History of Life on Earth

Vocabulary flashcards covering key terms and concepts related to the history of life on Earth.

Solar System

A gravitational system formed by the sun and the celestial bodies that orbit it.

Condensing Nebula

A cloud of gas and dust in space that forms the solar system.

Protocells

Membrane-like vesicles formed around organic molecules, resembling early cell structures.

Miller-Urey Hypothesis

An experiment that demonstrated how organic molecules could form under early Earth conditions.

Stromatolites

Layered sedimentary rock formations primarily formed by cyanobacteria trapping sediments.

Endosymbiosis

A relationship where one organism lives within the body of another and both benefit.

Asexual Reproduction

A mode of reproduction that involves only one parent, producing genetically identical offspring.

Cambrian Explosion

A significant event in Earth's history marked by a rapid increase in the diversity of life forms.

Eukaryotes

Organisms whose cells contain a nucleus; evolved from prokaryotic ancestors.

Photosynthetic Bacteria

Bacteria such as cyanobacteria that can perform photosynthesis, producing oxygen.

Why is variation in a gene pool advantageous?

More variation in a gene pool increases the chances of survival and adaptability of a population in changing environments.

How to calculate allele frequencies?

To calculate allele frequencies, divide the number of each allele by the total number of alleles in the population. For example, if there are 50 FF, 50 ff, and 50 Ff bunnies, the frequency of the F allele is (50 + 0.5*50) / 150 = 0.5 and the f allele frequency is (50 + 0.5*50) / 150 = 0.5.

How does allele frequency relate to natural selection?

Allele frequency changes in a population over time due to natural selection, as advantageous alleles become more common while disadvantageous alleles diminish.

What is directional selection?

Directional selection occurs when individuals with a particular phenotype are favored, leading to a shift in the population's phenotype distribution.

What is stabilizing selection?

Stabilizing selection occurs when individuals with intermediate phenotypes are favored, reducing variation and maintaining the status quo in a population.

What is disruptive selection?

Disruptive selection occurs when extreme phenotypes are favored over intermediate phenotypes, potentially leading to speciation.

What is gene flow?

Gene flow is the transfer of genetic material between populations, which can introduce new alleles and increase genetic diversity.

What is genetic drift?

Genetic drift is a random change in allele frequencies in a population, often having a more significant effect in small populations.

What is the bottleneck effect?

The bottleneck effect occurs when a population's size is significantly reduced, leading to a loss of genetic diversity.

What is the founder effect?

The founder effect occurs when a small group from a larger population establishes a new population, leading to reduced genetic variation.

How do mutations contribute to evolutionary change?

Mutations introduce new genetic variations, which can be acted upon by natural selection, leading to evolutionary change.

How does non-random mating contribute to evolutionary change?

Non-random mating can lead to changes in allele frequencies by favoring certain traits, affecting the genetic structure of a population.

What is sexual selection?

Sexual selection is a form of natural selection where certain traits increase an individual's chances of attracting mates, leading to the evolution of those traits.

Define speciation.

Speciation is the process by which new species arise from existing species, often due to reproductive isolation.

How does reproductive isolation lead to speciation?

Reproductive isolation prevents interbreeding between populations, allowing them to evolve independently and potentially become separate species.

Give examples of allopatric and sympatric speciation.

Allopatric speciation occurs when populations are geographically separated, while sympatric speciation occurs when populations are in the same area but become reproductively isolated.

What is the relationship between speciation and gene flow?

Speciation often occurs when gene flow between populations is reduced or eliminated, allowing for independent evolution.

Differentiate between convergent and divergent evolution.

Convergent evolution occurs when unrelated species evolve similar traits due to similar environmental pressures, while divergent evolution occurs when related species evolve different traits.

What is adaptive radiation?

Adaptive radiation is the rapid evolution of diversely adapted species from a common ancestor in response to different environmental challenges.

What is coevolution?

Coevolution is the process by which two or more species influence each other's evolution through mutual adaptations.

Differentiate between punctuated equilibrium and gradualism.

Punctuated equilibrium suggests that species remain stable for long periods, with rapid changes occurring during brief episodes, while gradualism proposes that evolution occurs slowly and steadily over time.

What gases were present in Earth's early atmosphere?

Earth's early atmosphere likely contained gases such as methane, ammonia, water vapor, and hydrogen, but lacked free oxygen.

What did the Miller-Urey experiment test?

The Miller-Urey experiment tested the hypothesis that organic molecules could form under prebiotic conditions similar to those of early Earth.

What evidence supports the endosymbiotic theory?

Evidence for the endosymbiotic theory includes the presence of double membranes, circular DNA, and ribosomes similar to bacteria in mitochondria and chloroplasts.

How did sexual reproduction impact evolutionary change?

Sexual reproduction increases genetic variation, which can enhance adaptability and speed up evolutionary change.

What organisms dominated the Paleozoic Era?

During the Paleozoic Era, organisms such as trilobites, brachiopods, and early fish dominated the landscape.

What is artificial selection?

Artificial selection is the process by which humans breed plants and animals for specific traits, a concept that influenced Darwin's theory of evolution.

What is natural selection?

Natural selection is the process by which individuals with advantageous traits are more likely to survive and reproduce, leading to evolutionary change.

What is fitness in evolutionary terms?

Fitness refers to an organism's ability to survive and reproduce in its environment, contributing to the next generation's gene pool.