Life Diversity

• A species is a group of similar organisms that can reproduce to produce fertile offspring.
• Variation is the differences in characteristics in a population.
• There can be variation in physical characteristics but also behavioural, mental and personality characteristics.
• Some characteristics are inherited (natural hair and eye colour, skin colour) and some come from environmental factors (piercings, tattoos, scars).
• DNA is found in the nucleus of every cell. It is the genetic material that is responsible for passing of characteristics from parent to offspring.
• At fertilisation, the nucleus of the gametes fuse together to create offspring.
• Gametes contain 50% of the regular amount of DNA. This is so when the zygote forms, it will have the full amount of DNA.
• A mutation is a random change in the coding of DNA.
• A phenotype is a physical characteristic that we can physically see (eye colour, skin colour).
• A genotype is the genetic coding behind a persons phenotype. These may contain random mutations.
• A silent mutation is a mutation that cannot be physically seen.
• A genotype cannot be changed. A phenotype can change because of environmental factors.
• Siblings show variation as they come from different gametes and zygotes with different genetic coding and random mutations may occur during fertilisation that cause variation.
• Identical twins come from the same gametes and same zygote, meaning that their genetic coding is identical and the twins have identical genotypes.
• Artificial selection (selective breeding) is the deliberate breeding of individuals with characteristics seen as favourable or useful for humans.
• Inbreeding is when closely related individuals reproduce. This can cause genetic disorders and diseases that weaken the species.
• Adaptations are characteristics that allow an organism to better survive and reproduce in its habitat.
• Adaptations can be structural (to do with physical features), physiological (to do with process inside the body) or behavioural (to do with the organisms behaviours).
• Natural selection is when the most successful organisms survive and reproduce due to certain characteristics caused by random mutations, passing on their genes until a majority of the population possesses the advantageous characteristic.
• The theory of evolution states that all living things evolved over time through natural selection.
• New adaptations occur as a result of genetic mutations.
• Evolution is a change in inherited characteristics in a population over time due to natural selection.
• Speciation occurs when two populations become so different from one another they cannot interbreed anymore. This happened when there is a geographical barrier between the two populations.
• Extinction is when there are no living members of a species left on Earth.
• Extremophiles are organisms that can survive extreme conditions such as high pH, high pressure or extreme temperatures.
• Species can go extinct naturally due to changes in habitat, new predators or competitors, new diseases or natural disasters.
• Humans impact natural selection by introducing environmental changes that put pressure on existing ecosystems.
• Climate change impacts natural selection as species have to adapt to new conditions in their habitats.