Evolution Flashcards
Why have changes occurred to life on Earth?
As a result of natural processes.
What is the origin of life?
The origin of life on Earth is still unknown.
What does evidence support?
Evidence supports the presence of organic
molecules in space, based on examination of
comets/meteorites.
What suggests a possible location for the origin of single-celled organisms?
Observations of primitive life forms near volcanoes
and deep ocean hydrothermal vents
What did scientists discover about Earth’s early atmosphere?
there was no oxygen in the early Earth’s atmosphere by studying rocks
What is the source of oxygen?
cyanobacteria
How did scientists identify the source of oxygen; cyanobacteria?
Analysis and understanding of photosynthesis
helped identify cyanobacteria as the source of
oxygen.
What is a unifying hypothesis in the life sciences?
connection between these primitive prokaryotic
cells and all of the diverse forms of life that
followed.
Who developed a theory about evolution?
Darwin. A similar theory was also independently
developed by Alfred Wallace.
What did Darwin successfully do?
connected previously unrelated ideas into a coherent view of life
What does Darwin’s theory suggest?
The theory explains how increased reproductive success of individuals with favourable heritable characteristics can lead to change in the genetic composition of a population.
What is Darwin’s theory based on?
inferences based on observations.
How is evolution measured?
Although natural selection involves interactions
between organisms and their environment evolution is
measured by the changes in populations.
Why study natural selection?
increase understanding of the relationship between selective environmental pressures and survival of different organisms.
What was Darwin’s evidence based on?
geographical distribution of species and the fossil
record
What has led to new interpretations of the fossil record and a more complete picture of early animal evolution?
Continuing research and the development of
improved technologies
Does artificial selection occur to natural ecosystems?
No
What does artificial selection provide evidence for in terms of ecosystems?
species can change over time with selective
breeding
How does modern molecular biology support evolution?
by comparing the DNA and proteins of current and
ancestral species.
Why is there uncertainty about the ancestry of humans?
partly to incomplete fossil record and
misinterpretation of existing remains
What established a bipedal ape and when?
Radioactive dating has established the existence of
a bipedal ape in Africa 4.4 million years ago
What contributes to natural selection?
Development of tool making, hunting skills and
language
Where is the original source of human migration?
Rift valley of Central Africa.
What is the evidence for where the original source of human migration comes from?
evidence from mitochondrial DNA (mtDNA) and
Y chromosome
What led to the reclassification of Neanderthal man as Homo sapiens neanderthalensis?
A newly mapped Neanderthal genome provided
evidence of some interbreeding between modern
man and Neanderthal man
How have modern humans have demonstrated rapid cultural evolution?
minimal biological evolution.
What are genes?
special sequences of A, T, G and C’s in DNA that encode for proteins. Each gene is unique whose protein does a unique job
What is in the cell nucleus? (Think of a library)
Cell nucleus - library
Chromosomes - books (often come in pairs)
Genes - sentences (are found in chromosomes)
DNA - letters
Why is there variation in living organisms?
due to variation in the sequence of A, T, G and C’s in the genes inherited from the parents
Why is a mutation in a gene called?
alleles
When do mutations occur?
Inherited from parents or when the DNA is replicated before a cell divides into two
What are two types of mutagen?
- ionising radiation (ultraviolet light, gamma rays)
- chemicals (found in cigarette smoke, burnt food)
How are mutations corrected?
By DNA repair enzymes
What is the basis of natural selection?
- environment is changing
- variation can influence whether organisms are reproductively successful in certain environments
- if successful, the organisms pass on their genes to the next generation
- that particular variety will be more prominent in the population
What is the result of natural selection?
change the variation in an organism’s genome that it becomes a new species
What does artificial selection prove?
species can change over time with selective breeding
What is geographical isolation?
areas can become geographically isolated (earthquakes, ice ages, continental drift, water levels rising) resulting in individuals within the same species being unable to interbreed
What is homologous anatomy?
underlying organisational similarities in species anatomy
Why were Darwin’s ideas criticised at first?
- went against accepted, prevalent views
- difficult to prove with time spans involved
- fossil record was incomplete to support darwin’s ideas
What are the problems with homologus anatomy?
some unrelated species have similar structures (bats and birds). These are called analogous structures and are an example of convergent evolution
What is a clade?
grouping that includes a common ancestor and all the descendants (living or extinct) of that ancestor
What is endosymbiosis?
a relationship between two organisms where one lives inside the cell
What is mitochondria?
organelles found in cells, thought to have originated from bacteria living endosymbiotically in cells
What do mitochondria do?
Aerobic respiration
Where does the spine attach to the skull on bipedal apes?
In the centre of the head
When and how was the first human like ancestor
Radio-dating fossils, 4.4 million years ago
