A student says, "Once the theory of evolution has been tested enough, scientists will upgrade it to a law." Which response best corrects the student's misconception?

Laws describe observed patterns and theories explain them, so a theory does not turn into a law

Laws are tentative and open to revision, while well-supported theories can no longer change

Theories describe living systems and laws describe physical systems, so the two never overlap

Theories become laws only after enough independent experiments have confirmed their predictions

The template strand of a short gene segment reads 3′-TAC GGA CTC-5′. A mutation changes the eighth base of this template strand from T to A. Selected mRNA codons Codon Amino acid AUG Met (start) CCU Pro GAG Glu GUG Val CAC His UAG Stop Using the codon table, which describes the effect of this mutation on the encoded peptide?

Missense: the third amino acid changes from Glu to Val

Silent: the third amino acid remains Glu

Nonsense: translation stops after Pro

Missense: the third amino acid changes from Glu to His

Why are auroras observed most often at high latitudes?

Earth's magnetic field guides charged solar-wind particles toward the polar regions

Sunlight strikes the polar atmosphere at a low angle and scatters into colored bands

Polar ice sheets reflect sunlight upward, exciting gas molecules in the ionosphere

Ozone is most concentrated over the poles and glows when struck by ultraviolet light

A teacher cracks the shell of a hard-boiled egg and slices it in half to model Earth's interior: shell, white, and yolk. Which feature of Earth is the egg model LEAST able to represent?

The slow convection of mantle rock that moves plates

A thin, rigid outer layer around a thick interior

A dense central region distinct from the material around it

An outer layer broken into separate, fitted pieces

Snapdragon flower color crosses Cross Offspring Red × white (P) All pink (F₁) Pink × pink (F₁ × F₁) 25 red, 52 pink, 23 white (F₂) A student says these results show that the parents' traits blended together. Which response best addresses this misconception?

Red and white reappear in the F₂, so the alleles stayed separate and unchanged

Pink F₁ plants show that red and white alleles merged into a new pink allele

Red and white patches would appear together in the F₂ if blending had occurred

The 1:2:1 ratio shows that two genes interact to produce three flower colors

Praxis General Science (5436)

Free Praxis General Sci 5436 Practice Questions

10 sample questions for the Praxis General Science (5436), with the correct answer and an explanation for each. No account needed. Try each one before you open the answer.

Sections covered on the exam: Nature and Impact of Science and Engineering, Physical Science, Life Science, Earth and Space Science.

