Revision notes for Phenology (Edexcel biology Unit 4 Topic 5)

  • Created by: Flo
  • Created on: 03-06-12 16:06

What is Phenology?

Phenology is how animals and plants change over seasons;

e.g. when buds first appear, when flowers emerge, when insects first appear, when animals come out of hibernation (come out of)

Records go back over 100’s of years so trends can be looked at.

Species - An individual belonging to a group of organisms (or the entire group itself) having common characteristics and (usually) are capable of mating with one another to produce fertile offspring.

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Darwin’s Theory of Natural Selection

Individuals in a population vary due to random mutations. Some of these random mutations may give individuals an advantage. This advantage may make individuals better adapted to survive. Therefore they are more likely to breed and pass on this advantage to the next generation. This is natural selection which leads to evolution.  

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Evidence for evolution

Darwin a Beak shapes of Galapagos Finches, Galapagos Sea lizards, and pigeons breeds, also studied fossil records. At that time genetics were not known about.

 Molecular evidence à 1953 DNA structure was discovered, study genetics (genomics),  study proteins (Protenomics)

DNA Hydridisation àDNA complementary bases A-T C-G, H2 bonds between bases broken of DNA from chimp and human, DNA strands allowed to anneal/stick back together, The more bases that are complementary between the species the more each strand will stick together. Therefore the more similar the species are.

 DNA profiling à DNA fragments ran through electrophoresis gel to compare similarities

 DNA Molecular Clocks à look at the number of random mutations in a species DNA, more mutations the longer the species has been evolving.

-          Evolution observed:

o   HIV exposed to new drug à  within days resistant strains have evolved.

o   Eastern US coast Asian Shore Crab introduced & eats Blue Mussels by cracking open shells. à Within 15 years the Blue Mussels have evolved thicker shells. 

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