3.1 Biodiversity & Evolution (DP IB Environmental Systems & Societies (ESS): HL): Flashcards

If an ecosystem is dominated by only one or two species, a pathogen targeting those species can wipe out the population, causing the entire ecosystem to collapse.

Genetic diversity is the diversity of genes found within different individuals of a species. It enables populations to adapt and survive environmental changes.

Genetic diversity within a population can help it adapt to changes in biotic and abiotic factors.

Evolution is the cumulative change in the heritable characteristics of a population or species over time.

Natural selection is the mechanism that drives evolutionary change by favouring individuals with characteristics best suited to their environment.

The result of natural selection over time is the biodiversity of life on Earth.

Evolution is the overall change in heritable characteristics of a population or species over time.

The theory of natural selection known as "survival of the fittest" was proposed by Charles Darwin.

Natural selection can take place over billions of years.

True.

All organisms, not just animals, experience selection pressures as a result of the environment they are in.

Individuals within a species show variation caused by differences in genes.

Because these individuals are better adapted to their environment, they are more likely to survive, reproduce, and pass their genes on to the next generation.

When organisms reproduce, they produce more offspring than the environment can support.

A selection pressure is an environmental factor that affects an organism’s chance of survival and reproduction.

Speciation is the generation of new species through evolution when populations become isolated and can no longer interbreed to produce fertile offspring.

Species richness is the number of species present in a community or defined area.

Species evenness is the relative abundance of each species in a community, indicating how evenly individuals are distributed among the different species.

Species richness can sometimes be a misleading indicator of diversity because it does not consider the number of individuals of each species.

Species diversity is more informative than species richness because it takes into account both the number of species (richness) and their relative abundances (evenness), providing a fuller picture of biodiversity.

False.

Areas can have the same species richness but different species evenness, resulting in different overall species diversity.

Species diversity considers both the number of species present and the evenness of their abundances.

A diversity index is a mathematical tool used to quantify the diversity of species within a community by considering both the number of species and their relative abundances.

Simpson's diversity index is a measure of diversity that reflects both species richness and evenness, with higher values indicating greater diversity.

Simpson's diversity index (D) is calculated as D = N(N-1) / Σn(n-1), where N is the total number of individuals and n is the number of individuals of each species.

A higher diversity index value indicates greater species richness and evenness.

True.

Simpson's diversity index is useful for comparing communities or monitoring changes in diversity over time.

Two sites may have the same species richness but different relative abundances of those species, affecting their species evenness and resulting in different Simpson's diversity index values.

The lowest possible value for Simpson's diversity index is 1.

Biodiversity is the variety of life on Earth, including ecosystems, habitats, species and genetic diversity.

Biodiversity is important for medicine and pharmaceuticals because many medicines are derived from different species, offering potential treatments for various diseases.

Biodiversity helps maintain ecosystem stability by making ecosystems more resilient to environmental changes.

Biodiversity contributes to local economies by supporting tourism, livelihoods, and providing resources.

Ecosystem resilience is the ability of an ecosystem to recover from disturbances and adapt to environmental changes.

The IUCN Red List categorises species based on their extinction risk.

Citizen science involves public participation in scientific research, with volunteers collecting data on local wildlife for use in conservation.

National agencies like Natural England in the UK collect data on local species and habitats by conducting surveys.

Parabiologists are local people trained to assist in biological research, bridging the gap between communities and scientists for conservation management.

A protected area is a region set aside to conserve ecosystems, habitats, or species, such as parks or reserves.

Habitat restoration involves restoring degraded ecosystems to their natural state, sometimes by reintroducing native species.

False.

Sustainable practices include agriculture, forestry, and fishing, not just agriculture.

Genetic diversity is the variation in genes between individuals within a species. This diversity is important for the survival and adaptation of populations.

A chromosome is a long strand of DNA tightly coiled together, found in the nucleus of cells.

A gene is a specific sequence of DNA that codes for a particular trait or protein in an organism.

A genome is the complete set of genes or genetic material present in an organism.

Humans have 46 chromosomes, arranged in 23 pairs. Each pair carries genes inherited from both parents.

