125 terms

7th Grade Science: 2018 Semester 2 Exam Set

Vocabulary list for the 7th grade chemical experimental design module
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chemical bond
An attractive force that holds together the atoms in a molecule.
covalent bond
chemical bond formed when two atoms share one or more electrons
ionic bond
chemical bond formed when one atom gains and a second atom loses electrons
single displacement
a reaction in which one element takes the place of another element in a compound
double displacement
a reaction where 2 reactants exchange places
decomposition reaction
a reaction where the compound breaks down to form two or more simpler substances
synthesis reaction
a reaction in which two or more substances combine to form a new compound
endothermic
a chemical reaction that absorbs energy
exothermic
A chemical reaction that releases energy
precipitate
a solid that forms as a result of mixing two solutions
acid
a chemical substance that is corrosive is tart or sour-tasting and has a pH of less than 7
base
a chemical substance that feels slippery when dissolved in water, is bitter tasting, and has a pH greater than 7
pH
a measure of how acid or basic a solution is
Auditory cortex
a section of the brain that receives and processes auditory (sound) signals from the ear.
Cerebrum
the "wrinkly" area that forms most of the outer part of the brain.
Gustatory cortex
a section of the brain that receives and processes taste signals from the mouth and tongue.
Hypothalamus
a section of the brain, located below the thalamus, that controls many unconscious functions including body temperature, thirst, hunger, and sleep.
Nerve impulse
a signal that is transmitted along a nerve fiber.
Neural pathway
a series of connected nerves along which an electrical impulse travels through the body.
Neuron
a cell that is able to transmit neural impulses (signals) from one part of the body to another.
Olfactory cortex
a section of the brain that receives and processes olfactory (smell) signals from the nose.
Olfactory bulb
a structure located above the nose that receives signals from the sensory neurons in the nose and sends those signals to the olfactory cortex in the brain for processing.
Optic nerve
a nerve behind the eye that transmits signals from the retina to the brain.
Sensory neuron
a neuron that converts stimuli from the environment to internal electrical signals.
Somatosensory cortex
a section of the brain that receives and processes sensory stimuli from the skin, muscles and joints.
Spinal cord
a bundle of neurons inside the spine that connects nearly all parts of the body below the head to the brain.
Stimulus
a detectable change in the internal or external environment.
Thalamus
a part of the brain through which sensory impulses are passed before reaching the cerebral cortex.
Visual cortex
a section of the brain at the back of the head that receives and processes visual (light) signals from the eye.
Artery
a blood vessel that carries blood away from the heart.
Atrium
either of the two upper chambers of the heart that receives blood from veins.
Blood vessel
a tube in the body through which blood flows.
Capillary
a tiny blood vessel which exchanges oxygen, glucose, and other materials with body cells.
Circulatory System
Includes the heart, blood vessels, and blood which transports oxygen, nutrients, and other materials to body cells and also removes carbon dioxide, urea, and other wastes from body cells.
Platelet
a small blood cell fragment that helps the blood to clot.
Pulmonary artery
carries blood from the right ventricle to the lungs.
Pulmonary vein
carries blood from the lungs to the left atrium.
Red blood cell
carries oxygen throughout the body.
Urea
waste product in the blood that comes from the breakdown of proteins.
Ventricle
either of the two lower chambers of the heart that pumps blood through arteries.
Vein
a blood vessel that carries blood to the heart.
White blood cell
cell that fights infection by destroying microscopic, disease causing organisms
Absorption
the taking in of one substance by another, refers to the passage of nutrients and water through the walls of the small and large intestines.
Chemical digestion
chemical breakdown of nutrients through the action of enzymes and other substances.
Chyme
a thick liquid of partially digested food produced by the stomach.
Digestion
the breakdown of food into simpler components that can be absorbed and used by the body.
Digestive system
a group of organs that work together to break down and absorb nutrients from food, as well as eliminate the resulting wastes.
Enzyme
a molecule, usually a protein, which speeds up a chemical reaction.
Fiber
plant material in food that is difficult to digest.
Food Calorie
a unit used to measure the energy in foods.
Mechanical digestion
physical breakdown of foods, including mechanical digestion (chewing in the mouth and churning in the stomach)
Nutrient
a substance that is used by the body for energy, growth, or other processes essential to life.
Peristalsis
wavelike muscle contractions that push food through the digestive system.
Villus
tiny, finger-like projection in the wall of the small intestine where nutrients and water are absorbed
Stomach
large muscular sac that continues the mechanical and chemical digestion of food
Small Intestine
Digestive organ where most chemical digestion and absorption of food takes place
Large Intestine
Digestive organ that absorbs water and forms feces
Mouth
First digestive organ that initiates mechanical digestion and chemical digestion of carbohydrates
Evidence of a Chemical Reaction
color change, energy (temperature) change, a gas is produced (bubbling), a precipitate (solid) forms, or light is released.
chemical reaction
A process in which bonds between atoms are broken and new bonds are formed producing substances which are different from the starting materials.
reactants
the substances that you start with in a chemical reaction
products
the new substances that are formed in a chemical reaction
compound
a pure substance that contains atoms of two or more different kinds of elements combined in a fixed ratio.
physical change
