Natural Selection

Natural selection occurs when which of the following conditions are met?

• Individual organisms depend on each other to obtain available resources.

• Variations between individual organisms lead to differential survival chances.

• Habitat and nutrient resources in an area are plentiful over a long period of time.

• The conditions in an ecosystem support a wide range of living organisms

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The flightless cormorant (Bird) of the Galápagos Islands is the only cormorant bird that has lost its ability to fly. What is the most likely reason for this?

• This species existed for a long period of time in an environment with no natural predators and ample food on the ground.

• There are no trees on the island where this species lives.

• All members of this species that could fly left the island.

• Birds that live near the ocean do not need to fly.

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The image provided shows two distribution curves. Each graph shows the number of individuals with a certain body length. The graphs compare an original generation (Generation 1) with its descendants (Generation 100).

• By Generation 100, no individuals with a body length below 30 cm were able to reproduce.

• The optimal body length selected for by Generation 100 was approximately 45 cm.

• Environmental pressures over the generations selected for a body length increase of 10 cm.

• These organisms are unable to achieve a body length greater than about 50 cm.

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Invasive species of Asian carp introduced to the Mississippi River have thrived and are threatening to eliminate many native species of fish. Which of these could be a contributing reason why?

• These species of fish lay many more eggs than the native species.

• These species of fish eat a greater variety of foods than native fish, destroying entire ecosystems.

• These species can survive in more extreme temperatures and water with a lower oxygen concentration.

• All of these can be contributing reasons.

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For evolution to function, all the following characteristics of genes are necessary, EXCEPT–

• variation in genes in a population.

• genetic traits that are inheritable across generations.

• genetic information stored on chromosomes.

• genes resulting in traits that provide advantages.

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Describe how natural selection and evolution are related.

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Describe how fitness relates to an organism's ability to survive and reproduce.

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Explain the three (3) factors that interact to result in evolution.

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