SCALE: The difference between each number on the axis of a graph.
SCAVENGER: An animal that feeds on animals that have already died. Example: vultures
SCHLEIDEN, Matthias: The scientist who said all plants are made of cells.
SCHWANN, Theodor: The scientist who said all animals are made of cells.
SCIENTIFIC METHOD: Scientists use the following steps to solve a problem :
1) State a problem or observation
2) Make a hypothesis
3) Perform a controlled experiment
4) Draw conclusions or make a theory
1) State a problem or observation
2) Make a hypothesis
3) Perform a controlled experiment
4) Draw conclusions or make a theory
SECONDARY SUCCESSION: A sequence of changes that take place after a community is disrupted by natural disasters or human actions.
SEDIMENTARY ROCK: A type of rock formed near the surface when pieces of gravel, sand, or others rocks become stuck together. Examples of sedimentary rocks are conglomerate and sandstone. This is the only type of rock in which fossils are found.
SELECTIVE PERMEABILITY: Only allowing certain things to enter and exit. The cell membrane is selectively permeable.
SESSILE: An organism that is permanently attached to a surface.
SEX CELLS: Haploid gametes that are made during meiosis. Females produces sex cells called ovum or eggs. Males produce sex cells called sperm.
SEX CHROMOSOME: The 23rd pair of chromosomes that determine the sex of an individual. XX = female, XY = male
SEX-LINKED TRAITS: Traits controlled by genes located on the 23rd pair of chromosomes (sex chromosomes)
SEXUAL REPRODUCTION: The process of reproduction that requires a male and female gamete (sperm and egg).
SISTER CHROMATIDS: The two identical halves of a chromosome that are held together by the centromere.
SOMATIC CELL: Cells that are diploid and are created by mitosis. These cells are also called body cells. All cells that are NOT used for sexual reproduction are called somatic cells.
SPECIATION: The process of evolution that gives rise to a new species.
SPECIES: A group of organisms that can produce fertile offspring (babies).
SPECIFIC HEAT: A property of matter that refers to how much energy is needed to raise the temperature of substance. Water has a very high specific heat, so it does not get very hot or very cold easily.
SPERM: A male, haploid gamete (sex cell) used for sexual reproduction. Sperm are created by the process of meiosis.
SPONTANEOUS GENERATION: A mistaken idea that life can arise from nonliving materials. This was disproven by Francesco Redi.
SUCCESSION: A pattern of changes in species composition in an area. Maybe after a disturbance (secondary succession), or in a place where there has been no soil or previous life (primary succession).
SUGAR: See carbohydrate
SUPERPOSITION: The law of superposition states that in undisturbed layers of rock, the oldest rocks are at the bottom. Each rock layer is younger than the rock layer below it, and older than the rock layer above it.
SURFACE TENSION: A property of water that refers to water's ability to form a thin layer on the surface of ponds and lakes that insects can walk on.
SYMBIOSIS: Two organisms living together and somehow interacting. Examples include mutualism, commensalism, and parasitism.
SYMMETRY: A term that describes the arrangement of body structures.