Flashcards in 7-Science-Evolution-Final Study Guide- AQs Deck (44):
When is an organism considered to be endangered?
When they have such a small population that they are in danger of becoming extinct.
When is an organism considered to be extinct?
When there are no surviving members of that species
Explain why scientists think the dinosaurs went exiting. When did this occur?
At least one enormous asteroid crashed into Earth 65 mya. This created a huge cloud of dust and debris that blocked out the sun's light for a long period of time. This disrupted the food web, caused global cooling, etc.
List two factors that contributed to the extinction of the mammoth.
End of the Ice Age and human hunting
List two factors that have caused the decline of the Asian elephant.
Loss of habitat and human hunting
How do we know about prehistoric organisms that lived thousands or millions of years ago?
What types of information can fossils provide about organisms?
What it looked like, how it lived, what and how much it ate, etc.
What types of organisms are often preserved in fossils?
Organisms with hard body parts (bones, shells, exoskeletons); aquatic organisms
List three examples of trace fossils.
Footprints, trails, borrows, egg shells, feces
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
What evidence do we need to know if larger prints come from larger/heavier organisms?
depth of the foot prints
What is the difference between a observation and an inference? List an example of each from one of the footprint cards.
It is a fact that the larger tracks became more widely spaced (observation), but it is only a theory or interpretation that it meant that the organism started to run (inference)
How do scientists determine how to divide geologic time into periods.
Based on the first or last appearance of certain fossils (index fossils)
List two types of organisms that first appeared on Earth.
bacteria and algae
List the time periods in order from the oldest to the most recent.
Precambrian (4.5 billion-550 million years ago)
Paleozoic (550-245 mya)
Mesozoic (245-65 mya)
Cenozoic (65 mya- present)
Which time period represents the longest amount of time (84%)? Shortest (1%)?
During which time period did life on Earth really diversify?
If you don't find fossils from a particular organism, can you conclude that the organism did not exist during that time? Why or why not?
No! The soil conditions may not have been suitable for fossils to form.
How can you determine if two organisms lived at the same time?
They are found in the same rock layer
How can you use rock layers to determine which fossils are likely to be from an extinct species?
If they disappear form the fossil record and do not reappear
Why do scientists creat stratigraphic columns?
As a record of the rock layers and fossils they observed in different locations
Turtles compete with one another. A faster turtle is more likely to escape from a predator. Over many gyrations, the average speed of turtles increases. Give an explanation for Lamark and for Darwin.
Lamark: As turtles move to escape predators they become faster (they acquire speed). This trait is passed to offspring.
Darwin: 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 Lamark's?
We know (after studying genetics) that acquired traits are not passed to offspring.
List two examples of animal adaptations.
Odor, camouflage, poison, speed, shells, sounds, etc.
Explain the process of natural selection. Use giraffe neck length as an example.
A mutation in the giraffe popultation produced variation in neck length. Some giraffes had slightly longer necks than others. the giraffes with the longer necks have an edvantage 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
List three factors that drive natural selection
Predators, prey (food), mates
What allowed for the variation in fork bird beaks?
Why is variation needed in the process of natural selection?
Creates competition (2-tined fork birds would be equally likely to get food)
Why are organisms with little variation more at risk of becoming extinct?
Not much variation for natural section 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.
Are mutations always harmful? Use beaks as example.
No, a mutation creating a larger beak could allow birds to eat larger seads and nuts.
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)
HOw did so many cichlid species come to exist in Lake Victoria?
Lake Victoria provides a large number of different habitats. Over time, the cichlides became so different that they were not able to reproduce successfully with each other (speciation)
What do modern scientists use to compare similarities and differences among species
List two things you can learn about evolution by comparing fossil records?
The order dfferent animals evolved; how closely related one group of animals is to another; when animals went exting
List two reasons that there are very few fossils from the Precambrian
There was nothing alive that easily fossilized; older ricks have been subjected longer to the various forces of nature (erosion, heat, and pressure of burial, etc
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, and mammal
What ae some possible explanations for the disappearance of a family from the fossil record?
Extinct, did not fossilize
What could explain the appearance of a family in the fossil record?
Newly evolved, began to fossilize, large increase in the population
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 kinds of skeletal changes appear to have occurred during the evolution of whales?
loss of hind limbs, front limbs change to fins, longer/stronger tail, more streamlined body
What can you infer about the changes in habitat that occurred at the same time as skeletal whale changes?
to land and shallow water animal
to water animal
How does DNA provide evidence about how species are related?
The more similar the DNA sequence the more closely related two species are