A process in which some properties of a substance change, but atoms are NOT rearranged and no new substances are formed.
chemical bond
An attractive force that holds together the atoms in a molecule.
chemical formula
a shorthand way using letters and numbers to show which elements are in a compound
chemical equation
writing symbols to represent the reactants and products in a chemical reaction
indicator
a substance used to show the presence of something or that a reaction has happened, for example, a substance that changes color when placed in an acid or base
catalyst
a substance that speeds up a chemical reaction
coefficient
regular sized numbers in front of molecules or atoms that tell how many copies there are in an equation
precipitate
a solid that forms as a result of mixing two solutions
molecule
a pure substance made up of two or more atoms which are combined in a constant ratio and held together by chemical bonds. The substance may have two of the same type of atoms (elements) or two different types of atoms (compounds).
substance
A single kind of matter that is pure and has a specific set of properties
element
a pure substance made up of only one type of atom; it cannot be broken down into simpler substances
mixture
A combination of two or more substances (can be atoms, molecules, ions, isotopes, etc.) that are not chemically combined
physical change
A process in which some properties of a substance change, but atoms are NOT rearranged and no new substances are formed.
boiling point
The temperature at which a liquid changes to a gas
conductivity
A material's ability to allow heat or electric charges to flow.
solid
Particles arranged such that their shape and volume are relatively stable. The particles are packed closely together in stable positions.
liquid
Particles that are in constant contact but move freely among themselves. The particles can rearrange to take the shape of their container, but the total volume remains constant.
gas
Particles that are not connected to one another and move freely in all directions. The particles separate in all directions, expanding to fill their container changing both shape and volume.
plasma
Gas particles in which the electrons have been removed from their atoms resulting in an electrically neutral "soup" of both positive and negative particles. Examples are neon signs and lightning
Density
A measure of how much mass is contained in a given volume
subscript
a number that tells how many atoms of each element are in a molecule
Walter Fleming
scientist that studied mitosis in 1882
Van Beneden
scientist that studied meiosis in 1887
Weissman
scientist that proposed mechanism for meiosis
meiosis
process in which the number of chromosomes is reduced by half to produce gametes
mitosis
process in which the nucleus divides in two daughter cells containing the same number of chromosomes as the parent
diploid
a cell having two copies of each chromosome; normal cells that have chromosomes from each parent
gamete
a haploid sex cell, formed during meiosis
haploid
a cell having one copy of each chromosome; such as a gamete produced by meiosis
chromosome
threadlike structure in the nucleus containing the genetic information that is passed from one generation of cells to the next
gene
a DNA sequence that codes for specific proteins which helps determine many traits of living things
RNA
ribonucleic acid; cell molecules that are created to carry the code from the nucleus to the cytoplasm (messenger) and that can bring amino acids to the ribosome (transfer) for protein production
nucleotide
The building block of DNA and RNA
messenger RNA (mRNA)
molecule that carries the coded message from DNA in the nucleus to the ribosome in the cytoplasm; mRNA
transfer RNA (tRNA)
molecule that carries amino acids to the ribosome so they can be matched to the code on the mRNA
codon
a specific sequence of three bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid
anticodon
group of three bases on a tRNA molecule that pairs with the mRNA codon
replication
the process in which DNA makes a copy of itself before cell division
translation
the process in which the code on mRNA is used to make protein
transcription
the process in which DNA is copied to make RNA
Heredity
the passing of traits from parent to offspring
genetics
The scientific study of heredity
allele
the different forms of a gene
trait
a characteristic that an organism can pass on to its offspring through its genes.
purebred
an organism that always produces offspring with the same form of a trait as the parent
hybrid
an organism that has more than one type of allele for a trait
phenotype
physical characteristics of an organism
genotype
genetic makeup of an organism
dominant
trait that will show up in an organism's phenotype if gene is present
(CAPITALS - A, B, C, Y, R, etc.)
recessive
trait that can be masked by the dominant allele
(lowercase - a, b, c, y, r, etc.)
homozygous
having two identical alleles for a trait
heterozygous
having two different alleles for a trait
incomplete dominance
the phenotype results in a blend of two different alleles: ex, red flowers x white flowers result in pink flower offspring
Punnett Square
a chart that shows all the possible combinations of alleles that can result from a genetic cross
codominant
traits that are both seen when they are present.
probability
the chances that a particular event will occur
DNA
deoxyribonucleic acid, the material that contains the information that determines inherited characteristics
Acquired trait
a trait that IS NOT passed down from parents to their offspring. examples include dyed hair, pierced ears, broken bones, and scars
Asexual reproduction
reproduction in which one parent produces offspring without fertilization of an egg cell. the offspring, called clones, are identical
Offspring
a new organism produced by either asexual or sexual reproduction
Sexual reproduction
reproduction caused by the fertilization of an egg cell.
Inherited trait
a trait that IS passed down from parents to their offspring. examples include skin color, eye color, extra digits and many others.

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