Grade 10 Biology Semester Exam: Evolution

Evolution

• Species: A group of organisms that can interbreed and produce fertile offspring.
• Gene pool: The total collection of all genetic variations (alleles) within a population.
• Allele frequency: The proportion of a specific allele in a population, reflecting evolutionary changes influenced by natural selection, genetic drift, and mutation.
• Speciation: The evolutionary process by which populations evolve to become distinct species, typically due to genetic isolation from lack of gene flow.
• Genotype and phenotype: In evolution, genotype refers to an organism's genetic makeup, while phenotype describes the physical and behavioral traits expressed as a result of interacting genotypes and environmental factors.
• Gene flow: The exchange of genes between populations, enhancing genetic diversity and reducing population differences.
• Genetic drift: A random event that causes a drastic change in allele frequency.
• Genetic bottleneck: A sudden reduction in the size of a population due to environmental events or human activities, leading to a decrease in genetic diversity and altering the population's genetic structure.

Natural Selection and Artificial Selection

• Artificial selection: When humans breed organisms for specific traits, like breeding cows and sheep for their milk and wool.
• Natural selection: The natural process where organisms better adapted to their environment survive and reproduce more successfully.

Comparison of Lamarck's Theory and Darwin's Theory

• Lamarck's theory: Organisms pass on traits acquired during their lifetimes.
• Darwin's theory of evolution: Inherited genetic variations advantageous for survival are naturally selected over generations.

Mechanisms of Evolution

• Variation: Individuals in a population differ in a trait due to differences in their genotype and/or phenotype.
• Inheritance: Traits can be passed on through generations.
• Adaptation: A trait or behavior that helps an organism survive and reproduce in its specific environment.
• Mutation: Caused by a mutagen or random mistakes in germ cells or during meiosis.
• Differential survival and reproduction (survival of the fittest): How well an organism can survive and reproduce.

Evidences of Evolution

• Comparative anatomy: Similarities and differences in the evolutionary paths that organisms take, determining the family of a certain species.
• Comparative embryology: Study of embryos and their development, proving that development/evolution happens because traits and structures occur and go away after time.
• Biogeography: Study of the patterns of geographic distribution of organisms and the factors that determine those patterns.
• Biomolecular evidence (DNA): DNA sequences in different species share similarities, indicating common ancestry.
• Fossil record (including transitional and index fossils): Fossil record documents the gradual changes in species over time, with transitional fossils showing intermediate forms between species and index fossils helping date the strata.

Evolution in Humans

• Homo: Genus including all ancestors of humans.
• Sahelanthropus: One of the earliest known hominins, dated about 6-7 million years ago, notable for features that suggest bipedalism and a mix of ape-like and human-like traits.
• Ardipithecus: Genus of early hominins known for species like Ardipithecus ramidus.
• Australopithecus: Genus of hominins that lived from about 4 to 2 million years ago, known for bipedalism and a slightly larger brain than earlier hominins.
• Homo habilis: 2.4-1.5 mya, made simple chopper tools.
• Homo erectus: 1.8 mya-200,000 ya, made spears, hand axes, and cleavers, used fire, and built branched-huts.
• Homo neanderthalensis: Stocky with broad noses and adapted to cold climates, went extinct 40,000 ya.
• Homo sapiens: Intelligent and adaptable, invented agriculture 12,000 years ago, and settled in farming communities.

Ecology

• Species: A group of organisms that can interbreed and produce fertile offspring.
• Habitat: The natural environment where a species lives and grows.
• Population: A group of individuals of the same species living in a particular area.
• Community: All the different species that live together in a particular area.
• Ecosystem: A community of living organisms and their interactions with their abiotic (non-living) environment.
• Biocenosis: The interacting organisms living together in a habitat or ecosystem.
• Abiotic factor: Non-living chemical and physical parts of the environment.
• Biotic factor: Living components of an ecosystem.
• Limiting factor: A factor that restricts the growth, abundance, or distribution of a population.
• Carrying capacity: The maximum number of individuals of a species that an ecosystem can support.
• Ecological niche: The role and position a species has in its environment, including all its interactions with biotic and abiotic factors.
• Biome: A large geographical area characterized by specific climate conditions, plant communities, and animal populations.
• Biosphere: The global sum of all ecosystems, encompassing all living organisms and their interactions with the Earth's atmosphere, hydrosphere, and lithosphere.

Ecology (continued)

• Producer: Organisms that produce their own food through photosynthesis or chemosynthesis.
• Consumer: Organisms that obtain energy by eating other organisms.
• Autotroph: An organism that produces its own food from inorganic substances.
• Heterotroph: An organism that cannot produce its own food and consumes other organisms.
• Levels of energy production and consumption: primary, secondary, tertiary, quaternary.
• Herbivores: Animals that primarily eat plants.
• Carnivores: Animals that primarily eat meat (other animals).
• Omnivores: Animals that eat both plants and meat.
• Prey: Animals that are hunted and eaten by predators.
• Predators: Animals that hunt and eat other animals.
• Apex predators: Top predators in a food chain with no natural predators.
• Detritivores: Organisms that feed on dead organic matter and waste.
• Decomposers: Organisms that break down dead organisms and organic waste, recycling nutrients back into the ecosystem.

Trophic Levels and Energy Flow

• Trophic level: The position that an organism occupies in a food chain, or the position of a group of organisms in a community that occupy the same position in food chains.
• Energy flow: Only 10% of the energy within a level is passed on to the next higher trophic level.

Food Chains and Webs

• Food chain: A linear sequence of organisms where each is eaten by the next member in the chain.
• Food web: A complex network of interconnected food chains in an ecosystem.

Pyramids of Energy, Numbers, and Biomass

• Pyramid of energy: A graphical representation of the energy flow in an ecosystem, with the base being the producers and the apex being the apex predators.
• Pyramid of numbers: A graphical representation of the population sizes in an ecosystem, with the base being the producers and the apex being the apex predators.
• Pyramid of biomass: A graphical representation of the total biomass in an ecosystem, with the base being the producers and the apex being the apex predators.