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Science 9
Unit A: Biological Diversity
Science InAction
Section 1.3: Pages 20-24
Section 2.1: Pages 26-29
Lesson #3
Learner Outcomes
I can identify the role of variation in species survival under
changing environmental conditions
I can describe examples of variation of characteristics within
a species, and identify examples of both discrete and
continuous variation
I can distinguish those characteristics that are heritable from
those that are not heritable, and identify characteristics for
which heredity and environment may both play a role
What is Variation?

Variability within a species
population.
Eg. Red/Blond Hair vs. Brown
Hair
Eg. Blue eyes vs. Green eyes

Examples of variability in
include:
Red fox (color of coat)
Antibiotic resistance
(bacteria)
 Banded snail (color and
design of shell)


Variation of Human
Physical Characteristics

Skin, eye, complexion
colouring

Hair colour, baldness

Supernumerary body
part (extra parts), or
missing body parts

Cleft Lip and Palate
Variation of Human
Physical Characteristics
Height – average
range
1. Dwarfism
2. Gigantism
 Blood type
- Groups A, B, AB, and O
 Somatotype
 Dominance of
handedness
 Dexterity and motor
skills

Who is This Man?
What is Natural Selection?

Happens when factors in the environment
determines, or “selects” which individuals,
within a species, will be able to survive.

Offspring will usually have similar
adaptations for survival.
Whales

Charles Darwin – Theory of Evolution –
“On the Origin of Species” book - 1859
The 5 year voyage of the
HMS Beagle
Surveying and charting coasts
Antibiotic resistance is
enhanced by natural selection
The top section represents a
population of bacteria before
exposure to an antibiotic.
The middle section shows the
population directly after exposure,
the phase in which selection took
place.
The last section shows the distribution
of resistance in a new generation of
bacteria.
The legend indicates the resistance
levels of individuals.
Variations
Variation is one of the most critical aspects of
species survival.
It may be:
1. a genetic (cellular code) modification
2. a behavioral tendency

This enables some individuals within a
species to survive, while others, will
perish.
Genetic Variability

Species of Side-blotched lizards (Uta
stansburiana) in central California
Give it a TRY – Page 27
Survey the class and find how many people:
a) Can or cannot bend their thumb joint
“backward” without adding pressure
b) Have earlobes that are attached or separate
c) Have a pointed or smooth hairline

Draw a data table to record your results.
Create a graph that will best illustrate
your results
Inheritance

Transmission of
characteristics from
parents to
offspring

The characteristics of
the parents are
carried to the next
generation by the
process of heredity
What are Non-Heritable Traits?

Characteristics are
acquired and not
necessarily passed on
from generation to
generation.

Athleticism, artistic
ability, leadership
qualities are all
learned during the
early years of life.
Continuous Variation

Variations are differences in characteristics
that have a multitude of variations, such
as height, shoe size, arm length etc…
Discrete Variations

Discrete variations are differences in
characteristics that have a definite
form.

One characteristic, or the single,
other variation, of the characteristic.

Either the organism has a trait or
it does not.
Example: Either your earlobes are
attached or they are not.
Variation and the Environment

Some variations may be influenced
by interactions with the environment.
These variations are not inherited.
Examples include:

Change in the pigmentation of skin
color throughout the seasons due to
the sun.

Height and weight can be
influenced by diet.
Give it a TRY – Page 29

Ready…………..set…………GO!!!!
Quickly clasp your hands together above
your head, interlocking your fingers.
Look to see which thumb is on top. Note which way
feels more natural.
Finish the chart in your notes, indicating Left Thumb
on Top vs. Right Thumb on Top
Decide whether the data is discrete or continuous.
Explain your answer.
Is it Discrete or Continuous?
Page 29
Action
Right
Preference
Left
Preference
Type
(circle one)
Clasping
Hands
Continuous
Folding Arms
Continuous
Discrete
Discrete
Sample Multiple Choice
Questions
Q1. To better understand variation; scientists
explore the characteristics, which are passed
on from generation to generation within a
species. Those characteristics that are
passed on from generation to generation are
…
 A. genetic
 B. inherited
 C. non-inherited
 D. non-genetic
Sample Multiple Choice
Questions
Q2. An albino kangaroo is a kangaroo that is
pure white. This characteristic is classified
as a …
A. non-inherited variation
B. continuous variation
C. discrete variation
D. singular variation
Sample Multiple Choice
Questions
Q3. Variations caused by interactions with
the environment are not heritable. Plants
that are grown in dim lighting conditions
would turn out to be …
A. identical to their parents in all aspects
B. much like their parents
C. very different from their parents
D. similar to parent plants that were
grown in dim light
Sample Multiple Choice
Questions
Q4. Cats B and C are similar in size, but cat A is taller when
standing. Like humans, cats pass down genetic information
for height, but cats can mature to be a wide range of
heights - it is not an "either/or" characteristic. The
characteristic of height in cats can be described as a
A.
B.
C.
D.
non-heritable and continuous in variation
heritable and discrete in variation
heritable and continuous in variation
non-heritable and discrete in variation
Answers to Previous
Questions
1. B
2. C
3. D
4. C
Did you …
… identify the role of variation in species survival under
changing environmental conditions?
… describe examples of variation of characteristics within
a species, and identify examples of both discrete and
continuous variation?
… distinguish those characteristics that are heritable
from those that are not heritable, and identify
characteristics for which heredity and environment
may both play a role?
Homework
 Read
pages 20-24, 26-29
 Check and Reflect page 29, #12, #5
 Update Portfolio
 Read pages 30-36
Question 1
Give one example of a heritable
characteristic and one example of a nonheritable characteristic that we did not
discuss in class.
Heritable
__________________________________
Non-Heritable
__________________________________

Question #2
What is discrete variation?
__________________________________
__________________________________
__________________________________
 What is continuous variation?
__________________________________
__________________________________
__________________________________

Question #5

A scientist wants to study continuous
variation in a mouse population. What
mouse characteristics would she or he
investigate?
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________