Biology EOC

ecology

scientific study of interactions among organisms and between organisms and their environment

biosphere

part of Earth in which life exists including land, water, and air or atmosphere

species

group of similar organisms that can breed and produce fertile offspring

population

group of individuals of the same species that live in the same area

community

assemblages of different populations that live together in a defined area

ecosystem

collection of all the organisms that live in a particular place, together with their nonliving environment

biome

group of ecosystems that have the same climate and dominant communities

autotroph

organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer

producer

organism that can capture energy from sunlight or chemicals and use it to produce food from inorganic compounds; also called an autotroph

photosynthesis

process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches

heterotroph

organism that obtains energy from the foods it consumes; also called a consumer

consumer

organism that relies on other organisms for its energy and food supply; also called a heterotroph

herbivore

organism that obtains energy by eating only plants

carnivore

organism that obtains energy by eating animals

omnivore

organism that obtains energy by eating both plants and animals

decomposer

organism that breaks down and obtains energy from dead organic matter

food chain

series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

food web

network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem

trophic level

step in a food chain or food web

ecological pyramid

diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web

biomass

total amount of living tissue within a given trophic level

food vacuole

small cavity in the cytoplasm of protists that temporarily stores food

cilia

short hairlike projection similar to a flagellum; produces movement in many cells

contractile vacuole

Cavity in the cytoplasm of some protists that collects water and discharges it from the cell

prokaryote

unicellular organism lacking a nucleus

single-gene trait

trait controlled by a single gene that has two alleles

genetic drift

random change in allele frequencies that occurs in small populations

evolution

change in a kind of organism over time; process by which modern organisms have descended from ancient organisms

theory

well-tested explanation that unifies a broad range of observations

adaptation

inherited characteristic that increases an organism's chance of survival

survival of the fittest

process by which the individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection

natural selection

process by which the individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest

nucleotide

building block of a nucleic acid (DNA and RNA)

base pairing

Adenine+ Thymine, Cytosine+ Guanine

chromatin

long strands of DNA found in the eukaryotic cell nucleus; condense to form chromosomes

histone

protein molecule around which DNA is tightly coiled in chromatin

replication

(genetics) the process whereby DNA makes a copy of itself before cell division

DNA polymerase

enzyme that makes bonds between nucleotides, forming an identical strand of DNA during replication

gene

sequence of DNA that codes for a protein and thus determines a trait

mRNA (messenger RNA)

RNA molecule that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell

rRNA (ribosomal RNA)

type of RNA that makes up the major part of ribosomes

tRNA (transfer RNA)

type of RNA molecule that transfers amino acids to ribosomes during protein synthesis

transcription

process in which part of the nucleotide sequence of DNA is copied into a complementary sequence in RNA

RNA polymerase

enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription

codon

three-nucleotide sequence on messenger RNA that codes for a single amino acid

translation

decoding of a mRNA message into a polypeptide chain

anticodon

group of three bases on a tRNA molecule that are complementary to an mRNA codon

mutation

a change or alteration in form or qualities

polyploidy

condition in which an organism has extra sets of chromosomes

sex-linked genes

genes found on the chromosomes that determine sex, XX= female, XY= male

nondisjunction

occurs in meiosis when homologous chromosomes fail to separate

homologous

term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent

diploid

term used to refer to a cell that contains both sets of homologous chromosomes

haploid

term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes

meiosis

process by which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

tetrad

structure containing 4 chromatids that forms during meiosis

crossing-over

process in which homologous chromosomes exchange portions of their chromatids during meiosis

cell division

process by which a cell divides into two new daughter cells

mitosis

part of eukaryotic cell division during which the cell nucleus divides

cytokinesis

division of the cytoplasm during cell division

chromatid

one of two identical "sister" parts of a duplicated chromosome

centromere

area where the chromatids of a chromosome are attached

interphase

period of the cell cycle between cell divisions

cell cycle

series of events that cells go through as they grow and divide

prophase

first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus

centriole

one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope

spindle

fanlike microtubule structure that helps separate the chromosomes during mitosis

metaphase

second phase of mitosis, during which the chromosomes line up across the center of the cell

anaphase

the third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles

telophase

fourth and final phase of mitosis, during which the chromosomes begin to disperse into a tangle of dense material

cancer

disorder in which some of the body's own cells lose the ability to control growth

homologous

term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent

diploid

term used to refer to a cell that contains both sets of homologous chromosomes

haploid

term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes

meiosis

process by which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

tetrad

structure containing 4 chromatids that forms during meiosis

crossing-over

process in which homologous chromosomes exchange portions of their chromatids during meiosis