Science Quiz with Answers | Grade 12 - 20 MCQs with Explanations

Science Quiz with Answers | Grade 12 AP Level Test

Free Grade 12 Science Quiz with answers! 20 AP-level questions: physics, chemistry, biology. Ohm’s Law, DNA polymerase, mass-energy equivalence. 70% PASS for college prep. High school senior review!

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Grade 12 Science Quiz Questions with answers Free

Grade 12 science quiz with detailed answers covering AP physics (Ohm’s Law), chemistry (electronegativity), biology (mitochondria). 20 textbook-style questions for senior year review and college prep!

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#1. What is the approximate acceleration due to gravity experienced on the surface of Earth’s Moon?

1.62 m/s²

9.8 m/s²

3.7 m/s²

4.9 m/s²

Explanation: Moon’s mass = 1/81 Earth’s; radius = 1/4 Earth’s → gₘₒₒₙ = gₑₐᵣₜₕ/6.

#2. What is the SI unit used to measure electrical resistance in a circuit?

Ohm

Volt

Ampere

Watt

Explanation: Ohm (Ω) quantifies opposition to current flow per Ohm’s Law: V=IR. Essential circuit analysis.

#3. How many total chromosomes are present in a typical human diploid somatic cell?

Explanation: 22 homologous autosomal pairs + 1 sex chromosome pair (XX or XY).

#4. Which element exhibits the highest electronegativity value on the Pauling scale?

Neon

Chlorine

Fluorine

Oxygen

Explanation: Fluorine (χ = 4.0) strongest electron attractor due to small size, high nuclear charge.

#5. Which cellular organelle serves as the primary site for ATP production through cellular respiration?

Chloroplast

Mitochondria

Endoplasmic reticulum

Nucleus

Explanation: Inner mitochondrial membrane houses electron transport chain, ATP synthase.

#6. Lenz’s Law specifically describes which fundamental physical phenomenon?

Gravitational attraction

Light refraction

Heat transfer

Opposition of induced EMF to change in magnetic flux

Explanation: Induced current creates opposing magnetic field (Faraday’s corollary). Key electromagnetism principle.

#7. Which photosynthetic pigment absorbs light most efficiently at 430nm and 662nm wavelengths?

Carotenoids

Phycocyanin

Chlorophyll a

Chlorophyll b

Explanation: Primary reaction center pigment in photosystems I & II.

#8. What is the dimensional formula for electrical resistance derived from base SI units?

MLT⁻²

[ML²T⁻²A⁻¹]

ML²T⁻³A⁻²

M⁰L⁰T⁰A⁰

Explanation: R = V/I = (Work/Charge)/(Charge/Time) = ML²T⁻³A⁻².

#9. In human nephrons, the initial filtration of blood plasma occurs specifically within which structure?

Collecting duct

Proximal tubule

Bowman's capsule

Loop of Henle

Explanation: Glomerulus hydrostatic pressure forces filtrate through filtration membrane.

#10. Which pancreatic hormone specifically lowers elevated blood glucose levels after meals?

Somatostatin

Growth hormone

Glucagon

Insulin

Explanation: Insulin ↑ GLUT4 transporters → glucose uptake by muscle/adipose tissue.

#11. Which factor has the greatest influence on increasing the rate of a typical chemical reaction?

Concentration

Catalyst presence

Surface area

Temperature elevation

Explanation: 10°C ↑ doubles rate (rule of thumb); activation energy barrier ↓ (Arrhenius).

#12. What is the standard numerical range of the pH scale used in aqueous solutions?

0-10

0-14

1-12

1-14

Explanation: pH = -log[H⁺]; 7=neutral, <7=acidic, >7=basic.

#13. Which enzyme catalyzes the formation of new DNA strands during replication?

DNA polymerase

Ligase

RNA polymerase

Primase

Explanation: Adds nucleotides 5’→3′ direction using template strand.

#14. Newton’s First Law of Motion is also known by which classical name?

Law of Inertia

Gravitational Law

Law of Acceleration

Third Law of Motion

Explanation: Objects maintain uniform motion unless acted upon by net force.

#15. Which periodic table group contains the most reactive nonmetal elements?

Group 14

Group 15

Group 17

Group 18

Explanation: Halogens (F, Cl, Br, I) gain 1 electron to complete octet.

#16. In a step-up transformer, which electrical quantity specifically increases across the secondary coil?

Frequency

Voltage potential

Current flow

Power output

Explanation: Vₛ/Vₚ = Nₛ/Nₚ (turns ratio). Power conserved: P=VI constant.

#17. The molecular structure of ozone (O₃) demonstrates which specific type of isomerism?

Metamerism

Resonance hybridization

Geometric isomerism

Tautomerism

Explanation: Delocalized π electrons across three oxygen atoms; equivalent structures.

#18. Which fat-soluble vitamin is primarily synthesized in human skin upon ultraviolet exposure?

Vitamin E

Vitamin D

Vitamin K

Vitamin A

Explanation: UVB converts 7-dehydrocholesterol → cholecalciferol (vitamin D₃).

#19. Which nitrogenous base replaces thymine in RNA molecular structure?

Uracil

Cytosine

Adenine

Guanine

Explanation: RNA: A-U, G-C pairing; DNA: A-T, G-C.

#20. Ethanol (C₂H₅OH) and dimethyl ether (CH₃OCH₃) represent which type of constitutional isomerism?

Position

Chain branching