Environmental Science A - Unit 4 Exam Flashcards

Natural Selection and Evolution

• Natural selection is the process allowing living organisms to adapt and change over time.
• For natural selection to occur, a key condition is the production of more offspring than can survive, leading to competition.
• Genetic variation among individuals enhances the chances of survival and reproduction in changing environments.
• Fitness of an organism encompasses both its ability to survive and reproduce successfully.

Population Dynamics

• In a scenario with rabbits of varying coat colors, natural selection would favor brown rabbits, increasing their population due to reduced visibility to predators.

Biodiversity

• Biodiversity is defined as the variety of life on Earth, crucial for ecosystem resilience.
• A mutation is any alteration in the nucleotide sequence of an organism's genome, potentially affecting traits and functions.

Speciation

• Sympatric speciation occurs when two species, such as apple maggots and hawthorn maggots, evolve from a common ancestor while living in the same area without overlapping food sources.

Genetic Variation and Evolution

• Inbreeding reduces genetic variation, making populations less adaptable to environmental changes and hindering evolution.
• Genetic disorders are caused by mutations in genes or abnormalities in chromosomes.

Threats to Biodiversity

• Major causes of biodiversity loss include invasive species, climate change, and habitat fragmentation, which divides larger habitats into smaller, isolated areas.
• Habitat fragmentation disrupts the ecosystem and threatens species survival.

Invasive Species

• Invasive species, like kudzu and zebra mussels, are non-native organisms that can harm local ecosystems by outcompeting native species and disrupting food webs.
• The introduction of zebra mussels increases algal blooms, negatively impacting aquatic ecosystems by depleting essential nutrients.

Conservation Status

• A species is categorized as endangered when it faces a high risk of extinction in a specific area or globally, such as the Cross River gorilla with fewer than 2,500 mature individuals.

Endangered Species Act

• The Endangered Species Act is a program aimed at conserving endangered species and their habitats, protecting biodiversity.

Genetic Engineering and Gene Drive

• A gene drive is a technology that ensures a specific gene is inherited in future generations, potentially useful for eliminating invasive species or reducing pesticide use.
• Gene drives function by creating homozygous organisms for desired traits, enhancing their inheritance likelihood.

Inheritance Patterns

• In diploid organisms, genes are inherited from both parents, contributing to offspring genetic diversity and trait expression.