Review and Quiz

Unit 4 Evolution

• 1. What are the 4 requirements for Natural selection?

• 2. Using the field mouse as an example, a brown mouse lives in an area, explain using as many of your vocabulary terms as possible, how a change to the environment may lead to a change in their fur color over time. Underline each vocabulary term you correctly use in your explanation.

• 3. If I find out 2 organisms have homologous structures, what can I infer?

• 4. If I find out 2 organisms have analogous structures, what can I infer?

1. What are the 4 requirements for Natural selection?

• Nature selects the traits best suited for survival based on the following criteria:

• 1. organisms in a population are naturally different from each other.

• 2. the differences are inherited from their parents and can be passed on to their offspring.

• 3. Populations tend to overproduce, there is not enough food or resources for the number produced leading to competition

• 4. Some of the variations provide an advantage to the ability to survive and reproduce more offspring compared to the others with out that variation.

• 2. Using the field mouse as an example, a brown mouse lives in an area, explain using as many of your vocabulary terms as possible, how a change to the environment may lead to a change in their fur color over time. Underline each vocabulary term you correctly use in your explanation.

• Camouflage, fitness, natural selection, etc…

• 3. If I find out 2 organisms have homologous structures, what can I infer?

• They have a common ancestor but lived in different environments ( divergent evolution)

• 4. If I find out 2 organisms have analogous structures, what can I infer?

• They do not share a common ancestor but did perhaps live in a similar environment and develop similar adaptations ( convergent evolution)

Review topics

• Law of superposition! • What is it and what can we learn from it?

• What usually happens to make geologists change from one geologic time period to another? Hint what happened at the end of each era?

• What do scientist think caused the end of the Mesozoic era?

• What are some of the possible explanations for how this could have happened?

• Compare and contrast Biogenesis and spontaneous generation.

• Which is currently accepted?

• But which one would have had to occur for the VERY first cell to form?

Origin of life/ primordial soupor chemical evolution theory

• The most likely order of events for the origin of life in the oceans of early like is…

Primordial soup/ Chemical evolution

• abiotic synthesis of amino acids and other organic molecules

• synthesis of proteins • development of a genetic code ( RNA)• Cell membranes/ evolution of cells

What did Miller and Urey do?

Miller and Urey

• Did an experiment to try to determine what the earth’s early conditions were like and if they could recreate them and form life!

Were the first cells on earth prokaryotic or eukaryotic?

How do we know?

First life was prokaryotic single celled!

• Fossil evidence shows the first cells were like current Archaebacteria.

• Archaebacteria thrive in extreme environments of intense heat or pressure, and microfossils suggest early life forms lived in volcanic environments.

cyanobacteria• cyanobacteria contain green pigments and had

no nucleus.• Are they prokaryotic or eukaryotic?• With green pigment, what could they likely do? • What gas did they likely give off?• What layer of the early earth atmosphere did

this produce? • What did this allow to happen?

• cyanobacteria contain green pigments and had no nucleus.

• Are they prokaryotic or eukaryotic?• With green pigment, what could they likely

do? Photosynthesize • What gas did they likely give off? oxygen• What layer of the early earth atmosphere did

this produce? ozone• What did this allow to happen? Life to move

out of the oceans and on to the land!

endosymbiont theory

• What is it?

• What is the evidence for it?

• What 2 organelles are most likely formed by this process?

• What is it? How eukaryotic cells developed by prokaryotic engulfing each other and living in a symbiotic relationship.

• What is the evidence for it? • Double membranes ( due to phagocytosis of

one cell by another), own circular DNA, replicate, ribosomes…

• What 2 organelles are most likely formed by this process?

• Chloroplasts and mitochondria

Age of fossils

• What are these?

• What information do they give us?

• Relative age:• Absolute age:

Age of fossils

• What are these?

• What information do they give us?

• Relative age: the position of the rock layer• Absolute age: radiometric dating

What is the Currently accepted theory of Evolution?

Currently accepted theory of Evolution

• Evolution occurred due to random mutations leading to variations selected by nature to pass on to the next generation.

What is directional selection?

• Can you give an example of how it would look on a graph?

directional selection

• When a population is moving in one direction due to the environment selecting for one genotype over another.

• In this case for the darker color

• What is the difference between Mimicry and camouflage?

Mimicry VS camouflage

• Mimicry involved looking like a specific species to avoid being eaten or harmed.

• Camouflage is a way to hind in your environment.

• So are stick bugs using mimicry or camouflage? • Is the viceroy butterfly using mimicry or

camouflage?

Natural selection and evolution

• How are they related?

• Natural selection is a mechanism by which evolution occurs.

What do Homologous structures tell us about two organisms that

have them?

Homologous

• Homologous structures indicate a common ancestor

• Like ?

Analogous Structures

• Indicate no common ancestor! • But a common environment….convergent

evolution due to similar environmental situations like water or a need to fly.

• Insect wings and bird wings. A fish fin and a whale flipper.

What do Vestigial structures tell us about organisms?

Vestigial “left overs”

• Vestigial structures point to a common ancestor.

• Structures that have gotten smaller but show that they were once there and are no longer being used…show relationships.

Hardy-Weinberg principle

• Populations in genetic equilibrium.• Are the gene frequencies changing?

• Populations in genetic equilibrium.• Are the gene frequencies changing? • NO they are in equilibrium and must meet the

stict requirements!

biochemical evidence

• When we compare the similarities of DNA and gene sequences for specific proteins between different organisms we get biochemical evidence.

• The more closely related the less differences there are in the gene sequences.

• Such as comparing DNA sequences or the amino acid sequence of a protein.

Primates

• Show an increased brain cavity size over time.• This correlates with an increase in brain size

and complex thinking.

Primates

• Forward facing eyes provide?

• A prehensile tail is needed for what?

Primates

• Forward facing eyes provide?• excellent depth perception, like what was

needed for swinging from tree to tree! • A prehensile tail is needed for what? • Living in a tree! Holding on!

Australopithecus

• What did “Lucy” teach us?

Australopithecus

• “Lucy”indicates that bipedalism evolved before large brains!

• Kind of the missing link.

HOMO

• development of culture sets apart • • Homo sapiens sapiens from the earlier

ancestors to modern man.

Fitness

• Why do some organisms survive and others don’t?

Fitness

• Why do some organisms survive and others don’t?

• they have a natural variation that allows them to survive and reproduce better than the other organisms.

Genetic Drift

• Random. By chance• Founder effect and bottle neck are examples.• Does genetic drift effect small or large

populations the most?

• Small !