1. BIOLOGY FORM 5

3. UNDERSTANDING
VARIATION
IN ORGANISMS

4. LEARNING OUTCOMES
 To s tate th e im p ortance of variation in
organis m s .
 To give e xam p le s of variation in h u m ans
 To s tate th e typ e s of variation
 To com p are continu ou s & d is continu ou s
variation.

5. VARIATION IN
ORGANISMS
 VARIATION : the differences
which exist between living
organisms as a result of their
genotypes &/@ the environment.
 To withstand harsh environmental
conditions.
 Examples : height, weight, blood
group, tongue rolling, eye colour
& sex.

6. TYPES OF VARIATION
 T o t : cont
w ypes inuous &discont
inuous v r t
aiaion.
 Continuous v ariation :
– Differ ae sl . Det mined byma genes &/ env onment l
ences r ight er ny @ ir a
influence.
– Bel- ped nor ldistibut cur e.
lsha ma r ion v
– E mpl : height&w .
xa es eight

8.  Dis continuous variation :
– T differ ae discr e (sepaae)&cl rcut
he ences r et rt ea- .
Det mined bydiffer al es ofone, t o @ onl afew
er ent lel w y
genes.
– Notinfl
uenced byenv onment lfa or
ir a ct s.
– E mpl : bl gr gender t
xa es ood oup, , ongue r l &ea l
oling r obe
t
ype.

10. Observe the colour of the hair and
colour of the iris…

12. C OMPARE &
C O N TR A S T
CONTINUOUS DISCONTINUOUS
SIMILARITIES
Both refer to differences in inherited traits that exist among members of a
species.
DIFFERENCES
Have no distinct categories into Have distinct categories into which
which individuals can be placed individuals can be placed
Tend to be quantitative Tend to be qualitative
Are controlled by a large number of Are controlled by a one gene or a
genes (polygenes) small number of genes
Are significantly affected by the Are largely unaffected by the
environment environment