REFERENCE SECTION: BIOLOGICAL TERMS
Complete the Table below, which defines or describes some important
biological terms that are occasionally included in chemistry texts, by
inserting the correct word from this list: Active transport; Allele; 
Autotroph; Cell; Diffusion; Codominance; Dominant allele; Enzyme; 
Excretion; Food chain; Gene; Genotype; Growth; Herbivores &; Carnivores; 
Heterotroph; Heterozygous; Homeostasis; Homozygous; Irritability; 
Limiting factor; Movement; Nutrition; Organism; Osmosis; Phenotype; 
Population; Recessive allele; Reproduction; Respiration; Saprotrophs; 
Sex-linked allele; Species; Trophic level.
 Term     
             Definition or Description
 Organism
 A structure containing the genetic code for
 reproduction.
 Species
 A group of organisms capable of breeding to produce
 fertile offspring; e.g., Ursos arctos (brown bear).
 Population
 A group of individuals in a species that live in a
 defined habitat.
 Cell
 An assembly of fragile molecules, enclosed within a
 semi-permeable membrane, which show some or all the
 other characteristics of living things.  *
 Homeostasis 
 The maintenance of a constant internal environment
 despite changes in the external environment.
 Excretion
 The removal of waste products of cellular metabolism. 
 Movement
 The change in position of whole or part of a living
 organism.
 Respiration
 The enzyme-controlled release of energy, in the form
 of ATP, by the oxidation of organic compounds.
 Reproduction 
 The formation of new organisms to ensure the survival
 of the species.
 Irritability
 The ability to detect and respond to changes in the
 external environment.
 Nutrition
 The processes by which chemical energy is obtained
 and assimilated.
 Growth
 The irreversible increase in dry mass of an organism
 via biosynthesis and mitotic cell division.
 Enzyme
 A catalytic protein.
 Diffusion
 The net movement of particles down the concentration
 gradient; i.e., from high to low concentration.
 Active
 transport
 The net movement of solute particles, across a
 semi-permeable membrane, against the concentration
 gradient; i.e., from low to high concentration.
 Osmosis
 The net movement of water particles, across a semi-
 permeable membrane, down the concentration gradient; 
 i.e., from high  to low concentration.


 Term     
             Definition or Description
 Autotroph
 An organism which biosynthesizes its chemical energy
 from inorganic compounds.
 Heterotroph
 An organism which obtains its chemical energy from
 the organic compounds produced by other organisms.
 Herbivores &
 Carnivores
 Ingestive heterotrophs which obtain their chemical
 energy from living organisms.
 Saprotrophs
 Absorptive heterotrophs which obtain their chemical
 energy from dead organisms and their excretions.
 Food chain
 A series of organisms through which chemical energy
 is transferred by feeding.  #
 Trophic level
 The position of an organism in a food pyramid.
 Limiting
 factor
 Any variable which reduces the rate of a biological
 process from its possible maximum.
 Gene
 The basic unit of inheritance; in molecular terms,
 it is the sequence of DNA nucleotides which codes for 
 the synthesis of one polypeptide.  $
 Allele
 One of a number of alternative forms of a gene.
 Genotype
 The allele(s) present for a specific characteristic.
 Phenotype
 The physical or chemical expression of the genotype.
 Dominant
 allele
 One allele of a pair which has an effect on the
 phenotype when homozygous or heterozygous. (Shown in
 a genetic diagram by a capital letter; e.g., H.)
 Recessive
 allele
 One allele of a pair which has an effect on the
 phenotype when homozygous. (Shown in a genetic 
 diagram by a small letter; e.g., h.)
 Codominance
 When both alleles in a heterozygous individual are
 expressed in the organism's phenotype.
 Sex-linked
 allele
 An alternative form of a gene which is carried on a
 sex chromsome.
 Homozygous
 Where two alleles for a characteristic are the same
 (e.g., HH or hh).
 Heterozygous
 Where two alleles for a characteristic are different
 (e.g., Hh).
                                                                   [33]
*  Most living organisms usually show nine characteristics; i.e.,
cellular organization, homeostasis, excretion, movement, respiration, 
reproduction, irritability, nutrition, and growth. (... 'Chemrring' ?).
[Viruses, which are invariably parasitic and pathogenic, are viewed as
non-living organisms because they do not show these characteristics.]
#  A similar transfer occurs in a food web, but involves interacting
organisms (i.e., communities).
§  Despite their surprisingly frequent appearances, the terms 'dominant 
gene' and 'recessive gene' are both incorrect.

Dr. R. Peters Next Contents' List & Teacher's Notes