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7th Grade Science Content Vocabulary
Key Terms
Introduction to Life:
unicellular - Having or consisting of one cell; one-celled
multicellular - Having or consisting of many cells
energy - The ability of one system to do work on another system.
photosynthesis - The process in green plants and certain other organisms by which carbohydrates
are synthesized from carbon dioxide and water using light as an energy source. Most forms of
photosynthesis release oxygen as a byproduct.
stimulus - Something causing or regarded as causing a response.
organelle - A differentiated structure within a cell, such as a mitochondrion, vacuole, or
chloroplast, that performs a specific function.
metamorphosis - A change in the form and often habits of an animal during normal development
after the embryonic stage.
adapt - To make suitable to or fit for a specific use or situation.
mutation - The act or process of being altered or changed.
homeostasis - The ability or tendency of an organism or cell to maintain internal equilibrium by
adjusting its physiological processes.
Animal and Plant Cell Organelles:
adenosine triphosphate (ATP) - An adenosine-derived nucleotide that contains high-energy
phosphate bonds and is used to transport energy to cells for biochemical processes, including
muscle contraction and enzymatic metabolism, through its hydrolysis to ADP.
amoeba - Any of various one-celled aquatic or parasitic protozoans of the genus Amoeba or
related genera, having no definite form and consisting of a mass of protoplasm containing one or
more nuclei surrounded by a flexible outer membrane.
cell membrane - The semipermeable membrane that encloses the cytoplasm of a cell. Also called
plasma membrane.
cell wall - The rigid outermost cell layer found in plants and certain algae, bacteria, and fungi but
characteristically absent from animal cells.
centrioles - One of two cylindrical cellular structures that are composed of nine triplet
microtubules and form the asters during mitosis.
chloroplasts - A chlorophyll-containing plastid found in algal and green plant cells.
chlorophyll - Any of a group of green pigments that are found in the chloroplasts of plants and in
other photosynthetic organisms such as cyanobacteria.
chromatin - A complex of nucleic acids and proteins in the cell nucleus that stains readily with
basic dyes and condenses to form chromosomes during cell division.
chromosomes - A threadlike linear strand of DNA and associated proteins in the nucleus of
eukaryotic cells that carries the genes and functions in the transmission of hereditary information.
cytoplasm - The protoplasm outside the nucleus of a cell.
deoxyribonucleic acid (DNA) - A nucleic acid that carries the genetic information in the cell and
is capable of self-replication and synthesis of RNA.
endoplasmic reticulum - A membrane network within the cytoplasm of cells involved in the
synthesis, modification, and transport of cellular materials.
enzymes - Any of numerous proteins or conjugated proteins produced by living organisms and
functioning as biochemical catalysts.
7th Grade Science Content Vocabulary
eukaryotic cells - A single-celled or multicellular organism whose cells contain a distinct
membrane-bound nucleus.
food vacuole - A vacuole in which phagocytized food is digested.
genetic code - The sequence of nucleotides in DNA or RNA that determines the specific amino
acid sequence in the synthesis of proteins. It is the biochemical basis of heredity and nearly
universal in all organisms.
golgi complex - A complex of parallel, flattened saccules, vesicles, and vacuoles that lies adjacent
to the nucleus of a cell and is concerned with the formation of secretions within the cell. Also
called Golgi apparatus.
lysosomes - Single, membrane-bound sacs that contain digestive enzymes.
mitochondria - A spherical or elongated organelle in the cytoplasm of nearly all eukaryotic cells,
containing genetic material and many enzymes important for cell metabolism, including those
responsible for the conversion of food to usable energy.
nuclear - Of, relating to, or forming a nucleus.
nucleus - A large, membrane-bound, usually spherical protoplasmic structure within a living cell,
containing the cell's hereditary material and controlling its metabolism, growth, and reproduction.
nucleolus - A small, typically round granular body composed of protein and RNA in the nucleus
of a cell. It is usually associated with a specific chromosomal site and involved in ribosomal RNA
synthesis and the formation of ribosomes.
organelles - A differentiated structure within a cell, such as a mitochondrion, vacuole, or
chloroplast, that performs a specific function.