The molecule that carries genetic information in all living organisms is DNA.

Mutations create new versions of genes known as alleles. These changes can introduce new traits into a population.

Mutations are random changes in the DNA sequence that can introduce new traits into a population.

False.

Most mutations are neutral, some can be beneficial and some harmful.

Sexual reproduction combines genetic material from two parents, creating offspring with a unique set of genes. Genetic recombination leads to new combinations of alleles.

The complete set of genes in an organism is called its genome.

Genetic diversity gives populations a greater ability to adapt to changing environments. Some individuals may have genetic traits that help them survive new threats.

Low genetic diversity increases the risk of inbreeding, which can lead to genetic disorders and reduced survival rates.

Reproductive isolation occurs when different populations of a species can no longer interbreed, preventing gene flow between them.

Reproductive isolation prevents gene flow between populations, leading to the development of new species.

The two main types of reproductive isolation are geographical isolation and ecological or behavioural isolation.

Speciation is the formation of new species when populations become reproductively isolated and accumulate enough genetic differences.

False.

Reproductive isolation can also occur due to behavioural or ecological differences, not just physical barriers.

Geographical isolation is when physical barriers like rivers or mountains separate populations, preventing interbreeding.

Speciation occurs when genetic differences between populations lead to the inability to produce fertile offspring.

An example is the bonobos and common chimpanzees, which became separate species after the Congo River separated their populations.

Behavioural isolation is when populations develop different behaviours that prevent them from interbreeding, even if they live in the same area.

The apple maggot fly became behaviourally isolated when some individuals began to lay eggs on apples instead of hawthorn trees.

Endemism is when a species is found only in a specific geographical area. It is common on isolated islands because geographical isolation leads to the evolution of unique species.

True.

Hawaiian honeycreepers are found only in the Hawaiian Islands and are adapted to specific niches there.

Mechanical isolation occurs when changes in genitalia make mating between individuals physically impossible.

A biodiversity hotspot is an area with a large number of different species, especially those that are endemic, rare, or endangered, and is under significant threat from human activities.

To qualify as a biodiversity hotspot, an area must have at least 1,500 species of endemic vascular plants and have lost at least 70% of its original natural vegetation.

To be considered a biodiversity hotspot, an area must have at least 1,500 endemic species of vascular plants and must have lost at least 70% of its original natural vegetation.

False.

The Amazon rainforest does not currently qualify as a biodiversity hotspot because it has not yet lost 70% of its original natural vegetation.

Biodiversity hotspots are critical for conservation because they contain many endemic, rare, and endangered species that are not found anywhere else, and are under severe threat from human activities.

Biodiversity is not evenly distributed across the planet. Hotspots contain more than half of the world’s plant species but make up less than 3% of Earth's surface.

The main threats to biodiversity hotspots are deforestation, pollution, and habitat destruction, mostly caused by human activities.

An endemic species is a species that is found only in a particular area and nowhere else in the world.

Tropical biomes have high biodiversity because their warm, wet conditions support a wide range of plants and animals.

The Coral Triangle in Southeast Asia is a tropical hotspot that is home to more than 600 species of reef-building corals.

High endemism means that an area contains a large number of species that are found only in that particular area.

Major biodiversity hotspots are found in the Amazon, Central America, Central Africa, and Indo-Malaysia regions.

Tropical biomes are mainly found between 15° north and 15° south of the equator.

Artificial selection is the process where humans deliberately choose organisms with desirable traits to breed.

Artificial selection is deliberate and directed by humans, while natural selection is driven by environmental pressures and is not deliberate.

Domestic dogs have been selectively bred by humans to have many different characteristics.

Artificial selection reduces genetic diversity because only individuals with specific traits are chosen to reproduce, so fewer different genes are passed on in the population.

Selective breeding in plants can increase crop yield and develop resistance to disease.

True.

Artificial selection reduces genetic diversity, making populations less resilient to diseases or environmental changes.

Evolution refers to the changes in genetic diversity of populations over generations.

Climate change is causing some Arctic animals, such as the polar bear, to adapt to warmer temperatures and melting sea ice.

Poachers targeted elephants with tusks, so tuskless elephants were more likely to survive and reproduce, causing the trait to become more common.

