ACT Science Outside Knowledge Cheat Sheet
While the ACT Science Test primarily tests your ability to evaluate and interpret various
scientific experiments and their corresponding data, there are a few questions on each test
that require some outside scientific knowledge to answer correctly. This may seem like a very
small portion of the test and therefore not worth the effort for you to study, so here are some
key points to convince you otherwise!
Outside Knowledge Helps with Timing!
Outside knowledge is primarily used in very simple data interpretation questions in order
to make them a bit more difficult. You can usually use outside knowledge to eliminate wrong
answer choices (usually two of them)
without
consulting passages, tables or figures. If you
don’t know the outside knowledge, you might be tempted to consult the passage in an attempt
to find that information (Spoiler Alert: it’s not there!), which is an absolute KILLER for timing.
If you know the outside knowledge, these questions should take you mere seconds and help
you finish all 40 questions in time!
One Extra Correct Answer Can Make A Huge Difference!
Because the ACT Science Scale is so steep, one extra question correct almost always
equates to one extra point on your scale score. In some instances, it can even add two points to
your scale score!
Effort-Based Points are Hard to Come By!
Questions that test outside knowledge are the only types of questions on the ACT Science
Test that you can prepare for fully in advance, and these questions are usually pretty easy if
you know the outside knowledge. They are essentially free points if you study this document!
The ESM Curriculum Team has pored over every released ACT Science Test from the past 15
years to develop a comprehensive set of outside knowledge needed on any future test (though
other concepts may come up on future tests). In addition, we have included just enough
knowledge on each concept to ensure you get a question right on test day! To use this
document most effectively:
1. Read through the entire document and highlight any concepts that you don’t know
well.
2. Quiz yourself on these concepts, continuing to eliminate the ones you know well.
3. Rinse and repeat Step 2 until there are no unfamiliar concepts remaining!
General Sciences
Components of Scientific Experiments
Independent Variable:
A variable (often on !-axis of a graph) that you are changing on
purpose to see its effect on another variable.
Dependent Variable:
A variable (often on "-axis of a graph) whose value depends on the
independent variable.
Control:
An unchanged element throughout an experiment that allows the
relationship between other variables to be better understood.
Accuracy:
How close a measured value or values is/are to the actual value.
Precision:
How close measured values are to each other.
Units of Metric System
Length (meters)
Mass (grams)
Volume (Liters)
1 meter (m) = .001 kilometers (km)
1 gram (g) = .001 kilograms (kg)
1 liter (L) = .001 kiloliters (kL)
1000 m = 1 km
1000 g = 1 kg
1000 L = 1 kL
1 m = 100 centimeters (cm)
1 g = 100 centigrams (cg)
1 L = 100 centiliters (cL)
.01 m = 1 cm
.01 g = 1 cg
.01 L = 1 cL
1 m = 1000 millimeters (mm)
1 g = 1000 milligrams (mg)
1 L = 1000 milliliters (mL)
.001 m = 1 mm
.001 m = 1 mg
.001 L = 1 mL
Miscellaneous Math Formulas
Percentage Equation:
# $
%&'(
)*+,-
./00
Percent Error:
1
2-&34'-5 6-!&7(
-!&7(
1
./00#
Average Equation:
3428+98:&,4-3
;8+98:&,4-3
Slope Equation:
"
!
6"
"
!
!
6!
"
Temperature Conversions
Celsius to Fahrenheit:
< $
=
>
? @AB
Celsius to Kelvin:
C $ ? @BDA
? $ C 6BDA
Fahrenheit to Celsius:
? $
>
=
E< 6ABF
Biology
Cellular Biology
Lysosomes:
Digest food and break down cell components with enzymes
Mitochondria:
Powerhouses of the cell that produce ATP.
Cell Nucleus:
Brain of the cell. Contains genetic information
Ribosomes:
Organelle that translates mRNA to protein
Cell membrane:
The semipermeable membrane containing the cytoplasm of a cell.
Plant Cells vs. Animal Cells:
Plant cells have a cell wall, chloroplasts, and vacuoles.
Chloroplasts:
Organelle containing chlorophyll where photosynthesis takes place.
Cellulose:
Exists in plants (not in animals) and is part of their cell walls.
Cholesterol:
Exists in animals and is part of their cell membranes.
Photosynthesis:
(Plant Cells Only) The process of converting carbon dioxide and water into
nutrients and oxygen.
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!
@LN
!
M J ?
#
N
"!
M
#
@LM
!
Cellular Respiration:
The process plants and animals use to convert fuel (nutrients) into energy (ATP)
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?
#
N
"!
M
#
@LM
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Prokaryotes vs Eukaryotes:
Two types of unicellular organisms. Prokaryotes lack a defined nucleus, while
Eukaryotes have a defined nucleus.
Amoeba:
Eukaryotic, unicellular organisms with a nucleus.
Ecology
Order of Biological
Classification:
(Domain), Kingdom, Phylum, Class, Order, Family, Genus, Species
Producers/Autotrophs:
Organisms that can make their own food for energy
Consumers/Heterotroph:
Organisms that must consume others for nutrients
Detritivores:
Organisms that feed on dead organic material.
