THE FACTORS WHICH DETERMINE AN
ORGANISM’S PHENOTYPE
PROKARYOTES
Cell Biology
Gas Exchange &
Transport
Cell
Biology
PROTOCTISTS FUNGI
Biochemistry
Physiology
Nutrition
Homeostasis &
Excretion
Biochemistry
Enzymes coded for by genes
determine chemical
reactions which affect how
an organism looks e.g.
pigments
Physiology
PLANTS
Genes & Genetics
Coordination &
Movement
Genes &
Genetics
determined by
genes inherited
genes& adapted by
from parents via
natural selection -this meiosis
affects phenotype
genes contribute
exchange surface
to 'genotype' &
limits size
so affect
transport of gases
phenotype
limits size + shape
ANIMALS
Ecology
Reproduction &
Growth
Ecology
Environment
affects phenotype
e.g. size of limpets
Intro: phenotype=characteristics of organism we see or detect
=affected by (1) genotype
(2) environment, & their interactions with one another.
=e.g. height, eye colour, ABO blood group, presence or absence of cystic
fibrosis.
Para 1: Enzymes coded for by genes determine chemical reactions which affect how an organism looks
or works e.g. pigments. Lung protein in cystic fibrosis.
Para 2: genes inherited from parents via meiosis, contribute to genotype & so affect phenotype.
Para 3: Interaction of genes e.g. blood groups
Para4: Environmental effects: as organism adapts to suit environment better, via natural selection,
phenotype (size & shape) changes. E.g. limpets Hence effect of environment.
Para 5: food source available in environment affects phenotype, e.g. protein needed for tissue &
cell growth, so more protein available, more probably taken up by organism, greater
growth. Link this to digestive enzymes organism has (dependent on genes), this limits
ability to use nutrients & so affects efficiency & growth.
Conc: summary of environmental factors & genotype effect on phenotype. Importance of lots
combinations of genes as expressed in phenotype-variation-population more likely to
survive disease etc..