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26.18: S

Difficulty Level: At Grade Created by: CK-12
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decomposer such as a fungus or protozoan that feeds on any remaining organic matter that is left after other decomposers do their work
saturated fatty acid
molecule in lipids in which carbon atoms are bonded to as many hydrogen atoms as possible
type of early amniote that evolved during the Carboniferous Period and eventually gave rise to dinosaurs, reptiles, and birds
decomposer that consumers the soft tissues of dead animals
distinctive way of gaining knowledge about the natural world that tries to answer questions with evidence and logic
scientific investigation
plan for asking questions and testing possible answers
scientific law
statement describing what always happens under certain conditions in nature
scientific method
the process of a scientific investigation
scientific theory
broad explanation that is widely accepted as true because it is supported by a great deal of evidence
sebaceous gland
gland in the dermis of skin that produces sebum, an oily substance that waterproofs the skin and hair
secondary succession
change in the numbers and types of species that live in a community that occurs in an area that was previously colonized but has been disturbed
structure produced by a seed plant that contains an embryo and food supply enclosed within a tough coat
seed coat
tough covering of a seed that protects the embryo and keeps it from drying out until conditions are favorable for germination
division of an animal body into multiple segments
fluid containing sperm and gland secretions that nourish sperm and carry them through the urethra and out of the body
sensory neuron
type of neuron that carries nerve impulses from tissue and organs to the spinal cord and brain
sensory receptor
specialized nerve cell that responds to a particular type of stimulus such as light or chemicals
part of a flower that helps protect it while it is still in bud
of or relating to an animal that is unable to move from place to place
sex chromosome
X or Y chromosome (in humans)
sex hormone
chemical messenger that controls sexual development and reproduction
sex-linked gene
gene located on a sex chromosome
sex-linked trait
traits controlled by a gene located on a sex chromosome
sexual dimorphism
differences between the phenotypes of males and females of the same species
sexually transmitted infection (STI)
infection caused by a pathogen that spreads mainly through sexual contact; also known as sexually transmitted disease (STD)
sexual reproduction
type of reproduction that involves the fertilization of gametes produced by two parents and produces genetically variable offspring
sixth mass extinction
current mass extinction caused primarily by habitat loss due to human actions
skeletal muscle
voluntary, striated muscle that is attached to bones of the skeleton and helps the body move
skeletal system
human body system that consists of all the bones of the body as well as cartilage and ligaments
sliding filament theory
theory that explains muscle contraction by the sliding of myosin filaments over actin filaments within muscle fibers
slime mold
fungus-like protist commonly found on rotting logs and other decaying organic matter
small intestine
long, narrow, tube-like organ of the digestive system where most chemical digestion of food and virtually all absorption of nutrients take place
smooth muscle
involuntary, nonstriated muscle that is found in the walls of internal organs such as the stomach
social animal
animal that lives in a society
close-knit group of animals of the same species that live and work together
sodium-potassium pump
type of active transport in which sodium ions are pumped out of the cell and potassium ions are pumped into the cell with the help of a carrier protein and energy from ATP
mixture of eroded rock, minerals, organic matter, and other materials that is essential for plant growth and forms the foundation of terrestrial ecosystems
mixture that has the same composition throughout
somatic mutation
mutation that occurs in cells of the body other than gametes
somatic nervous system (SNS)
division of the peripheral nervous system that controls voluntary, conscious activities and reflexes
depositing large numbers of gametes in the same place and at the same time by fish or amphibians
evolution of different adaptations in competing species, which allows them to live in the same area without competing
process by which a new species evolves
group of organisms that are similar enough to mate together and produce fertile offspring
male gamete
process of producing sperm in the testes
type of plant that reproduces by producing seeds
spinal cord
thin, tubular bundle of nervous tissue that extends from the brainstem down the back to the pelvis and connects the brain with the peripheral nervous system
spongy bone
light, porous inner layer of bone that contains bone marrow
sporangium (plural, sporangia)
structure on a plant of the sporophyte generation that produces spores for asexual reproduction
diploid generation in the life cycle of a plant that results from sexual reproduction with gametes and that produces spores for asexual reproduction
sporozoa (singular, sporozoan)
type of protozoa that cannot move as adults
stabilizing selection
type of natural selection for a polygenic trait in which phenotypes at both extremes of the phenotypic distribution are selected against, resulting in a narrowing of the range of phenotypic variation
male reproductive structure of a flower that consists of a stalk-like filament and a pollen-producing anther
something that triggers a behavior
sac-like organ of the digestive system between the esophagus and small intestine in which both mechanical and chemical digestion take place
stomata (singular, stoma)
tiny pore in the epidermis of a plant leaf that controls transpiration and gas exchange with the air
space outside the thylakoid membranes of a chloroplast where the Calvin cycle of photosynthesis takes place
process in which ice and snow change directly to water vapor
survivorship curve
graph that represents the individuals still alive at each age in a population
sustainable use
use of resources in a way that meets the needs of the present and also preserves the resources for the use of future generations
sweat gland
gland in the dermis of skin that produces the salty fluid called sweat, which excretes wastes and helps cool the body
swim bladder
balloon-like internal organ in most fish that can be used to move up or down through the water column by changing the amount of gas it contains
close relationship between organisms of different species in which at least one of the organisms benefits from the relationship
sympatric speciation
evolution of a new species that occurs when without geographic separation first occurring between members of an original species
place where an axon terminal meets another cell
type of early amniote that evolved during the Carboniferous Period and eventually gave rise to mammals
synthetic biology
field of biology involved in engineering new functions from living systems
sexually transmitted infection caused by bacteria that may eventually be fatal if untreated
systemic circulation
part of the circulatory system that carries blood between the heart and body

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Date Created:
Feb 23, 2012
Last Modified:
Sep 13, 2016
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