plasma membrane - The semipermeable membrane that encloses the cytoplasm of a cell.
prokaryotic cell - any cell that lacks distinct membrane-bound nucleus and organelles in its
cytoplasm, including bacteria and blue-green algae
protein - Any of a group of complex organic macromolecules that contain carbon, hydrogen,
oxygen, nitrogen, and usually sulfur and are composed of one or more chains of amino acids.
ribosome - Small particles, present in large numbers in every living cell, whose function is to
convert stored genetic information into protein molecules.
vacuole - A membrane-bound organelle found in certain protists that pumps fluid in a cyclical
manner from within the cell to the outside by alternately filling and then contracting to release its
contents at various points on the surface of the cell.
Homeostasis:
selectively permeable membrane - Allowing passage of certain, especially small, molecules or
ions but acting as a barrier to others.
passive transport - The movement of a chemical substance across a cell membrane without
expenditure of energy by the cell, as in diffusion.
osmosis - Diffusion of fluid through a semipermeable membrane from a solution with a low solute
concentration to a solution with a higher solute concentration until there is an equal concentration
of fluid on both sides of the membrane.
facilitated transport - The transport of certain materials across a cell membrane, down a
concentration gradient, assisted by enzyme-like carrier proteins embedded in the membrane and
without the explicit provision of energy.
carrier proteins - Membrane proteins that have a high affinity for particular solutes, e.g. glucose,
and which facilitate the passage of these solutes through membrane barriers.
7th Grade Science Content Vocabulary
active transport - The movement of a chemical substance through a gradient of concentration or
electrical potential in the direction opposite to normal diffusion, requiring the expenditure of
energy.
endocytosis - A process of cellular ingestion by which the plasma membrane folds inward to bring
substances into the cell.
exocytosis - A process of cellular secretion or excretion in which substances contained in vesicles
are discharged from the cell by fusion of the vesicular membrane with the outer cell membrane.
isotonic - Describing solutions that have the same osmotic pressure.
hypotonic - Having the lower osmotic pressure of two fluids.
hypertonic - Having the higher osmotic pressure of two solutions.
solute - A substance dissolved in another substance, usually the component of a solution present in
the lesser amount.
solvent - Capable of dissolving another substance.
Hierarchy of Life:
cell theory - A principle that describes the cell as the fundamental unit of all living organisms. A
principle that describes the properties of an organism as the sum of the properties of its component
cells.
cell - The smallest structural unit of an organism that is capable of independent functioning,
consisting of one or more nuclei, cytoplasm, and various organelles, all surrounded by a
semipermeable cell membrane.
tissue - An aggregation of morphologically similar cells and associated intercellular matter acting
together to perform one or more specific functions in the body.
connective tissue - Tissue arising chiefly from the embryonic mesoderm that is characterized by a
highly vascular matrix and includes collagenous, elastic, and reticular fibers, adipose tissue,
cartilage, and bone.
epithelial tissue - A form of stratified epithelium found in the urinary bladder; cells vary between
squamous, when the tissue is stretched, and columnar, when not stretched.
muscle tissue - A tissue composed of fibers capable of contracting to effect bodily movement.
nervous tissue - The nerve cells and neuroglia of the nervous system.
organ - A differentiated part of an organism, such as an eye, wing, or leaf, that performs a specific
function.
organ system - A group of organs in the human body that work together to carry out a vital
body-function.
organism - An individual form of life, such as a plant, animal, bacterium, protist, or fungus; a
body made up of organs, organelles, or other parts that work together to carry on the various
processes of life.
What Cells Need:
nutrients - A source of nourishment, especially a nourishing ingredient in a food.
waste - Excreted from the body.
enzymes - Any of numerous proteins or conjugated proteins produced by living organisms and
functioning as biochemical catalysts.
stomata - A small aperture in the surface of a membrane.
