·         Four processes would have needed to occur for the first cells to form

1.       chemical reactions to produce simple organic molecules from inorganic molecules

2.       assembling these simple organic molecules into polymers

3.       formation of polymers that can self-replicate – allowing for inheritance of characteristics

4.       development of membranes to form spherical droplets with an internal chemistry different from the surroundings including the polymers that held the genetics

·         recreating the probable conditions of Earth with ammonia, methane and hydrogen before living organisms. Electrical discharges and the boiling and condensing of water simulated lightning and rainfall, with the result being the production of 15 amino acids after one week

1.       chemical reactions in the Earth’s atmosphere

2.       hydrothermal vents in the oceans

·         RNA is both a catalysts and has the ability of self-replication

1.       RNA catalyses a broad range of reactions, could have taken on the role of proteins (enzymes) in the beginning

2.       RNA is capable of self-replication – one molecule can form a template for the production of another molecule (complementary base pairing)

·         both mitochondria and chloroplasts have evolved from independent prokaryotic cells, which were taken into a larger heterotrophic cell by endocytosis

·         The characteristics of mitochondria and chloroplasts supported by the endosymbiotic theory

1.       they grow and divide like cells

2.        they have a naked loop of DNA, like prokaryotes

3.       they synthesize some of their own proteins using 70S ribosomes, like prokaryotes

4.       they have double membranes, as expected when cells are taken into a vesicle by endocytosis

·         Problems with the definition of species

1.       there are species that cannot interbreed, but show no significant differences in appearance

2.       species that do not look alike can interbreed, producing hybrids

3.       some species always reproduce asexually, so the members of a population do not interbreed

4.       fossils are unable to be used to determine if two organisms interbred

·         occurs when members of a species migrate to a new area, forming a population that is geographically isolated (interbreeding is impossible due to isolation)

·         occurs when two varieties of a species live in the same geographical area, but do not interbreed

·         occurs when species become less and less similar over time (by becoming adapted to different environments, the species avoid competition with each other)

·         occurs when the process of evolution proceeds very slowly, but large changes can gradually take place over time

·         thought to be a more valid theory and involves the sudden changes, as new adaptations would be necessary to cope with changed environmental conditions, hence strong directional selection occurs

·         A population in which there are two alleles of a gene in the gene pool is polymorphic, and if one allele is gradually replacing the other allele the population shows transient polymorphism, e.g. peppered moth

·         occurs when the two alleles of a gene can persist indefinitely in the gene pool of a population, e.g. sickle cell anaemia

·         Humans are classified as primates as they have anatomical features that are characteristic of that order

1.       grasping limbs, with long fingers and a separated opposable thumb

2.       mobile arms, with shoulder joints allowing movement in three planes and the bones of the should girdle allowing weight to be transferred via the arms

3.       stereoscopic vision, with forward facing eyes on a flattened face, fiving overlapping fields of view

4.       skull modified for upright position

·         The half-life is the time taken for the radioactivity to fall to half of its original level, carbon dating and potassium-argon dating use this

·         Correlation between increasing brain size and change in diet

1.       eating meat increases the supply of protein, fat and energy in the diet, making it possible for the growth of larger brains

2.       catching and killing prey on the savannas is more difficult than gathering plant foods, so natural selection will have favoured hominids with larger brains and greater intelligence

·         Cultural evolution is the incorporation of new methods, inventions or customs into what has been passed through each generation

1.       cultural evolution does not involve changes in allele frequencies in the gene pool

2.       changes due to cultural evolution can happen during one human lifetime, whereas genetic evolution happens over generations, so cultural can be much more rapid

3.       cultural evolution involves characteristics acquired during a person’s life (nurture) whereas genetic evolution involves characteristics that are inherited (nature)

mouth - indicate a mainly vegetarian diet

·  brains were only slightly larger (in relation to body size) than the brains of apes