Biology Midterm

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Hypothesis

a tentative scientific explanation that can be tested by further observation or experimentation

Control Group

an experiment in which only one variable is changed

Independent variable

the variable deliberately changed

Controlled Experiment

an experiment in which only one variable is changed

Qualitative Data

data that is descriptive and involves characteristics that cannot be measured

Inference

a logical interpretation based on what scientists already know

Quantitative Data

numbers obtained by counting or measuring

Theory

a tested, highly-reliable scientific explanation of events in the natural world

Observation

the act of noticing and describing events or processes in a careful, orderly way

Dependent Variable

the variable that is observed or measured by the scientist

Sexual Reproduction

cells from two different parents unite to produce the first cell of a new organism

Asexual Reproduction

a single parent gives rise to a new organism

DNA

the universal genetic material that is composed of nucleotides

Metabolism

combination of chemical reactions that an organism uses for its life processes

Stimulus

a signal to which an organism responds

Homeostasis

relatively constant set of conditions that an organism maintains

Evolve

change over time at the population level

Growth

enlargement in size

Development

a single fertilized egg cell divides again and again to produce the many cells of a mature organism

Cell

basic structure of life; smallest unit of life

Genus

a group of similar species; first name in a scientific name

Domain

The most inclusive category in modern classification systems; there are three of these (e.g. Eukarya or Archaea)

Taxon

groups used to classify organisms (e.g. class, order, phylum, species, kingdom, etc.)

Clade

a group of species that includes a single common ancestor and all of its descendants

Common ancestor

a hypothetical organism that lived in the past and gave rise to two different lineages

Cladogram

a tree-like diagram that shows evolutionary relationships between different species

Binomial nomenclature

a system of naming species using a two-part scientific name

Taxonomy

a system of naming and classifying organisms based on shared characteristics

Derived character

a trait that arose in the most recent common ancestor of a lineage and was passed to its descendants

Species

the most specific taxon; a group of individuals that live naturally together and successfully interbreed

Linnaean classification

a hierarchical system of biological classification first used in the 1700s

Kingdom

the largest category in traditional Linnaean classification; there are six of these (e.g. Protista or Animalia)

Dichotomous key

a classification tool that uses a system of paired statements to identify an organism

Prokaryote

a single-celled organism without a nucleus or membrane-bound organelles

Eukaryote

type of cell that has a nucleus and membrane-bound organelles

Autotroph

an organism that can obtain energy and raw materials from inorganic sources; a producer

Heterotroph

an organism that must obtain energy and raw materials by eating other organisms; a consumer

Archaea

domain with organisms that are prokaryotic, such as methanogens and halophiles

Bacteria

domain with organisms that are unicellular, prokaryotes such as E. coli and S. pneumoniae

Eukarya

domain that includes organisms with eukaryotic cells

Protista

kingdom with a wide-range of organisms that don't fit in any other categories

Fungi

kingdom with organisms that are heterotrophic, eukaryotes with cell membranes made of chitin

Animalia

kingdom with organisms that are heterotrophic, eukaryotes without cell walls

Plantae

kingdom with organisms that are almost all multicellular, autotrophic, eukaryotes

Eubacteria

kingdom with prokaryotes that do not live in harsh environments

Archaebacteria

kingdom with organisms that are prokaryotes that live in harsh environments

Speciation

The process of forming two species from one ancestral species

Temporal isolation

A form of reproductive isolation in which species mate during different times

Geographic isolation

A form of reproductive isolation in which species are separated in location

Behavioral isolation

A form of reproductive isolation in which species have different mating rituals

Postzygotic isolation

A form of reproductive isolation in which species can mate but can't produce fertile offspring

Natural selection

A process by which organisms that are most suited to their environment survive and reproduce

Artificial selection

The process used by humans to choose animals and plants that have desirable traits

Biogeography

Study of the past and present distribution of organisms across the globe

Convergent evolution

A process that results in analogous structures, or similarities due to environment rather than shared ancestry

Biological fitness

How well an organism survives and reproduces in its environment; the ability to get its genes into the next generation

Homologous structures

Structures that are shared as the result of a common ancestry

Analogous structures

Structures that are shared because of similar environment rather than common ancestry

Enzyme

A type of protein that speeds up a chemical reaction in a living thing

Activation energy

the minimum amount of energy required to start a chemical reaction

Substrate

A specific reactant acted upon by an enzyme

Active site

The part of the enzyme where the substrate binds

Monomer

A simple compound whose molecules can join together to form polymers

Polymer

A long molecule consisting of many similar or identical monomers linked together

Dehydration synthesis

A chemical reaction in which two molecules are bonded together with the removal of a water molecule.

Hydrolysis

Breaking down complex molecules by the chemical addition of water

Carbohydrate

compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body

Monosaccharide

A single sugar molecule such as glucose or fructose, the simplest type of sugar.

Polysaccharide

large macromolecule formed from monosaccharides

Lipid

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen.

Triglyceride

a lipid made of three fatty acid molecules and one glycerol molecule

Phospholipid

a lipid containing a phosphate group in its molecule; the structural compound in cell membranes

Saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds

Unsaturated fatty acid

A fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail

Trans fat

An unsaturated fat containing one or more trans double bonds.

Nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

Nitrogenous base

An organic base that contains nitrogen, such as a purine or pyrimidine; a subunit of a nucleotide in DNA and RNA

Nucleic acid (DNA/RNA)

Macromolecules that make up DNA and RNA. Contain the organism's genetic information for making proteins.

Amino acid

compound with an amino group on one end and a carboxyl group on the other end

Polypeptide

long chain of amino acids that makes proteins

Protein

A three dimensional polymer made of monomers of amino acids.

Primary structure

The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain

Tertiary structure

The third level of protein structure; the overall, three-dimensional shape of a polypeptide

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Nucleus

Control center of the cell; only found in eukaryotic cells

Organelles

A tiny cell structure that carries out a specific function within the cell

Nucleolus

Produces and assembles ribosomes in Prokaryotic cells

Ribosomes

transfers and stores DNA

Rough endoplasmic reticulum

Produces proteins in eukaryotic cells

Smooth Endoplasmic Reticulum

produces lipids and steroids in eukaryotic cells

Golgi apparatus

Intracellular transport in eukaryotic cells

Vacuoles and Vesicles

storage and transport

Molecular transport

Small molecules and ions are carried across membranes by proteins in the membrane that act like pumps; Against gradient

Bulk transport

The process by which large particles and macromolecules are transported through the cell membrane (the membrane breaks off and surrounds the particle)

Lysosomes

An organelle containing digestive enzymes

Cytoskeleton

protein filaments that provide shape and aid in movement

Chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

Mitochondria

Produces energy for the cell; powerhouse of the cell

Cell Wall

A rigid layer of nonliving material that surrounds the cells of plants and some other organisms.

Cell Membrane

A cell structure that controls which substances can enter or leave the cell.