7th Grade Science Content Vocabulary
Digestive and Circulatory Systems:
digestive system - The alimentary canal and digestive glands regarded as an integrated system
responsible for the ingestion, digestion, and absorption of food.
peristalsis - Wavelike muscle movement in alimentary canal that pushes contents along.
esophagus - The muscular membranous tube for the passage of food from the pharynx to the
stomach; the gullet.
stomach - The enlarged, saclike portion of the alimentary canal, one of the principal organs of
digestion, located in vertebrates between the esophagus and the small intestine.
duodenum - The beginning portion of the small intestine, starting at the lower end of the stomach
and extending to the jejunum.
small intestine - The narrow, winding, upper part of the intestine where digestion is completed
and nutrients are absorbed by the blood. It extends from the pylorus to the cecum and consists of
the duodenum, the jejunum, and the ileum.
large intestine - The portion of the intestine that extends from the ileum to the anus, forming an
arch around the convolutions of the small intestine and including the cecum, colon, rectum, and
anal canal.
colon - The section of the large intestine extending from the cecum to the rectum.
liver - A large, reddish-brown, glandular vertebrate organ located in the upper right portion of the
abdominal cavity that secretes bile and is active in the formation of certain blood proteins and in
the metabolism of carbohydrates, fats, and proteins.
pancreas - A long, irregularly shaped gland in vertebrates, lying behind the stomach, that secretes
pancreatic juice into the duodenum and insulin, glucagon, and somatostatin into the bloodstream.
gall bladder - A small, pear-shaped muscular sac, located under the right lobe of the liver, in
which bile secreted by the liver is stored until needed by the body for digestion.
salivary gland - A gland that secretes saliva, especially any of three pairs of large glands, the
parotid, submaxillary, and sublingual, whose secretions enter the mouth and mingle in saliva.
circulatory system - The bodily system consisting of the heart, blood vessels, and blood that
circulates blood throughout the body, delivers nutrients and other essential materials to cells, and
removes waste products.
specialized cells - A cell that performs a specific function, as in the case of a liver cell, a blood cell,
or a neuron.
white blood cells - Any of various blood cells that have a nucleus and cytoplasm, separate into a
thin white layer when whole blood is centrifuged, and help protect the body from infection and
disease. White blood cells include neutrophils, eosinophils, basophils, lymphocytes, and
monocytes.
platelets - A minute, non-nucleated, disk-like cytoplasmic body found in the blood plasma of
mammals that is derived from a megakaryocyte and functions to promote blood clotting.
atrium - A body cavity or chamber, especially either of the upper chambers of the heart that
receives blood from the veins and forces it into a ventricle.
ventricle - A small cavity or chamber within a body or organ, especially: The chamber on the left
side of the heart that receives arterial blood from the left atrium and contracts to force it into the
aorta and the chamber on the right side of the heart that receives venous blood from the right
atrium and forces it into the pulmonary artery.
plasma - The clear, yellowish fluid portion of blood, lymph, or intramuscular fluid in which cells
are suspended. It differs from serum in that it contains fibrin and other soluble clotting elements.
7th Grade Science Content Vocabulary
capillaries - The tiny blood vessels throughout the body that connect arteries and veins.
arteries - any of the muscular elastic tubes that form a branching system and that carry blood away
from the heart to the cells, tissues, and organs of the body.
veins - Any of the membranous tubes that form a branching system and carry blood to the heart.
anemia - A pathological deficiency in the oxygen-carrying component of the blood, measured in
unit volume concentrations of hemoglobin, red blood cell volume, or red blood cell number.
leukemia - Any of various acute or chronic neoplastic diseases of the bone marrow in which
unrestrained proliferation of white blood cells occurs, usually accompanied by anemia, impaired
blood clotting, and enlargement of the lymph nodes, liver, and spleen.
hypertension - Arterial disease in which chronic high blood pressure is the primary symptom.