Overuse of antibiotics has led to the evolution of antibiotic-resistant bacteria, such as MRSA.

Habitat fragmentation creates new pressures, so native species must adapt or move away, leading to evolutionary changes in traits that help them survive in human-altered environments.

Natural selection is the process where traits that help organisms survive and reproduce become more common in a population over time.

The geological timescale is a framework that divides Earth's 4.5 billion-year history into sections to help scientists study changes in the planet and life over time.

The geological timescale provides a structure for understanding Earth's history and how life has evolved in response to changing environments.

False.

The geological timescale covers the entire history of Earth, including both geological and biological events.

A fossil is the preserved remains or traces of an ancient organism, providing evidence of past life on Earth.

By studying fossils, scientists can track how species have evolved and when different groups first appeared or went extinct.

The fossil record allows scientists to identify when new groups of organisms first appeared and when others went extinct.

The transition from fish to amphibians can be traced through fossil evidence, showing adaptation to land environments.

An eon is the largest division of the geological timescale, representing a major span of Earth's history marked by significant changes.

The correct order of divisions in the geological timescale is eons> eras> periods> epochs.

The four main eons are the Hadean, Archean, Proterozoic, and Phanerozoic.

The Mesozoic Era is known as the age of reptiles and included the dinosaurs.

The Cretaceous Period ended with the mass extinction of dinosaurs.

A mass extinction is an event where many species die out in a short time, reducing biodiversity and allowing new species to evolve.

A mass extinction is a widespread and rapid decrease in the diversity of life on Earth, where at least 75% of species are wiped out in a relatively short period of time.

There have been five major mass extinctions in Earth's history.

At least 75% of species must be wiped out for an event to be considered a mass extinction.

The Permian-Triassic extinction is known as the Great Dying.

The Ordovician-Silurian extinction mainly affected marine life.

The Cretaceous-Paleogene extinction caused the extinction of around 75% of species, including all non-avian dinosaurs.

Possible causes of the Permian-Triassic extinction include massive volcanic eruptions in Siberia, release of carbon dioxide causing global warming and ocean acidification, and methane gas release from melting ice.

Speciation is the process by which new species evolve, often rapidly after mass extinctions when ecological niches become available.

After the Cretaceous-Paleogene extinction, mammals diversified and evolved into many new species.

True.

Tectonic plate movement can cause volcanic eruptions and earthquakes, which can destroy habitats and release gases that contribute to mass extinctions.

Large meteorite impacts can block sunlight and disrupt photosynthesis, leading to food chain collapse.

The sixth mass extinction is an ongoing event caused mainly by human activities such as habitat destruction, climate change, overfishing, and pollution.

The Anthropocene is a proposed geological epoch during which humans have become the dominant force shaping the Earth's environment and climate.

No, the Anthropocene is not yet an officially recognised epoch, but it highlights the extent of human impact on the Earth.

Three major human activities are industrialisation, deforestation, and urbanisation.

The Anthropocene is marked by the permanent records of human activities on Earth's geology, atmosphere, and ecosystems.

True.

Scientists debate whether human impacts are enough to define a new epoch or if these changes are part of Holocene's natural variability.

One proposed start date for the Anthropocene is the Orbis spike dip in carbon dioxide levels around 1610.

The decline led to reforestation of previously farmed lands, which absorbed more CO₂, causing a detectable drop in atmospheric carbon dioxide known as the Orbis spike.

The burning of fossil fuels in coal-fired power plants created spherical fly ash particles, a marker of human impact beginning around 1950.

The 1964 spike in carbon-14 in the atmosphere was caused by nuclear weapons testing.

The Great Acceleration refers to the period after 1950 when human impacts on the environment, such as pollution and greenhouse gas emissions, increased dramatically.

Microplastics are small plastic particles produced by human activity that are accumulating in soils and sediments and will be preserved in the Earth's strata.

Human activities like agriculture, deforestation, and urbanisation are altering sedimentary systems by increasing soil erosion and changing river flows and coastal ecosystems.

Humans are creating new types of minerals and materials, such as concrete and plastics, that will persist in the geological record.