EVOLUTION
Topic 4 - 2015
Year 10 Biology
TOPIC 4 – EVOLUTION
Things to cover:
1. History of Evolution
2. Natural selection
3. The Environment & Evolution
4. Artificial selection
Work to do:
1. Worksheet – Natural selection, Evolution & Speciation
2. Worksheet – Isolating mechanisms & Evolution
3. Worksheet – Evolution & continental drift
Suggested questions:
1. Textbook Qs – Ex3.2– p121 – Q1, 4-5, 8, 11
2. Textbook Qs – Ex3.3 – p127 – Q1, 4-5, 11
3. Textbook Qs – Ex3.4– p130 – Q1-4, 9
Ideas to know:
 Jean B. Lamarck
 Charles Darwin
 Alfred Wallace
 Alfred Wegener
 Natural selection
 Survival of the fittest
 Selection pressure
 Speciation
 Variation
 Adaptation
 Extinction
 Artificial selection
REVIEW
Topic 1
•
DNA is composed of ____________________ .
•
Each nucleotide consists of:
− A ____________________ sugar
− A ____________________ group
− A ____________________ base (_____ types)
•
The nucleotides form chains. Two chains twist to form the ____________________ shape of
the DNA molecule.
•
Chemical bonds hold the DNA molecule together. Strong ____________________ bonds hold
the nucleotides together, while weak ____________________ bonds form between the
bases.
Topic 2
•
DNA is coiled up tightly to form _______________
•
There are _______________ of chromosomes in every cell.
•
Most of these are _______________ , controlling general characteristics.
•
One pair are the _______________ , controlling both sexual and general characteristics.
•
Cell division is necessary for ____________________, ____________________ and
reproduction.
•
One type of cell division, ____________________, is used in the formation of new body cells.
It is also used by unicellular organisms for ____________________ reproduction. The
__________ daughter cells formed are ____________________ to the parent cell and have
__________ chromosomes.
•
The other type of cell division, ____________________, is used to form sex cells. Another
name for the products of this type of division are ____________________ This process takes
place in the reproductive organs. The __________ daughter cells formed are
____________________ to the parent cell and have __________ chromosomes. They are also
____________________ in size.
•
In order for cell division to occur, the DNA must ____________________ and the
chromosomes must divide equally between the cells.
•
____________________ can occur if this does not happen correctly. For example, disorders
involving additional or missing ____________________.
•
Down Syndrome is one example. This disorder results from the presence of
____________________ Chromosome 21. This is called ____________________ 21.
VARIATION
HISTORY OF EVOLUTION
•
The Book of ____________________ states that the world was created by a divine being in
six days.
•
Still a widely held Theory of Evolution known as “___________________________________”.
•
The Greek philosopher ____________________ perceived a “ladder of life” where simple
organisms ____________________ ____________________ to more
____________________ forms.
1785:
•
James ____________________ believed that the earth was formed by an ancient progression
of ____________________ ____________________, including erosion, disruption, and uplift.
1798:
•
Thomas Malthus
− proposed idea that populations ____________________ ____________________
____________________ than they can ____________________
•
Georges Cuvier
− suggested that the earth was ____________________ years old
− is well known for establishing ____________________ as a fact
1809:
•
Jean B. ____________________ proposed the Theory of ____________________
____________________
•
This states that ____________________ ____________________
in an organism’s life time are ____________________ to
____________________.
•
For example, the neck of the giraffe stretched as it reached
for food and its offspring would retain this longer neck.
1830:
•
Charles Lyell published evidence suggesting the age of the
earth was ____________________ __________________ years.
HISTORY OF EVOLUTION
1844:
•
________________________________________
•
Established that all species of life have descended over time from
________________________________________.
•
He proposed that this ____________________ pattern of evolution resulted from a process
that he called ____________________ ____________________.
1859:
•
____________________ ____________________
•
Developed a concept of evolution similar to Darwin's.
•
Independently proposed a theory of evolution due to natural selection that prompted
Charles Darwin to publish his own theory.
