Question 1 of 10
A student designed an experiment to test how light affects plant growth. Identify the components of this experiment. 
AIndependent: temperature; Dependent: light
BIndependent: water; Dependent: soil
CIndependent: plant height; Dependent: light
DIndependent: light; Dependent: plant height
Explanation
📌 Independent variable = what you change (light)
Dependent variable = what you measure (plant height)
Control group = no light (to compare against)
Constants = same soil, water, temperature, pot size
Dependent variable = what you measure (plant height)
Control group = no light (to compare against)
Constants = same soil, water, temperature, pot size
Question 2 of 10
The graph shows the change in a moth population over time. Dark moths increased after industrial pollution darkened tree bark. This is an example of:
ASpontaneous generation
BGenetic engineering
CArtificial selection
DNatural selection
Explanation
📌 This is the classic peppered moth example of natural selection.
Before pollution: light bark → light moths camouflaged → survived
After pollution: dark bark → dark moths camouflaged → survived
The environment selected for the trait that provided camouflage.
Before pollution: light bark → light moths camouflaged → survived
After pollution: dark bark → dark moths camouflaged → survived
The environment selected for the trait that provided camouflage.
Question 3 of 10
The image shows lab equipment. Which is used to measure precise volumes of liquid? 
AGraduated cylinder
BTest tube
CErlenmeyer flask
DBeaker
Explanation
A graduated cylinder is designed for accurate volume measurement (markings are precise). Beakers and flasks are for rough volumes only.
Question 4 of 10
In a DNA nucleotide, which component carries the genetic code through its specific sequence?
AHydrogen bond
BPhosphate group
CDeoxyribose sugar
DNitrogenous base
Explanation
The nitrogenous base (adenine, thymine, guanine, or cytosine) is the part of a DNA nucleotide that varies — its sequence along the strand IS the genetic code. The phosphate and deoxyribose sugar are identical in every nucleotide and form the structural 'backbone' of the DNA strand; they don't store information. Hydrogen bonds hold the two strands together at the bases but are not part of a single nucleotide.
Question 5 of 10
A rabbit's strong hind legs allow it to escape predators by running quickly. This is BEST classified as which type of adaptation?
APhysiological — an internal chemical or metabolic process
BStructural — anatomical feature inherited and present in the body
CMimicry — resembling another organism for defense
DBehavioral — an inherited action pattern the animal performs
Explanation
The rabbit's hind legs are an anatomical body feature — a structural adaptation. Structural adaptations are physical body parts (legs, claws, fur, beaks) inherited through generations. Distractors: Behavioral would be the act of running away (a pattern of action), not the legs themselves. Physiological refers to internal processes like blood pressure or hormone release, not external anatomy. Mimicry is a specific case where one organism resembles another for defense, which doesn't apply here.
Question 6 of 10
Which graph correctly shows exponential growth?
AA
BNeither
CBoth
DB
Explanation
📌 Exponential growth = J-shaped curve (slow start, rapid increase)
Linear growth = straight line (constant rate)
Graph A shows exponential growth.
Linear growth = straight line (constant rate)
Graph A shows exponential growth.
Question 7 of 10
Which organelle is labeled X in the cell diagram below? 
ANucleus
BEndoplasmic reticulum
CMitochondria
DGolgi apparatus
Explanation
📌 Organelle X has the bean-shaped structure with inner folds (cristae) → Mitochondria
Mitochondria = powerhouse of the cell = produces ATP through cellular respiration
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
Mitochondria = powerhouse of the cell = produces ATP through cellular respiration
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
Question 8 of 10
All three domains of life (Bacteria, Archaea, and Eukarya) share which structural feature?
AChloroplasts for photosynthesis
BMulticellular organization
CRibosomes for protein synthesis
DA membrane-bound nucleus
Explanation
All cellular life — Bacteria, Archaea, and Eukarya — uses ribosomes to build proteins. Distractors: a membrane-bound nucleus is found only in Eukarya (Bacteria and Archaea are prokaryotic). Multicellularity appears only in some Eukarya — most life is unicellular. Chloroplasts are organelles found only in plants and algae (a subset of Eukarya).
Question 9 of 10
The diagram shows the three domains of life. Which domain contains organisms with no membrane-bound nucleus and lives in extreme environments?
APlantae
BArchaea
CEukarya
DBacteria
Explanation
Archaea are prokaryotes (no nucleus) and many live in extreme environments (hot springs, salt lakes, deep-sea vents). Bacteria are also prokaryotes but typically not extremophiles.
Question 10 of 10
The image shows the taxonomic hierarchy. Which level contains organisms most similar to each other? 
ASpecies
BClass
CKingdom
DDomain
Explanation
Species is the most specific (narrowest) level — organisms in the same species can interbreed and produce fertile offspring.