AP Biology Flashcards: Natural Selection
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 11 cards to help you master important concepts.
How does variation at the molecular level relate to an organism's fitness?
Variation in the number and types of molecules within an organism's cells can directly connect to its fitness by affecting its traits and functions.
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How does variation at the molecular level relate to an organism's fitness?
Variation in the number and types of molecules within an organism's cells can directly connect to its fitness by affecting its traits and functions.
On what does natural selection act?
Natural selection acts on the phenotypic variations present in populations.
Explain the link between molecular variation, phenotypic variation, and fitness.
Variation in molecules can lead to phenotypic variation, which natural selection acts upon. These variations can increase or decrease an organism's fitness in its environment.
How can molecular variation benefit an entire population?
Variation in molecules within cells across a population can enhance its overall ability to survive and reproduce, especially in diverse or changing environments.
What are selective pressures?
Selective pressures are factors in a changing environment that influence the survival and reproduction of organisms within a population.
What is the relationship between environmental change and selective pressure?
Changing environments are the direct source of selective pressures on populations, favoring certain phenotypic variations over others.
A forest environment becomes significantly colder over time. Which individuals in a bear population are most likely to have increased fitness?
Individuals with phenotypic variations that are advantageous in the cold, such as thicker fur, would experience increased fitness due to the new selective pressure.
A new disease sweeps through a population of plants. Why is molecular variation within the population important for its survival?
Molecular variation could lead to some plants having a natural resistance (a beneficial phenotypic variation). This variation enhances the population's ability to survive the selective pressure of the disease.
Define 'fitness' in the context of natural selection.
Fitness is an organism's ability to survive and reproduce in a specific environment, which is influenced by its phenotypic variations.
How can a specific phenotypic variation affect an organism's fitness?
Depending on the environment, a specific phenotypic variation can either increase or decrease an organism's fitness (its ability to survive and reproduce).
What is the importance of phenotypic variation within a population?
Phenotypic variation is essential because it provides the raw material for natural selection; some variations may increase or decrease fitness in a given environment.