SBI3U
Ms. De Sousa
What does the saying:
« Only the fittest survive »
mean to you?
 Organisms
that survive environmental
challenges are able to pass on their genetic
information to offspring.
 By
passing on the genetic information, their
species survive.
 The
varying interactions between species
and the envrionmental changes causes some
species to go extinct while others thrive.

Adaptations can by structural, behavioural or
phsyiological.
Structural Adaptation: physical features of an
organism like the beak on a bird or the fur on a
bear.
Behavioral Adaptation: Things organisms do to
survive.
Physiological Adaptation: changes or chemical
reactions that occur within an organism.
 Many
organisms are able to camouflage and
blend in with their environment which
enables them to escape predators.
 Organisms
undergo a variety of adaptations
that enable them to survive and escape
predators.
Adaptation: a structure,
behaviour or physiological
process that helps an
organism survive and
reproduce in a particular
environment.
 Hibernation
 It
is a physiological adaptation.
allows organisms to survive in harsh
conditions by keeping warm and preserving
their energy
 Mimicry
is a form of
structural adaptation,
where the animal is able to
imitate something other
than what it is.
 Butterflies
use it as a
protection mechanism to
trick predators into
thinking they are an
inedible species.
The intention of
mimicry is to draw
attention to yourself.
This is usually
achieved, through the
presence of bright
colours.
Clicker questions 1-2
 Adaptation
is due to gradual ,
accumulative changes that helps an
organism survive and reproduce.
 Adaptations
are a result of genetic
mutations in an organisms’ DNA.
 These
mutations must be heritable in
order for the adaptation to persist.
 As
a result of the mutations, there are many
variations that appear in the population.
 Although
a mutation may lead to variation,
not all variations become an adaptation.
Variations: differences
between individuals which
may be structural,
functional or physiological.

Depending on the environment,
certain variations will persist while
others do not.

If the variation enables an organism
to survive in an environment, the
organism will pass on the genetic
mutation to their offspring.

Those who survive have a greater
chance of passing on their genetic
information.
 Although
variations may not play a big role at
one point in time, as the environment
changes, that variation may become useful
to an organism’a survival.
 If
that organism survives, it is able to pass on
that trait to the offpsring allowing them in
turn to survive in such an environment.
 Although
organisms are part of the
same species, there is alot of
variation.
 Humans
have a great deal of
variation due to the random
combinations of alleles that we
inherit from our parents.
 The
different combinations of
alleles contribute to the variation
in phenotypes of many species.
 Mutations
: changes in the genetic material
(i.e. DNA) of an organism
 The
mutation in the nucleotide sequence
creates new versions of alleles.
 All
mutations happen spontaneously when
DNA is copied in the S phase.
CGA-CCA-ACG-GCG...
Amino Acids Produced: Arginine - Proline Threonine - Alanine ...
CGA-CCA-GAA-CGG-CG...
Amino Acids Produced: Arginine - Proline Glutamic Acid - Arginine ...
 Some
mutations can alter the
shape and function of a cell.
 The
organism has mechanisms
that are able to get rid of these
malfunctioning cells.
 If
the malfunctioning cell is
able to bypass this checkpoint,
it proliferates and
accumulated into a tumor.
Clicker question 3
 When
the environment changes, certain
mutations that were once unfavorable can
now be favourable.
 Selective
advantage: a genetic advantage
that improves an organisms’ chance of
survival, usualyl in a changing
environment.
 When
an organism has a mutation that has a
selective advantage, that orgnaism is favored
in terms of survival and reproduction.
Clicker question 4
 Bacteria
and viruses tend to have a rapid
rate of reproduction.
 Due
to the rapid reproduction, a mutation
that has a selective advantage can be spread
into a population quickly
 Thus,
when there is a change to the
environment, a whole population of
bacteria may be able to survive.
 This
may result in antibiotic resistance.
If a bacteria undergoes a
mutation that allows it to
survive against bacterial
drugs, it becomes resistant
to the antibiotic.
New populations of bateria
will grow and be ressistant
to the medication.