Science: Evolution Test
What allowed for the variation in forkbird beaks?
Mutations
Based on the graphs, place the four different classes (reptile, fish, amphibian and mammal) in order, based on when they first appeared in the fossil record.
Fish, amphibian, reptile, mammal
Explain the process of natural selection. Use the neck length of giraffes to help explain.
A mutation in the giraffe population produced variation in neck length. Some giraffes had slightly longer necks than others. The giraffes with the longer necks have an advantage in getting more food...allowing the giraffes to survive long enough to reproduce. Every generation, more longer-necked giraffes survive. Over time, the giraffe population comes to have the adaptation of longer necks.
How do scientists determine how do divide geologic time into periods?
Based on the first or last appearance of certain of fossils (index fossils)
Why do scientists create stratigraphic columns?
As a record of the rock layers and fossils they observed in different locations
Consider the following situation: Turtles compete with one another. A faster turtle is more likely to escape from a predator. Over many generations, the average speed of turtles increases. - How would Lamarck explain this?
As turtles move to escape predators they become faster (they acquire speed). This trait is passed to offspring.
Explain why scientists think the dinosaurs went extinct. When did this occur?
At least one enormous asteroid crashed into Earth 65 mya. This created a huge cloud of dust/debris that blocked out the sun's light for a long period of time...disrupted the food web, caused global cooling, etc.
List two types of organisms that first appeared on Earth.
Bacteria and algae
Why is variation needed in the process of natural selection?
Creates a competitive advantage for some birds (2-tined forkbirds would be equally likely to get food)
What evidence do we need to know if the larger print came from a larger/heavier organism?
Depth of the footprints
List two factors that contributed to the extinction of the mammoth.
End of ice age (change in climate), human hunting
What is the difference between an observation and inference?
Example - The large tracks became more widely spaced (observation); the organism started to run (inference).
What are some possible explanations for the disappearance of a family from the fossil record?
Extinct, did not fossilize
List examples of trace fossils.
Footprints, trails, borrows, egg shells, feces
What do modern scientists use to determine how closely related two organisms are?
Genetic Evidence
How can you use rock layers to determine which fossils are likely to be from an extinct species?
If they disappear from the fossil record and do not reappear.
How did so many cichlid species come to exist in Lake Victoria?
Lake Victoria provides a large number of different habitats. Cichlids became adapted to their specific habitat. Over time, the cichlids became so different that they were not able to reproduce successfully with each other (speciation).
What can you infer about the changes in habitat that occurred at the same time as these changes?
Lived only on land...lived on land and in shallow water...lived in water
List two factors that have caused the decline of the Asian elephant.
Loss of habitat, human hunting
What kinds of skeletal changes appear to have occurred during the evolution of whales?
Loss of hind limbs, front limbs changed to fins, longer/stronger tail, more streamlined body, many more!
Why is the Cenozoic Era often referred to as the "Age of Mammals"?
Mammals really increased in diversity (404 new families)
Why is referring to the Cenozoic as the "Age of Mammals" misleading?
Many other animals thrived during this time period.
What types of organisms are often preserved in fossils?
Organisms with hard body parts (bones, shells, exoskeletons); aquatic organisms
During which time period did life on Earth really diversify?
Paleozoic
What could explain the appearance of a family in the fossil record?
Newly evolved, began to fossilize, large increase in the population
If you don't find fossils from a particular organism in a rock layer, can you conclude that the organism did not exist during that time period?
No! The soil conditions may not have been suitable for fossils to form.
Are mutations always harmful? Explain using beaks as an example.
No, a mutation creating a larger beak could allow birds to each larger seeds and nuts.
Why are organisms with little variation more at risk of becoming extinct?
Not much variation for natural selection to act upon. If environmental change occurs and it negatively impacts one organism in a species, it would impact the entire species the same way.
List two examples of animal adaptations.
Odor, camouflage, poison, speed, shells, sounds, etc.
List the time periods in order from the oldest to the most recent.
Pre-Cambrian (4,500 - 550 mya), Paleozoic (550-245 mya), Mesozoic (245-65 mya), Cenozoic (65 - 0 mya)
Which time period represents the longest amount of time (84%)? Shortest (1%)?
Pre-cambrian (longest) - Cenozoic (shortest)
List three factors that drive natural selection.
Predators, prey (food), mates
Describe the ground conditions for the footprints to have become preserved
Soft sediment; a layer of soil must have deposited fast enough to cover and protect the tracks.
How do we know about prehistoric organisms that lived thousands or millions of years ago?
Study fossils
What did Darwin notice when studying the Galapagos finches?
That they differed in size, color and beak shape/length (beak was adapted to food available)
List two things you can learn about evolution by comparing fossil records?
The order different animals evolved; how closely related one group of animals is to another; when animals went extinct
List two reasons that there are very few fossils from the Precambrian.
There was nothing alive that easily fossilized; older rocks have been subjected longer to the various forces of nature (erosion, heat and pressure of burial, etc.).
How can you determine if two organisms lived at the same time?
They are found in the same rock layer.
Consider the following situation: Turtles compete with one another. A faster turtle is more likely to escape from a predator. Over many generations, the average speed of turtles increases.How would Darwin explain this?
Turtles vary in speed. The faster turtles are better able to escape predators than slow turtles; therefore, the fast turtles survive longer to reproduce (and pass on their genes for speed).
Why is Darwin's theory of evolution more convincing than Lamarck's theory?
We know (after studying genetics) that acquired traits are not passed to offspring.
What types of information can fossils provide about organisms?
What it looked like, how it lived, what and how much it ate, etc.
At what point are organisms that were once one species considered to be 2 different species?
When the organisms can no longer reproduce successfully with one another
When is an organism considered to be extinct?
When there are no surviving members of that species
When is an organism considered to be endangered?
When they have such a small population that they are in danger of becoming extinct.