Trophic level:
A position on the food chain. Organisms on same trophic level have similar
feeding 'modes'.
Genetics/Sexual Reproduction
Gametes:
Sex cells that combine to form zygote (fertilized egg). Each gamete holds 23
of the 46 chromosomes.
Sex-Linked Traits:
Traits associated with genes found on sex chromosomes
Protein Synthesis:
Entire process of converting DNA to mRNA to proteins.
Other explanation: Transcription + Translation
Transcription:
Process of copying DNA to mRNA
Translation:
Process of reading mRNA and synthesizing proteins.
DNA:
Carrier of genetic information and blueprint for protein synthesis
mRNA:
Convey genetic information from DNA to ribosomes, which facilitate protein
production.
Genes:
Unit of heredity transferred from parent to offspring that determines some
characteristics of the offspring.
Alleles:
One of the possible variations of a gene. Typically, each gene has 2 alleles.
Alleles can be dominant or recessive.
Heterozygous Alleles:
Two different alleles (one dominant and recessive).
Examples: O& and &O
Homozygous Alleles:
Two copies of the same allele (both dominant or both recessive).
Examples:
OO
(dominant) and
&&
(recessive)
Dominant Traits:
Expressed in an offspring through a dominant allele (OO or O&F.
Recessive Traits:
Only expressed in offspring if homogenous (&&F.
Biochemistry
Fats:
Made up of Carbon (C), Hydrogen (H), and Oxygen (O), with carbon as the
most prominent element.
Amino Acids:
Building block of protein. N-C-O backbone.
Proteins:
Chains of amino acids.
Nucleic Acids:
Building block of DNA/RNA. Have nitrogenous base, sugar group, and
phosphate group.
Chemistry
Miscellaneous Chemistry
Solubility:
Ability of a given substance (solute) to dissolve in a solvent
Solutions vs. Mixtures:
Solutions are homogenous (same uniform appearance).
Mixtures are heterogenous (consists of visibly different substances)
Concentration of
Solution:
Amount of substance per unit of space. (
$%&'(
)*+,%
P
'-),(
)*+,%
P%%2F
Basics of Gas Laws:
At constant temperature, volume and pressure are inversely proportional.
At constant pressure, temperature and volume are directly proportional.
At constant volume, temperature and pressure are directly proportional.
pH Scale:
/ Q %N Q D J Acidic
%N $ D J Neutral (water has %N of 7)
D Q %N Q /R J Basic
pH Meter
Bromothymol Blue
Litmus Paper
Phenolphthalein:
All can be used to measure pH
Phase Changes
Phase Changes:
Solid - temperature less than freezing/melting point
Liquid – temperature above freezing/melting but below boiling point
Gas – temperature above boiling point
Kinetic Molecular Theory
of Matter:
Particles have least energy, and are closest together, in solids
Particles have most energy, and are farthest apart, in gases.
Boiling/Freezing Point of
Water:
Water freezes (liquid to solid) and melts (solid to liquid) at 0S / ABT
Water is a liquid between 06/00S8U8AB6B/BT
Water boils (liquid to gas) or condenses (gas to liquid) at /00S / B/BT
Density:
Density is mass per unit of volume (D = m/v).
Objects
more dense
than surrounding fluid
sink
.
Objects
less dense
than surrounding fluid
float
.
Usually solid J liquid J gas goes most to least dense
Basic Molecular Structure
Protons:
Positively charged (@/) subatomic particles present in the nucleus.
Mass V /8&24
Neutrons:
Neutrally charged (0F subatomic particles present in the nucleus.
Mass V /8&24
Electrons:
Negatively charged (6/) subatomic particles that orbit the nucleus in clouds
Mass V
"
!...
8&24
Chemical Equations & Reactions
Chemical Equations:
Reactants
J
Products
Balancing Chemical
Equations:
Number of atoms of each element MUST be equal on both sides of equation
(conservation of mass and energy).
Add coefficients to ensure both sides are balanced!
Molar Mass:
Mass of 1 mole of atoms/molecules for a particular element/molecule
Avogadro's Number:
L8!8/0
!/
, used to model number of atoms or molecules in one mole of a
substance
Endothermic Reaction:
A chemical reaction that absorbs heat from its surroundings, leaving the
container of the reaction feeling cold.
Exothermic Reaction:
A chemical reaction that releases heat into its surroundings, leaving the
container for the reaction feeling hot.
Physics
Directional Forces:
Gravity points downward.
Friction/drag/resistance point in opposite direction of an object’s motion.
Buoyancy points up
Mass vs. Weight:
Weight depends on the force of gravity (on Earth, =WX82U3
!
)
Magnetism:
Like charges repel; opposite charges attract.
Astronomy
Order From Sun:
Mercury J Venus J Earth J Mars J Jupiter J Saturn J Uranus J Neptune
Relative Masses of Planets:
Jupiter Y Saturn Y Neptune Y Uranus Y Earth Y Venus Y Mars Y Mercury
