NAS 2 CHALLENGE FINAL PAPER QUESTIONS AND
ANSWERS GUARANTEE A+ 2025/2026
✔✔spinal/vertebral - ✔✔spinal cord body region
✔✔thoracic cavity - ✔✔lungs, heart, esophagus, trachea, thymus
✔✔abdominal cavity - ✔✔stomach, liver, spleen, gallbladder, small/large intestines,
kidneys
✔✔pleural cavity - ✔✔contains lungs
✔✔pelvic cavity - ✔✔end of large intestines, urinary bladder, reproductive organs
✔✔mediastinum - ✔✔seperates lungs
✔✔pericardial - ✔✔contains heart
✔✔axial - ✔✔head, neck, and trunk of body
✔✔appendicular - ✔✔limbs
✔✔electron - ✔✔negatively charged particle, outer shell
✔✔proton - ✔✔positive, in nucleus
✔✔number of protons - ✔✔number of electrons is equal to the same...
✔✔number of protons - ✔✔atomic number is equal to...
✔✔atomic mass - ✔✔sum of protons and neutrons in the nucleus
the weighted average mass of isotopes of an element, found below the element symbol
✔✔ionic bond - ✔✔chemical bond formed between two ions that are opposite charges,
atom gives up one or more electrons to another atom
✔✔covalent bond - ✔✔sharing electron pairs between atoms
✔✔polar covalent bond - ✔✔pair of electrons unequally shared between two atoms
✔✔nonpolar covalent bond - ✔✔two atoms share a pair of electrons with each other
, ✔✔hydrogen bond - ✔✔weak bond result of attraction between proton and
electronegative atom of another
✔✔enzymes - ✔✔catalyze chemical reactions by lowering activation energy barriers
and converting substrate molecules to products
✔✔substrate - ✔✔reactant acted upon by an enzyme
enzymes active site binds to this
✔✔active site - ✔✔part of an enzyme to which substrates bind and where a reaction is
catalyzed
✔✔enzymes - ✔✔promote chemical reactions by bringing substrates together in an
optimal orientation, thus creating an ideal chemical environment for the reaction to
occur
always return to original state
✔✔decomposition - ✔✔single compound breaks down into two or more elements or
new compounds
These reactions often involve heat, light, electricity
✔✔synthesis - ✔✔multiple reactants combine to form a single product
Release energy in form of heat and light (exothermic)
Hydrogen and oxygen -> water
✔✔exchange - ✔✔any class of reactions between two substances that involves an
exchange of one or more ionic components (positive and negative charges)
✔✔solvent - ✔✔substance solute is dissolved in
✔✔polar molecule - ✔✔a molecule that has electrically charged areas
covalent bonds - polarity if its atoms differ in electronegativity
can form hydrogen bonds
✔✔nonpolar molecule - ✔✔cannot mix with water
✔✔dissociation - ✔✔leads to acidic and basic conditions
ANSWERS GUARANTEE A+ 2025/2026
✔✔spinal/vertebral - ✔✔spinal cord body region
✔✔thoracic cavity - ✔✔lungs, heart, esophagus, trachea, thymus
✔✔abdominal cavity - ✔✔stomach, liver, spleen, gallbladder, small/large intestines,
kidneys
✔✔pleural cavity - ✔✔contains lungs
✔✔pelvic cavity - ✔✔end of large intestines, urinary bladder, reproductive organs
✔✔mediastinum - ✔✔seperates lungs
✔✔pericardial - ✔✔contains heart
✔✔axial - ✔✔head, neck, and trunk of body
✔✔appendicular - ✔✔limbs
✔✔electron - ✔✔negatively charged particle, outer shell
✔✔proton - ✔✔positive, in nucleus
✔✔number of protons - ✔✔number of electrons is equal to the same...
✔✔number of protons - ✔✔atomic number is equal to...
✔✔atomic mass - ✔✔sum of protons and neutrons in the nucleus
the weighted average mass of isotopes of an element, found below the element symbol
✔✔ionic bond - ✔✔chemical bond formed between two ions that are opposite charges,
atom gives up one or more electrons to another atom
✔✔covalent bond - ✔✔sharing electron pairs between atoms
✔✔polar covalent bond - ✔✔pair of electrons unequally shared between two atoms
✔✔nonpolar covalent bond - ✔✔two atoms share a pair of electrons with each other
, ✔✔hydrogen bond - ✔✔weak bond result of attraction between proton and
electronegative atom of another
✔✔enzymes - ✔✔catalyze chemical reactions by lowering activation energy barriers
and converting substrate molecules to products
✔✔substrate - ✔✔reactant acted upon by an enzyme
enzymes active site binds to this
✔✔active site - ✔✔part of an enzyme to which substrates bind and where a reaction is
catalyzed
✔✔enzymes - ✔✔promote chemical reactions by bringing substrates together in an
optimal orientation, thus creating an ideal chemical environment for the reaction to
occur
always return to original state
✔✔decomposition - ✔✔single compound breaks down into two or more elements or
new compounds
These reactions often involve heat, light, electricity
✔✔synthesis - ✔✔multiple reactants combine to form a single product
Release energy in form of heat and light (exothermic)
Hydrogen and oxygen -> water
✔✔exchange - ✔✔any class of reactions between two substances that involves an
exchange of one or more ionic components (positive and negative charges)
✔✔solvent - ✔✔substance solute is dissolved in
✔✔polar molecule - ✔✔a molecule that has electrically charged areas
covalent bonds - polarity if its atoms differ in electronegativity
can form hydrogen bonds
✔✔nonpolar molecule - ✔✔cannot mix with water
✔✔dissociation - ✔✔leads to acidic and basic conditions
