Topic 4- evolution

• Variation - most populations of organisms contain individuals which vary slightly from one to another.
• Over-production - most organisms produce more young than will survive to adulthood.
• Struggle for existence - because populations do not generally increase rapidly in size there must therefore be considerable competition for survival between the organisms.
• Survival - those with advantageous characteristics are more likely to survive.
• Advantageous characteristics inherited - better adapted organisms are more likely to reproduce successfully passing on the advantageous characteristics to their offspring.
• Gradual change - over a period of time the proportion of individuals with the advantageous characteristics in the population will increase compared with the proportion of individuals with poorly adapted characteristics, and the poorly adapted characteristics may eventually be lost.
• Resistance to antibiotics, mutants that survive antibiotic reproduce, their offspring possess resistance to antibiotics.
• Ardi (4.4 million years ago) - an ape-like creature, loosely associated with humans, with a small brain, ape-like body, and ape-like hands.
• Lucy (3.2 million years ago) - Human-like, walking upright (bipedal), therefore a change in the top of the spine and skull.
• Leakey (1.6 million years ago) - found evidence of early human ancestors in East Africa.
• Pentadactyl limb - shows common ancestor, used for different purposes ( flying, swimming etc).
• Kingdom - Animalia, Plantae, Fungi, Protoctista, Prokaryotes.
• Domain - Eukaryotes, Bacteria, Archaea.
• Tissue Culture - a technique of growing cells, tissues, organs or whole organisms in glass on artificial culture medium under aseptic and controlled conditions.
• Specific characteristics are selected and the 'best' of the offspring are bred to obtain the desired characteristics.
• Inbreeding maintains the traits of the breed but can be risky as it increases the chances of recessive or damaging trends coming together.
• Genetic engineering is the process of modifying the genetic material of an organism to produce a desired trait and removing unwanted traits.
• Genetic engineering, easy to grow (golden rice) - contains beta carotene which contains Vitamin A, which reduces blindness in children. However, relying on one crop reduces biodiversity.
• Herbicide resistant crops allow non-specific sprays to be used to control weeds. There are concerns that with increased use, weeds will become resistant and that there will be negative impacts on wild plants and biodiversity of farming.
• Fertilisers can increase crop yields but can pollute rivers and lakes. Biological controls (e.g: ladybirds) are often more ecological.
• Genetic engineering can be used to produce genetically modified organisms.