1
Q
What is evolution?
A
- Evolution is the theory that describes the way in which organisms evolve or change over many years as a result of natural selection
- Organisms better suited to their environment are more likely to survive and reproduce, passing on their characteristics to their offspring
- Gradually, a species change over time to have a more advantageous phenotype for the environment in which it lives, as it passed from one generation to the next by genes.
2
Q
What did Darwin observe on the Galapagos?
A
- Islands had different flinches
- They were similar in many ways, but had different beaks and claws of different sizes and shapes
- The design of the flinches beak was linked to the foods available on each island
- A bird with a better suited beak to the food available would live longer than a bird who’s beak was less suited
- Therefore they would pass this trait onto their offspring and over time the finch population on their island would share this characteristic
- Presented the theory of evolution by natural selection
3
Q
What are the 3 evidences of evolution?
A
- palaeontology- study of fossils and the fossil record
- Comparative anatomy- study of similarities and differences between organisms anatomy
- Comparative biochemistry- similarities and differences between the chemicals makeup of organisms.
4
Q
What is palaeontology?
A
- Fossils are formed when animals and plant remains are preserved in rocks.
- Over long periods of time, sediment is deposited on to the earth to form layers (strata) of rock.
- Different layers correspond to different geological eras
- Fossils van be dated to put fossil organisms in a sequence
- Similarities can be shown
- However, it is not complete because soft bodied organisms can decompose quickly before they had the chance to fossilise
5
Q
What is comparative anatomy?
A
- A Homologous structure is a structure that appears structurally similar and may perform different functions in different organisms.
- Example is pentadactyl limbs
- Vertebrate limbs are used for a wide variety of functions such as running, jumping, hoping and flying,
- The basic structure of limbs are adapted to carry a wide range of functions, since they come from the same common ancestor.
- Presence of homologous structures provides evidence for divergent evolution
- Convergent evolution is when unrelated organisms have similar structures that have similar structures
6
Q
What is comparative biochemistry?
A
DNA found in the nucleus of cells can be sequenced and used to provide evidence of evolutionary relationships between species and how genetic code of species have changed over time
- DNA hybridisation: enzymes are used to cut up DNA and an electric current is run through so they are attracted to the negative end
- pattern in which they move can be compared
- degree of similarities in the DNA sequence can determine evolutionary relationships
- more closely related, more hydrogen bonds and higher temps are needed to break the hybrid DNA (2 strands stuck together)
7
Q
What is behavioural evidence?
A
Humans are classified as primates because
- longer period in parental care
- live in social groups
- vocalisation and facial expression
8
Q
What is the immunological evidence?
A
- how different immune system responds
- inject rabbit with human serum (blood without cells)
- the rabbit will develop antibodies against the antigens
- more green cloud= more precipitation=more in common as the rabbit and chimp antigens react