Reproduction:
sexual - Relating to, produced by, or involving reproduction characterized by the union of male
and female gametes: sexual reproduction.
asexual - Relating to, produced by, or involving reproduction that occurs without the union of
male and female gametes, as in binary fission or budding.
fertilization - The union of male and female gametes to form a zygote.
ovary - The usually paired female or hermaphroditic reproductive organ that produces ova and, in
vertebrates, estrogen and progesterone.
ovum (egg) - The female reproductive cell or gamete of animals.
sperm - A male gamete or reproductive cell.
testes - Male reproductive organs.
scrotum - The external sac of skin enclosing the testes in most mammals.
urethra - The canal through which urine is discharged from the bladder in most mammals and
through which semen is discharged in the male.
uterus - A hollow muscular organ located in the pelvic cavity of female mammals in which the
fertilized egg implants and develops.
vagina - he passage leading from the opening of the vulva to the cervix of the uterus in female
mammals.nstruation - The process or an instance of discharging the menses.
follicle - the ovum and its encasing cells, at any stage of its development.
puberty - The stage of adolescence in which an individual becomes physiologically capable of
sexual reproduction.
menopause - The permanent cessation of menstruation, occurring usually between the ages of 45
and 55.
implantation - The process by which a fertilized egg implants in the uterine lining.
fetus - The unborn young of a viviparous vertebrate having a basic structural resemblance to the
adult animal.
fission - An asexual reproductive process in which a unicellular organism divides into two or more
independently maturing daughter cells.
fragmentation - Division into small pieces.
parthenogenesis - A form of reproduction in which an unfertilized egg develops into a new
individual, occurring commonly among insects and certain other arthropods.
vegetative propagation - Production of a new plant from a portion of another plant, such as a stem
or branch.
budding - Being in an early developmental stage.
7th Grade Science Content Vocabulary
penis - The male organ of copulation in higher vertebrates, homologous with the clitoris. In
mammals, it also serves as the male organ of urinary excretion.
vas deferens - The main duct through which semen is carried from the epididymis to the
ejaculatory duct.
zygote - The cell formed by the union of two gametes, especially a fertilized ovum before
cleavage.
fallopian tube - Either of a pair of slender ducts through which ova pass from the ovaries to the
uterus in the female reproductive system of humans and higher mammals.
Nervous System:
neuron - Any of the impulse-conducting cells that constitute the brain, spinal column, and nerves,
consisting of a nucleated cell body with one or more dendrites and a single axon. Also called nerve
cell.
neurotransmitter - A chemical substance, such as acetylcholine or dopamine, that transmits
nerve impulses across a synapse.
central nervous system - The portion of the vertebrate nervous system consisting of the brain and
spinal cord.
peripheral nervous system - The part of the vertebrate nervous system constituting the nerves
outside the central nervous system and including the cranial nerves, spinal nerves, and sympathetic
and parasympathetic nervous systems.
somatic nervous system - The portion of the nervous system concerned with the control of
voluntary muscle and relating the organism with its environment.
autonomic nervous system - The part of the vertebrate nervous system that regulates involuntary
action, as of the intestines, heart, and glands, and that is divided into the sympathetic nervous
system and the parasympathetic nervous system.
sensory division - Transmits impulses from sense organs to the central nervous system.
motor division - Transmits impulses from the central nervous system to the muscles or glands.
Excretory and Respiratory System:
kidney - Either one of a pair of organs in the dorsal region of the vertebrate abdominal cavity,
functioning to maintain proper water and electrolyte balance, regulate acid-base concentration,
and filter the blood of metabolic wastes, which are then excreted as urine.
nephron - Any of the numerous filtering units of the vertebrate kidney that remove waste matter
from the blood.
Bowman’s capsule - A double-walled, cup-shaped structure around the glomerulus of each
nephron of the vertebrate kidney. It serves as a filter to remove organic wastes, excess inorganic
salts, and water.
ureter - The long, narrow duct that conveys urine from the kidney to the urinary bladder or cloaca.
urinary bladder - An elastic, muscular sac situated in the anterior part of the pelvic cavity in
which urine collects before excretion.
gills - The respiratory organ of most aquatic animals that breathe water to obtain oxygen,
consisting of a filamentous structure of vascular membranes across which dissolved gases are
exchanged.
spiracles - Any of several tracheal openings in the exoskeleton of an insect or a spider.
carbon dioxide - A colorless, odorless, incombustible gas, CO2, formed during respiration.
