SB4 - Natural Selection and Genetic Modification ✓ Flashcards
SB4a - How do fossil remains provide evidence for evolution?
- Fossil remains of humans can show us the bone structure of previous species
- It also shows how the size of (volume) the skulls, increased over time, suggesting that the size of the brain increased aswell
- The fossils are dated by the layers under the surface that they are
SB4a - How do stone tools provide evidence for evolution?
- Stone tools show us what previous species of humans did and what they required tools for
- We can see that over time, they become more sophisticated, going from skining animals/cutting up meat to decorations
- Stone tools are dated by the rock that they are found in.
SB4a - Name the species of ‘human’ in order of their evolution, and describe the trend in skull volume.
- Adripithecus (Ardi)
- Australopithecus (Lucy)
- Homo habilis
- Homo erectus
- Homo sapiens
Increasing skull volume over time
SB4a - Why is it that fossil evidence may not provide conclusive evidence of human evolution?
- There are gaps in fossil evidence so scientists aren’t sure the species evolved from each other
- Not all fossils have been discovered
- Some fossils are destroyed so we cannot draw a conclusion from it
SB4a - What are the two types of evidence for evolution?
- Fossil remains
- Stone tools
SB4a - How did Leakey’s findings provide evidence for human evolution?
- He discovered many hominid fossils.
- In 1984, in Kenya, he discovered an almost complete 1.6 million year old skeleton, providing evidence that humans evolved in Africa
- The species was tall and strongly built
SB4a - Describe methods used by scientists to date tools
- Carbon-14 Dating - estimating the age of carbon-containing material found in the tool, whether it’s the handle or the fur
- Statigraphy - using the layers of sediment as an indication of the age of the tool
SB4a - What do Ardi and Lucy tell us about human evolution?
- Ardis 4.4 million years old - she had characteristics both ape-like (long arms, big toes), and human-like (walked upright)
- Lucy, whereas, is more adapted to walking than climbing.
SB4b - Describe Darwin’s theory of evolution through natural selection (6 marks)
- variation - most populations of organisms have individuals who are very slightly different to one another due to mutations
- over-production - most organisms produce mroe offspring than will survive to childhood
- struggle for existence - because populations do not generally increases rapidly in size, there therefore must be competition for survival
- survival - those with advantgeous characteristics are more likely to survive this struggle
- 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 ftime, the proportion of individuals with the advantageous characteristic increase and the poorly adapted characteristic will eventually bel ost
SB4b - Using the theory of natural selection, explain why not completing a course of antibiotics is so dangerous.
- The population of bacteria have variation in their resistance to antibiotics.
- The course of antibiotics kill most of the bacteria
- Before the course is finished, the only remaining bacteria are the most resistant
- If the course isn’t completed, the remaining (more resistant) bacteria will reproduce,
- This will produce another generation of highly resistant bacteria which the antibiotic will be less effective against
SB4c - Describe how Darwin’s theories were developed.
- After visiting the galapagos islands and seeing differences in the mockingirds of different islands he wondered if spcies changed how they look based on their surroundings
- After reading an essay by Thomas Malthus, he came to the conclusion organisms produce more offspring than could survive and so only the best suited survive
- Wallace wrote a letter to him saying he came to the same conclusion
- They both worked together and Darwin summarised their ideas in a book claled ‘on the origin of species’
SB4c - What is the pentadactyl limb and how does this provide evidence for evolution?
- The pentadactly limb is a limb that has 5 main bone structures and this is visible in many organisms from humans to bats to dolphins.
- As we all have the same 5 bone base structure, this suggests that we all have a common ancestor.
- However the layout of these 5 bones changed depending on the surroundings and conditions of a species.
SB4d - As you go further down the order of classification, what will happen to the species that are there?
They will have increasingly similar characteristics and genes.
SB4d- What is the bi-nomial system?
- Genus + Species
SB4d - What are the 5 kingdoms and the characteristics of each of these?
- Animalae: Multicellular. Nuclei are present but no cell walls
- Plantae: Multicellular. Nuclei, chloroplasts and (cellulose) cell walls are present
- Fungi: Multicellular (apart form yeast). live on dead matter. Nuclei and (chitin) cell walls are present.
- Protists: Mostly unicellular. Nuclei and cell walls present
- Prokaryotes: Unicellular. No nucleus, flexible cell walls
