Topic 4 (Natural Selection And Evolution) Flashcards
What is natural selection?
Individuals in a population show genetic variation due to differences in their alleles, predation, competition for resources and disease act as selection pressures.
Which affects the organisms chance of surviving and reproducing.
Individuals with characteristics better adapted to the selection pressures have a better chance of survival and more likely to breed successfully.
the alleles which useful characteristics are passed onto the next generation.
Some individuals will be less adapted so less able to compete and less likely to survive and reproduce.
Overtime, the beneficial characteristics become more common.
Why does bacteria provide evidence for evolution?
Antibiotic resistance - antibiotics are given for illnesses, bacteria can develop random mutations in their DNA - change characteristics = bacteria less affected by antibiotic.
Antibiotic kills most but the mutated bacteria survives, and forms a new colony which have the gene for antibiotic resistant. Different antibiotic will have to be given, but resistance can still develop.
The problems of antibiotic resistance
-Doctors often give out antibiotics where they won’t work or in non serious cases.
-Farming - antibiotics in the food of healthy animals, to prevent becoming ill, and grow faster.
-Scientists are trying to develop new antibiotics that work against the resistance strain - difficult, slow
How do fossils provide evidence that organisms evolved from simpler life forms?
-Arrange fossils in chronological order to show the gradual change in organisms. Most common in rocks.
-The deeper the rock the older the fossil.
-Fossil provide evidence for human evolution.
Who wrote the theory of evolution by natural selection?
Charles Darwin
Evolution influence on modern biology
- Classification - if all living organisms have descended from a common ancestor then they are related in someway.
-Antibiotic resistance
Conservation - importance of genetic diversity and it helps populations adapt to changing environments which has led the conservation project to protect species.
What is hominids?
Human beings and their different ancestors. By looking at hominid fossils you can see how humans have evolved over time.
What was Ardi?
- 4.4 million years old.
-Her feet suggests she climbed trees - she had an ape-like big toe.
-Had long arms and short legs.
-Brain size was same as a chimpanzee’s. - Leg structure suggests walking upright, hand bone suggests she didn’t use her hands.
What was Lucy?
-3.2 million years old.
-Had arched feet - walking more than climbing.
-Size of legs and arms between apes and human.
-Brain slightly larger; still similar to a chimps brain.
-Leg bones and feet suggests she walked upright.
What was Leakey? Turkana Boy
-1.6 million years old.
-More human like than Lucy.
-Short arms and long legs, brain size much larger than Lucy’s.
-Legs and feet better adapted to walking upright.
Outline the major changes observed between the fossils of Ardi and Lucy and the fossils recorded of hominids
Lucy’s feet were more arched than Ardi’s. Lucy’s arms and legs were more human like than Ardi’s. Lucy had a bigger brain than Ardi. The structure of Lucy’s leg bones and feet suggest she was more efficient at walking upright than Ardi.
What tool did Homo habilis use?
(2.5 - 1.5 million years ago) Made simple stone tools called pebble tools by hitting rocks together to make sharp flakes. Can be used to scrape meat from bones or crack bones open.
What tool did Homo erectus use?
(2 - 0.3 million years ago) sculpted rocks into shapes to produce more complex tools like simple hand- axes. Could be used to hunt, dig, chop and scrape meat from bones.
What tool did Homo neanderthalensis use?
300000 - 25000 years ago. More complex tools. Evidence of flint tools, pointed tools and wooden spears.
What tool did Homo sapiens use?
200000 years ago. Flint tools widely used. Pointed tools including arrowhead, fish hooks and needles appeared around 50000 years ago.
