Origins of Early Earth
How old is the Earth?
Earth is approximately 4.54 billion years old.
Explain what 'survival of the fittest' means.
Organisms with beneficial traits survive and reproduce.
How does molecular biology provide evidence for evolution?
Similarities in amino acid sequences (proteins) give clues as to which organisms are most closely related.
TRUE or FALSE: The smallest level of evolution occurs in individuals.
FALSE! The smallest level that evolution can occur at is the population level.
What do cladograms show us?
A cladogram is a branching tree diagram that shows ancestral relationships among organisms. These diagrams show evolutionary relationships between different branches referred to as clades.
How long has life existed on Earth?
The oldest known fossils are approximately 3.5 billion years old, but some scientists have discovered chemical evidence suggesting that life may have begun even earlier, nearly 4 billion years ago.
What is the difference between Darwin's theory of evolution and Lamarck's theory of evolution?
Darwin - natural selection 'selects' beneficial adaptations for survival;
Lamarck - organisms acquire traits based on needs
How can Darwin legitimately argue about the imperfection of the fossil record and then go on to show how the fossil record can be used to support evolution?
A very small percentage of animals that have lived and died ever became fossils. Thus, many pieces of the puzzle are missing; some will never be found. Nonetheless, we have many, many fossils that illustrate evolutionary transitions between fish and amphibians, between reptiles and mammals, between dinosaurs and birds, and in many lineages such as whales and horses.
What are the 3 main causes of microevolution?
1. Genetic drift
2. Gene flow
3. Natural selection
Did humans evolve from monkeys?
Humans did not evolve from monkeys. Humans are more closely related to modern apes than to monkeys, but we didn't evolve from apes, either. Humans share a common ancestor with modern African apes, like gorillas and chimpanzees. Scientists believe this common ancestor existed
5 to 8 million years ago.
Where are the youngest rocks on the ocean floor located?
The youngest rocks on the ocean floor are located at the oceanic ridge, an underwater mountain range formed from the spreading of tectonic plates in the ocean. As the tectonic plates spread apart, molten magma is released into the ocean. It cools in the seawater forming new rocks that form underwater mountain ranges.
Which of the following assumptions or observations is NOT part of Darwin's idea of natural selection?
A) Populations produce more offspring than their environment can support.
B) Whether an organism survives and reproduces is almost entirely a matter of random chance.
C) Heritable traits that promote successful reproduction should gradually become more common in a population.
D) Organisms compete for limited resources.
B) Whether an organism survives and reproduces is almost entirely a matter of random chance.
The wings of a bird and the wings of a butterfly are an example of
Analogous structures
Human hunting in the 1890s caused the northern elephant seals population to decrease to 5 seals. Since hunting was controlled, numbers have risen to 30,000 but genetic variability is very low. This is an example of...
Bottleneck effect
Two populations of fish are separated by a strip of land that divides the lake into two bodies of water. Assume each side of the lake is identical and the selective pressures are identical. Over time the populations become quite different. This is caused by a phenomenon called...
Genetic drift is a change in allele frequencies in a population through random chance. It occurs over time and isn't a result of more fit organisms passing on their genes.
65 million years ago, a 6-mile wide asteroid hit Earth, a dust cloud blocked the sun. This caused temperatures to plummet which was the heart of the damage from the Cretaceous–Paleogene extinction event. Because of the worldwide climate disruption, it was responsible for the extinction of the dinosaurs. What did this extinction allow for?
The extinction of the dinosaurs marked the Age of Mammals. When dinosaurs roamed the Earth, mammals remained small and furry. And because dinosaurs went extinct, mammals emerged as the largest land animals at this time.
What are the 4 principles of natural selection?
overproduction, variation, competition, survive and reproduce
Describe why tail bones in humans are considered as vestigial structures.
When human ancestors learned to walk upright, the tail became useless for maintaining balance and mobility, and it slowly disappeared. Nowadays, the coccyx serves some secondary functions, such as being a site of attachment for muscles and ligaments of the pelvic floor, which could explain why it has not degraded further.
A small village in the Jammu and Kashmir state of northern India is also home to a remarkably high prevalence of deafness. The high frequency of deafness in the population is traced back to intermarriage and the genetics of one man who established the settlement in 1901 (His brothers also had the same genetic problem). This phenomenon is known as...
Founder Effect
List and describe the 3 types of natural selection.
1. Directional selection
2. Stabilizing selection
3. Disruptive selection
List and describe the 4 various plate boundaries.
Subduction, transform, divergent, convergent
A population of giraffes lives in a forest with trees of varying heights. Following a flood in the area, all shorter plants were destroyed and only tall trees remain. After many generations, it is noted that giraffes living in this forest have longer necks, on average, than giraffes living in the same forest prior to the flood.
What type of selection has occurred?
Directional selection is natural selection that favors a phenotype at an "extreme" for a particular trait. In this example, we are looking at the height trait. Individuals with taller phenotypes exhibit greater fitness due to their ability to reach the food source more easily.
The bones of a human arm are very similar to the bones in a bird’s wing and a dolphin’s flipper. What does this similarity in structure reveal about the ancestry of these animals?
This suggests that these are homologous structures. These organisms developed different functions, but have similarities in the structures.
A population of geese migrates from Canada to Florida every winter. Individuals from the Canadian population sometimes breed with native Floridian geese. What is this an example of?
Gene Flow
Researchers found that the sickle cell gene is especially prevalent in areas of Africa hard-hit by malaria. In some regions, as much as 40 percent of the population carries at least one HbS gene. Explain why!
In these areas, HbS carriers have been naturally selected, because the trait offers some resistance to malaria. Their red blood cells tend to sickle when they are infected by the malaria parasite. Those infected cells flow through the spleen, which culls them out because of their sickle shape -- and the parasite is eliminated along with them.