and volume.

Step by step:

1. Object A: d = \dfrac{54.0}{20.0} = 2.70 g/cm³. Greater than 1.00 → sinks.
2. Object B: d = \dfrac{18.0}{24.0} = 0.75 g/cm³. Less than 1.00 → floats.
3. Object C: d = \dfrac{89.6}{10.0} = 8.96 g/cm³. Greater than 1.00 → sinks.

Correct answer: B (Object B only).

Notice that Object B has the largest volume but the smallest mass. Floating depends on density (mass per volume), not on size or mass alone.

Tip: Applying a scientific rule means computing the quantity the rule is about (here, density) and then comparing it with the rule's cutoff (1.00 g/cm³).

Where the answer comes from: the table's eight heights: 15, 12, 8, 20, 12, 16, 11, 18 cm.

Step by step:

1. Order them from least to greatest: 8, 11, 12, 12, 15, 16, 18, 20.
2. There are 8 values (an even number), so there are two middle values: the 4th (12) and the 5th (15).
3. The median is their mean: \dfrac{12 + 15}{2} = \dfrac{27}{2} = 13.5 cm.

Correct answer: B (13.5 cm).

Why the others are wrong: 12 cm is the mode (it appears twice). 14 cm is the mean. 16 cm comes from averaging the two middle values of the unsorted list (20 and 12).

Tip: Always sort the data before finding the median. On the GED, one wrong choice is almost always the "middle of the unsorted list."

Evidence: The stem says the flashlight "runs on batteries" and the bulb "shines and becomes warm." Those are the starting and ending forms of energy.

Step by step:

1. A battery stores chemical energy in the substances inside it.
2. When the switch closes, a chemical reaction pushes charges through the wire: chemical energy becomes electrical energy.
3. In the bulb, electrical energy becomes light (radiant) energy. The bulb also gets warm, so some becomes thermal energy.
4. Check with conservation: chemical in = light + heat out. No energy is created or destroyed.

The correct chain is chemical → electrical → light and thermal.

Tip: For any device, ask "What goes in?" and "What comes out?" Then fill in the middle step. Heat almost always appears as an extra output.