EVOLUTIONTopic 4 - 2017

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 – Ch3.3– Q1-4

2. Textbook Qs – Ch3.4 – Q1,3-5,8,13

3. Textbook Qs – Ch3.5 – Q1-5,8-12

Ideas to know:

Jean B. Lamarck

Charles Darwin

Alfred Wallace

Alfred Wegener

Natural selection

Survival of the fittest

Selection pressure

Biotic

Abiotic

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

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.

WHAT IS 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 natural selection?

WHAT IS natural selection?

• 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 ____________________ ____________________

• 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 ____________________.

• 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 ____________________ occurs2. ____________________ exists in a population3. ____________________ ____________________4. ____________________ ____________________ one variant and ____________________

another5. ____________________ ____________________ 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 à the peppered moth

2. ____________________ ____________________ ____________________ in ____________________

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.

The ENVIRONMENT & EVOLUTION• 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.