Biology Evolution

Give an example of evolution to adapt to specific environmental pressures
The Peppered Moth. Variation produced both white moths and black ones. During the Industrial Revolution (England) the air was full of soot and white trees went black. White moths stood out more and decreased their level of survival.
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Major Points of the Darwin-Wallace Theory
1. Variation 2. Struggle for survival 3. Better suited individuals 4. Increase survival and reproduction 5. Change of generations
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What is the evidence for Panspermia?
Amino acids found in meteorites in space such as glycine, could suggest that life originated from outer space.
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What is the evidence for life originated from Earth?
Miller-Urey experiments. From the Primordial soup, they produced amino acids (glycine, alanine, etc.)
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How did eukaryotes evolve from prokaryotes?
Prokaryotes living in colonies (stromatolites) underwent endosymbiosis e.g. chloroplasts and mitochondria. Evidence: bacterial ribosomes in mitochondria and mtDNA
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What features allowed eukaryotes to form multicellular organisms?
They were able to produce significantly more energy from 1 unit of glucose due to respiration and photosynthesis. Colonial organisms began to work together.
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Describe the process of fossilisation.
Animal dies. It is shortly covered by sediment. Increased pressure on sediment causes chemical change in sediment --> rock. Petrifying the organism.
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Three different ways that remains can be preserved?
1) Frozen 2) Acidic Peat 3) Amber
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What information can we get from indirect fossil evidence?
Coprolites and tracks provide behavioral evidence. Coprolites = diet, whilst tracks can identify gait, family units etc.
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What is punctuated evolution?
Following a dramatic change in the environment, a flurry of adaptations occur as a result of mutations. Beneficial alleles are passed on and evolution takes place.
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Why are so many unique species found on islands?
Isolation on islands prevents gene flow with the mainland. Adaptations to the island's environment remain unique to the island population due to reproductive isolation
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Why are wolves (placental mammal) and thylacines (marsupial) similar?
Example of analogous features caused by convergent evolution. Both have similar niches, so adaptations are advantageous to both species.
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Why are reptiles better suited to life on land than amphibians?
Amphibians need water to reproduce and remain hydrated. Reptiles are not tied to the water and can therefore prosper terrestrially.
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Why are trilobites and ammonites good index fossils?
Following the Cambrian explosion, trilobites were abundant. Their hard exoskeletons preserve well by fossilisation and so fossils are common.
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An explorer arrives on an island. What types of animals would he expect to see?
A unique array. Mammals are less likely due to mode of arrival on island. Some predators may be huge in comparison to mainland equivalent e.g. Komodo dragon, due to lack of competition. Others may be smaller e.g. Dwarf mammoth due to resources
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What methods are used to determine phylogenetic trees?
1. Physical features 2. DNA sequencing 3. Protein sequencing 4. Immunoglobulin evidence 5. DNA hybridisation 6. mtDNA (maternal lineage)
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Define: Homologous structures
A trait possessed by different related organisms derived from a common ancestor
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Define: Analogous structures
A trait possessed by different unrelated organisms as a result of convergent evolution e.g. butterfly wing and bird wing
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Define: Cline
A varying spectrum within a certain characteristic e.g. white moths --> light grey moths --> dark grey moths --> black moths
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Define: Stabilising selection
Within a stable environment, variation within the middle of the cline is most beneficial. Extremities are selected against. Mid-section variants survive and reproduce.
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Define: Vestigial organs
Organs found within modern descendants that no longer function as they once did for an ancestor e.g. human appendix or snake's tail bone
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Define: Geographical isolation
Physical barrier e.g. mountain range prevents gene flow from one population to another. Individual beneficial mutations in the separate populations are not exchanged --> speciation
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Define: Genetic Drift
Random decrease in a specific allele frequency (has the largest impact on smaller populations)
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Define: Population bottleneck
Reduction in the size of a population below 50% reduces gene pool and genetic variation
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What conditions need to be met for the Hardy-Weinberg Equilibrium to occur?
1. No mutations 2. Random mating 3. No immigration/emigration 4. Large stable population 5.One allele is not more beneficial than another
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What were the major features of the dinosaurs?
1. Laid hard-shelled eggs 2. Occupied every terrestrial niche 3. Cared for their young 4. Evolved from reptiles 5. Warm blooded
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When did the dinosaurs go extinct?
Meteor shower 65mya
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What type of dinosaur did birds evolve from?
Lizard-hipped dinosaurs
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Why did mammals and birds survive the mass extinction?
Major links in the dinosaurs food chains were severed and ecosystems broke down. Those that survived were small bodied, few in number, and fed on a variety of foods/ less specialised = less vulnerable
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What features of mammals make them so successful?
1. Fur 2. Care for their offspring 3. Milk for infants 4. Warm blooded 5. Enhanced vision and hearing
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What are the 5 characteristics of primates?
1. Opposable thumb 2. Large eyes at the front of the skull (3D vision) 3. 3D rotation of shoulder joint 4. Nails on sensitive fingers 5. Fur
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What species was 'Lucy'? What are some of her key features?
Lucy was an Australopithecus afarensis: 1. ape-like face 2. Long arms 3. Bipedal and arboreal 4. Sexual dimorphism 5. Small frontal lobe 6. FM at back of skull
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How do we know that bipedalism preceded increase in brain size?
Brain capacity did not really play a huge factor in human evolution until H. habilis. However, its ancestors e.g. A. africanus and Paranthropus Boisei were bipedal but had small brains
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What physical changes accompanied bipedalism?
1. Elongation and widening of the pelvis to support torso 2. Lengthening of the legs 3. Centralisation of the foramen magnum 4. Arched foot
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What is the significance of Homo habilis?
The handyman was the first human ancestor to use tools due to the increased capacity of its frontal lobe.
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How did the use of fire impact on Homo erectus?
Fire was used for protection against predators. They could cook their food and thus their teeth and jaw muscles changed.
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Why did H. neanderthalensis and H. sapiens vary?
The neanderthals occupied Europe during the ice age. They had a shorter limbs and a stockier frame to decrease their SA. H. sapiens were taller and leaner to increase SA
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Major Points of the Darwin-Wallace Theory


1. Variation 2. Struggle for survival 3. Better suited individuals 4. Increase survival and reproduction 5. Change of generations

Card 3


What is the evidence for Panspermia?


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Card 4


What is the evidence for life originated from Earth?


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Card 5


How did eukaryotes evolve from prokaryotes?


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