SBI 3U - UNIT 2

EVOLUTION

“Nothing in biology makes sense except in the light of evolution.”

Theodosius Dobzhansky

Hypothesis - a tentative assumption made in order

to draw out and test _________________________

A hypothesis can be ____________________through

____________________. A hypothesis can be

_______________, but not _________________.

 

A scientific theory summarizes a ________________________

that have been supported with ____________________. A

theory is valid as long as _____________________________.

Therefore, theories can be ___________. Basically, if evidence

________________to support a hypothesis, then the

hypothesis can become ___________________________of a

phenomenon. One definition of a theory is to say it's an

_____________________________________.

Theory

Stephen Hawkin:

"A theory is a good theory if it satisfies two requirements: It must

accurately describe _____________________, and it must make

definite ______________ about the results of __________________."

"No matter how many times the results of experiments agree with

some theory, you can never be sure that the next time the result will

not contradict the theory. On the other hand, you can disprove a

theory by finding ______________________________________ with

the predictions of the theory."

Evolution Isn't Evolution Just a Theory

- Cell Theory

- General theory of relativity

-Wave theory of light

The theory of evolution and common descent ________________

_________________ in scientific circles.

This is ______________________. Debates continue about how

_______________of evolution work.

However, evolution is now a modern science and is ____________

_____________________________________________________

_____________________________________________________

Evolutionary Theory

Evolution - the process in which significant changes in ____________

_____________________________________

For centuries scientists have been making careful observations,

formulating and testing hypotheses, analyzing data from diverse

sources and have drawn inferences to develop the theory that is now

accepted as the solution to the puzzle of evolution.

Like all scientific theories _____________________of evolutionary

biology are based on __________________________and

interpretation __________________________________________.

History of Evolutionary Theory

Paleontology (systematic study of fossils)

•Began in the 18th century by _____________________.

•Cuvier made many discoveries including:

•Many fossils __________________________________!

•Fossils of simple organisms could be

_____________________

•Fossils of complex organisms were ______________________

•More recent fossils were more likely _____________________

•Each layer contained ___________________not found above

or below.

These findings puzzled Cuvier, as he did not believe ___________

________, he believed ___________________________.

He came up the theory of ______________________. He said that

local ____________________could cause widespread _________,

and new species would be _____________________________.

This could account for the ______________________in strata

layers, but it could not account for the ______________________.

The other problem for Cuvier was that there was no precise method

for ________________________________________________________

Age of the Earth

Radioisotopes are atoms that _____________________. These

atoms have an __________________________and will undergo

__________ to become ________ atoms.

(Isotopes have ______________________________________)

Ex.  235U decays into __________

 14C decays into __________

It is the ______________that makes radioisotopes so valuable, because

the ___________________.

The time it takes for ________________________________is called the

_______________.

Ex.

Half-life is unaffected by ______________________ or other

environmental conditions.

With the discovery of Radioisotopes came the technique of _________________which

uses _______________________________________.

Ex. A sample of igneous rock contains small amounts of radioactive potassium and argon.

Using the ratio of 40Ar to 40K , it is determined that only 25% of the original parent

potassium isotope remains. How old is this rock sample?

1. A sample of igneous rock is found to contain the radioactive parent and daughter

isotopes uranium, 235U, and lead, 207Pb, in the ratio of 12.5%:87.5%. Assuming that

no 207Pb was present when the rock first formed, estimate the age of this sample.

2. A fossil skull of Homo neanderthalensis, is discovered in northern Europe and is

tested using carbon-14 dating. Palaeontologists are curious about whether the

Neanderthal was living at the same time as members of H. sapiens, thought to have

been living in the same area of northern Europe 45 000 years ago. Measurements

suggest that, of the original amount of carbon-14 isotope present in the skull when

the Neanderthal died, only 1.56% remains in the fossil fragment.

(a) How old is the fossil?

Using this type of dating the following has been found:

 All meteorites to hit the earth have ________________________________.

 Moon rocks have all been dated to about ________________________

 Oldest rock on earth dated to ____________________________.

 This leads us to believe that _____________________________________.