1915:
•
Alfred ____________________
•
Proposed a theory of ____________________ ____________________, which hypothesized
that the continents were slowly drifting around the Earth.
WHAT IS evolution?
•
Evolution involves ____________________ which are ____________________ (ie. Involves
DNA & genetics!).
•
Evolutionary change is usually ___________________ and may take ____________________
to show up, especially for organisms of long generation time (eg. ____________________).
•
For evolution to happen, 2 things need to occur:
1.
− resulting from ____________________, ____________________ and
____________________
2.
− caused by ____________________ ____________________
WHAT IS natural selection?
•
Charles Darwin’s theory
•
He suggested that, within a species, the individuals with ____________________ that
____________________ their environment ____________________ to
____________________ and ____________________ their variation to their
____________________.
•
Another way of saying this is that they are ____________________ survival by their
____________________.
•
Individuals with unadapted variations are said to be ____________________
____________________.
•
These either fail to ____________________, or, if they do survive, do not
____________________ as successfully.
•
Overtime, they will become ____________________.
WHAT IS natural selection?
•
In the following generations:
− there will be an ____________________ in the proportion of ____________________
individuals
− and a ____________________ in proportion of ____________________ individuals
•
The result is the ____________________ of the ____________________.
•
Over many ____________________, populations become more and more different from each
other so that eventually, ____________________ ____________________
____________________.
•
The new species will no longer be able to mate successfully with the old species.
Quick guide to Natural Selection:
1. ____________________ of ____________________ occurs
2. ____________________ exists in a population
3. ____________________ ____________________
4. ____________________ ____________________ one variant and ____________________
another
5. ____________________ ____________________ variant survives to
____________________
6. ____________________ becomes ____________________ ____________________ in
population
The ENVIRONMENT & EVOLUTION
•
A major driving force behind evolution is the ____________________ in which the species
lives.
•
____________________ ____________________ in the environment influence the survival
chances of an individual in that environment
•
Selection pressures may be:
− Biotic = ____________________
•
eg. ____________________, ____________________, ____________________,
____________________, ____________________
− Abiotic = ____________________
•
eg. ____________________, ____________________, ____________________,
____________________, ____________________
•
The result of this selection is ____________________.
•
If a species is somehow ____________________ into two groups by an
____________________ ____________________ or barrier, one species could potentially
____________________ into two.
•
If the ____________________ on either side of the barrier are ____________________, each
environment will ____________________ a different ________ of ____________________.
•
The two isolated groups ____________________ ____________________, so there is no
____________________ ____________________ between them.
•
After a long period, the groups on either side of the barrier may become so different that
they can no longer interbreed even when put together.
•
One species has ____________________ into two = speciation
•
Two examples of evolution in response to environmental change include:
1. Biston betularia  the peppered moth
2. ____________________ ____________________
____________________ in ____________________
The ENVIRONMENT & EVOLUTION
Example: The peppered moth
•
One of the earliest and best documented cases of natural selection.
•
Up until mid 19th century, most peppered moths were _________________ in colour.
•
This allowed them to be __________________________________ on the light coloured
_________________ on the trees and rocks.
•
A black _________________ form did exist, but numbers were _________________ because
they were easily seen by _________________.
•
As _________________________ spread, soot and _________________ increased the
number of lichens being killed off and also resulted in the tree trunks being much
_________________.
•
The numbers of the ______________________________ increased and the numbers of the
light form decreased because the light form now became more visible to predators.
Artificial selection
•
Dogs are a great example of evolution in action.
•
All dogs are members of the exact ____________________ ____________________:
Canis lupus familiaris
•
All dogs, whether Chihuahua or Great Dane, are ____________________ of
____________________ and ____________________ ____________________
____________________
— but there may be some ____________________ complications involved here.
•
____________________ selection works like ____________________ selection, in that only
individuals with certain traits get to have offspring.
•
The main difference is that in artificial selection, ____________________ are selecting
certain traits, and with natural selection, individuals with traits allowing survival and
reproductive success do the best.
•
Artificial selection in dogs has occurred over thousands of years, a relatively small time
interval in the grand scheme of evolutionary time.