Topic 4: Natural Selection and Genetic Modification Flashcards
(48 cards)
What are the steps of natural selection?
Variation, Selection pressure, Survival of better adapted, Reproduction, Passing on alleles
What is variation?
Differences in characteristics within a species, often caused by mutations or genetic inheritance
What is a selection pressure?
An environmental factor that affects an organism’s chances of survival and reproduction
What does ‘survival of the fittest’ mean?
Organisms best adapted to their environment are more likely to survive and reproduce
What is evolution?
Gradual change in inherited traits of a population over time
How is antibiotic resistance in bacteria evidence for evolution?
Random mutations make some bacteria resistant; they survive, reproduce and pass on the resistance
Why must we finish a course of antibiotics?
To kill all bacteria, including partly-resistant ones, reducing chance of resistant strains surviving
What happens if a course of antibiotics is not completed?
Partially resistant bacteria may survive, reproduce and spread resistance
What is a fossil?
Preserved remains or traces of ancient organisms, found in sedimentary rock
How are fossils evidence for evolution?
They show gradual changes in organisms over time
Who proposed the theory of natural selection?
Charles Darwin and Alfred Russel Wallace
What book did Darwin write?
On the Origin of Species
Who was Ardi?
Ardipithecus ramidus, 4.4 million years ago, long arms, short legs, brain size ~350cm³, tree and ground movement
Who was Lucy?
Australopithecus afarensis, 3.2 million years ago, arms shorter than Ardi, more upright, brain ~400cm³
Who was Turkana Boy?
Homo erectus, 1.6 million years ago, modern body, short arms, long legs, brain ~700cm³
What does the human fossil record suggest?
Humans evolved from apes, becoming more upright with increasing brain size
What is the order of human evolution?
Ardipithecus → Australopithecus → Homo species
What do stone tools show about evolution?
Increased tool complexity over time indicates increased intelligence
What is carbon dating?
A method to date dead organic material by measuring radioactive carbon-14 decay
What is stratigraphy?
Dating fossils based on the layer of rock they’re found in; deeper = older
What is the pentadactyl limb?
A limb with five digits, found in many vertebrates like humans, bats, and whales
How is the pentadactyl limb evidence for evolution?
Shows common ancestry due to shared limb structure across species
Why was classification changed to use domains?
Advanced genetic analysis showed fundamental differences between types of prokaryotes
What is DNA sequencing?
Identifying the exact order of bases in DNA to compare genetic material