7th Grade Science Content Vocabulary
mucus - The viscous, slippery substance that consists chiefly of mucin, water, cells, and inorganic
salts and is secreted as a protective lubricant coating by cells and glands of the mucous
membranes.
cilia - Relatively short, centriole-based, hairlike processes on certain anatomical cells and motile
organisms.
trachea - A thin-walled, cartilaginous tube descending from the larynx to the bronchi and carrying
air to the lungs. Also called windpipe.
epiglottis - The thin elastic cartilaginous structure located at the root of the tongue that folds over
the glottis to prevent food and liquid from entering the trachea during the act of swallowing.
larynx - The part of the respiratory tract between the pharynx and the trachea, having walls of
cartilage and muscle and containing the vocal cords enveloped in folds of mucous membrane.
bronchial tube - A bronchus or any of its branches.
alveoli - A tiny, thin-walled, capillary-rich sac in the lungs where the exchange of oxygen and
carbon dioxide takes place. Also called air sac.
diaphragm - A muscular membranous partition separating the abdominal and thoracic cavities
and functioning in respiration.
Immunity, Endocrine, Lymphatic, Muscular, and Skeletal Systems:
immune system - The integrated body system of organs, tissues, cells, and cell products such as
antibodies that differentiates self from non-self and neutralizes potentially pathogenic organisms
or substances.
integumentary system - The bodily system consisting of the skin and its associated structures,
such as the hair, nails, sweat glands, and sebaceous glands.
epidermis - The outer, protective, nonvascular layer of the skin of vertebrates, covering the
dermis.
dermis - The sensitive connective tissue layer of the skin located below the epidermis, containing
nerve endings, sweat and sebaceous glands, and blood and lymph vessels.
inflammatory response - A nonspecific defensive reaction of the body to invasion by a foreign
substance or organism that involves phagocytosis by white blood cells and is often accompanied
by accumulation of pus and an increase in the local temperature.
phagocyte - A cell, such as a white blood cell, that engulfs and absorbs waste material, harmful
microorganisms, or other foreign bodies in the bloodstream and tissues.
active immunity - Immunity resulting from the development of antibodies in response to the
presence of an antigen, as from vaccination or exposure to an infectious disease.
passive immunity - Immunity acquired by the transfer of antibodies from another individual, as
through injection or placental transfer to a fetus.
lymphatic system - The interconnected system of spaces and vessels between body tissues and
organs by which lymph circulates throughout the body.
lymph nodes - Any of the small bodies located along the lymphatic vessels, particularly at the
neck, armpit, and groin, that filter bacteria and foreign particles from lymph fluid. During
infection, lymph nodes may become swollen with activated lymphocytes.
endocrine system - The bodily system that consists of the endocrine glands and functions to
regulate body activities.
glands - A cell, a group of cells, or an organ that produces a secretion for use elsewhere in the body
or in a body cavity or for elimination from the body.
7th Grade Science Content Vocabulary
smooth muscle - Muscle tissue that contracts without conscious control, having the form of thin
layers or sheets made up of spindle-shaped, unstriated cells with single nuclei and found in the
walls of the internal organs, such as the stomach, intestine, bladder, and blood vessels, excluding
the heart.
skeletal muscle - A usually voluntary muscle made up of elongated, multi-nucleated, transversely
striated muscle fibers, having principally bony attachments. Also called striated muscle.
cardiac muscle - The specialized striated muscle tissue of the heart; the myocardium.
tendon - A band of tough, inelastic fibrous tissue that connects a muscle with its bony attachment.
ligament - A sheet or band of tough, fibrous tissue connecting bones or cartilages at a joint or
supporting an organ.
red bone marrow - The blood-forming tissue found within the internal cavities of bone.
yellow bone marrow - The fatty tissue that occupies the internal cavities of long bones and begins
to replace red bone marrow soon after birth.
ball & socket joint - a joint in which the distal bone is capable of motion around an indefinite
number of axes, which have one common center.
hinge joint - A joint, such as the elbow, in which a convex part of one bone fits into a concave part
of another, allowing motion in only one plane.