Question 1 · Nature and Impact of Science and Engineering
A student says, "Once the theory of evolution has been tested enough, scientists will upgrade it to a law." Which response best corrects the student's misconception?
- A.Laws are tentative and open to revision, while well-supported theories can no longer change
- B.Theories describe living systems and laws describe physical systems, so the two never overlap
- C.Laws describe observed patterns and theories explain them, so a theory does not turn into a law
- D.Theories become laws only after enough independent experiments have confirmed their predictions
Show answer and explanation
Answer: C. Laws describe observed patterns and theories explain them, so a theory does not turn into a law
Scientific laws summarize what happens (often mathematically), while theories are well-tested explanations of why it happens; they are different kinds of knowledge, so no amount of testing converts one into the other. The idea that a theory 'graduates' to a law with enough confirmation is exactly the hierarchy misconception the student holds. Both laws and theories remain open to revision, and both apply across the sciences.
Question 2 · Physical Science
A 200 g metal block at 95 °C is placed in 100 g of water at 20 °C in an insulated cup. The final temperature of both is 25 °C. The specific heat of water is 4.2 J/(g·°C).
Assuming no heat is lost to the surroundings, what is the specific heat of the metal?
- A.0.30 J/(g·°C)
- B.0.11 J/(g·°C)
- C.0.60 J/(g·°C)
- D.0.15 J/(g·°C)
Show answer and explanation
Answer: D. 0.15 J/(g·°C)
The water gains (100 g)(4.2 J/(g·°C))(5 °C) = 2100 J, which equals the heat lost by the metal, so c = 2100 J ÷ (200 g × 70 °C) = 0.15 J/(g·°C). 0.30 results from using 100 g for the metal's mass, 0.60 from swapping the two masses, and 0.11 from using 95 °C instead of the 70 °C temperature drop.
Question 3 · Physical Science
A 500 kg roller-coaster car starts from rest at the top of a 20 m hill and coasts down a track with negligible friction. What is its speed when it is 15 m above the ground? (g = 10 m/s²)
- A.20 m/s
- B.7.1 m/s
- C.10 m/s
- D.17 m/s
Show answer and explanation
Answer: C. 10 m/s
Only the 5 m drop from the start matters: mgΔh = ½mv², so v² = 2gΔh = 2(10)(5) = 100 and v = 10 m/s; the mass cancels. Using the full 20 m height gives 20 m/s, and using the 15 m height above the ground gives √300 ≈ 17 m/s. Omitting the factor of 2 (v² = gΔh) gives about 7.1 m/s.
Question 4 · Life Science
The template strand of a short gene segment reads 3′-TAC GGA CTC-5′. A mutation changes the eighth base of this template strand from T to A.
Selected mRNA codons
Codon Amino acid
AUG Met (start)
CCU Pro
GAG Glu
GUG Val
CAC His
UAG Stop
Using the codon table, which describes the effect of this mutation on the encoded peptide?
- A.Silent: the third amino acid remains Glu
- B.Nonsense: translation stops after Pro
- C.Missense: the third amino acid changes from Glu to His
- D.Missense: the third amino acid changes from Glu to Val
Show answer and explanation
Answer: D. Missense: the third amino acid changes from Glu to Val
The template 3′-TAC GGA CTC-5′ is transcribed to mRNA 5′-AUG CCU GAG-3′ (Met–Pro–Glu). Changing the eighth template base from T to A makes the third template triplet CAC, so the mRNA codon becomes GUG, which codes for Val. Reading CAC directly from the template as if it were the codon gives His, a common error of skipping transcription.
Question 5 · Earth and Space Science
Why are auroras observed most often at high latitudes?
- A.Sunlight strikes the polar atmosphere at a low angle and scatters into colored bands
- B.Polar ice sheets reflect sunlight upward, exciting gas molecules in the ionosphere
- C.Ozone is most concentrated over the poles and glows when struck by ultraviolet light
- D.Earth's magnetic field guides charged solar-wind particles toward the polar regions
Show answer and explanation
Answer: D. Earth's magnetic field guides charged solar-wind particles toward the polar regions
Charged particles from the solar wind are funneled along magnetic field lines that converge near the magnetic poles, where they collide with oxygen and nitrogen in the upper atmosphere and make them emit light. Low-angle sunlight explains long twilight and colorful sunsets, not auroras. Auroras are not produced by ozone or by reflected sunlight; they are strongest during geomagnetic storms, which can also disrupt satellites and radio communication.
Question 6 · Nature and Impact of Science and Engineering
A teacher cracks the shell of a hard-boiled egg and slices it in half to model Earth's interior: shell, white, and yolk.
Which feature of Earth is the egg model LEAST able to represent?
- A.A thin, rigid outer layer around a thick interior
- B.A dense central region distinct from the material around it
- C.The slow convection of mantle rock that moves plates
- D.An outer layer broken into separate, fitted pieces
Show answer and explanation
Answer: C. The slow convection of mantle rock that moves plates
The cracked shell, white, and yolk represent the thin broken crust (plates), the thick mantle, and the distinct core, but a solid hard-boiled egg has no moving material and so cannot show mantle convection, the process thought to drive plate motion. Recognizing what a model omits is as important as recognizing what it shows, which is why the other features, all represented by the egg, are wrong answers.
Question 7 · Physical Science
Given average bond energies of H–H 436 kJ/mol, Cl–Cl 243 kJ/mol, and H–Cl 432 kJ/mol, what is the approximate enthalpy change for H₂(g) + Cl₂(g) → 2HCl(g)?
- A.−185 kJ
- B.+247 kJ
- C.−864 kJ
- D.+185 kJ
Show answer and explanation
Answer: A. −185 kJ
ΔH = energy absorbed breaking bonds − energy released forming bonds = (436 + 243) − 2(432) = 679 − 864 = −185 kJ, so the reaction is exothermic. +185 kJ reverses the subtraction, +247 kJ counts only one H–Cl bond (679 − 432), and −864 kJ counts only the energy released in forming the H–Cl bonds, ignoring the energy needed to break H–H and Cl–Cl.
Question 8 · Physical Science
A worker pushes a 400 N crate at constant speed up a ramp 5.0 m long to a platform 1.0 m high, applying 100 N parallel to the ramp. What is the ramp's efficiency?
- A.25%
- B.80%
- C.20%
- D.75%
Show answer and explanation
Answer: B. 80%
Useful work output is the crate's weight times the height: 400 N × 1.0 m = 400 J. Work input is the applied force times the ramp length: 100 N × 5.0 m = 500 J, so efficiency = 400 ÷ 500 = 80% (equivalently, AMA 4 ÷ IMA 5). The 25% comes from dividing force by weight, and 20% is the reciprocal of the ideal mechanical advantage.
Question 9 · Life Science
Snapdragon flower color crosses
Cross Offspring
Red × white (P) All pink (F₁)
Pink × pink (F₁ × F₁) 25 red, 52 pink, 23 white (F₂)
A student says these results show that the parents' traits blended together. Which response best addresses this misconception?
- A.Red and white reappear in the F₂, so the alleles stayed separate and unchanged
- B.Pink F₁ plants show that red and white alleles merged into a new pink allele
- C.Red and white patches would appear together in the F₂ if blending had occurred
- D.The 1:2:1 ratio shows that two genes interact to produce three flower colors
Show answer and explanation
Answer: A. Red and white reappear in the F₂, so the alleles stayed separate and unchanged
Under blending, the pink F₁ would breed true and the F₂ would be all pink. The return of red and white in about a 1:2:1 ratio (25:52:23) shows one gene with two incompletely dominant alleles that segregate intact, with heterozygotes appearing pink. Patches of both colors would indicate codominance, and two interacting genes would give 16-part ratios such as 9:3:4.
Question 10 · Earth and Space Science
What is the maximum altitude of the Sun above the horizon at local noon on the December solstice at latitude 35° N?
- A.11.5°
- B.78.5°
- C.31.5°
- D.55.0°
Show answer and explanation
Answer: C. 31.5°
On the December solstice the Sun is directly overhead at 23.5° S, so the angular distance from 35° N is 35 + 23.5 = 58.5°, and the noon altitude is 90 − 58.5 = 31.5°. Subtracting 23.5° from the latitude gives 11.5°, the equinox value is 90 − 35 = 55.0°, and 78.5° is the June solstice altitude.

Selected mRNA codons
Codon	Amino acid
AUG	Met (start)
CCU	Pro
GAG	Glu
GUG	Val
CAC	His
UAG	Stop

Snapdragon flower color crosses
Cross	Offspring
Red × white (P)	All pink (F₁)
Pink × pink (F₁ × F₁)	25 red, 52 pink, 23 white (F₂)

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