Natural Selection & Evolution Flashcards
All 15 cards in this deck
What are the steps of Darwin's theory of evolution by natural selection?
e.g. mice living on dark soil becoming darker over time
- Variation from mutation: some mice are born darker.
- Selection pressure (predators) — dark mice are camouflaged, so they are more likely to survive and reproduce.
- They pass the allele to their offspring; over many generations more of the population is dark.
What are the steps by which bacteria become resistant to an antibiotic?
e.g. bacteria becoming resistant to colistin
- A random mutation gives some bacteria a gene/allele for resistance.
- The antibiotic acts as a selection pressure (overuse, or the course not finished): non-resistant bacteria are killed, resistant ones survive.
- The resistant bacteria reproduce and pass on the resistance; the process repeats, so resistance spreads.
True or false? Bacteria mutate in order to become resistant when an antibiotic is used.
False. Mutations happen randomly; the antibiotic simply selects the bacteria that are already resistant (they are resistant, not 'immune').
How long ago did the hominid fossil 'Ardi' live?
4.4 million years ago. Her long arms and grasping feet suggest she climbed trees but could also walk upright.
How long ago did the hominid fossil 'Lucy' live?
3.2 million years ago. Her arched feet and pelvis show she was fully bipedal, with a brain slightly larger than Ardi's.
How old are the hominid fossils discovered by Richard Leakey's team, and what did they show?
1.6 million years old, with a much larger brain/skull, shorter arms and longer legs — more human-like than Lucy.
Give two structural changes shown by fossilised bones during human evolution.
Larger skull / larger brain, and bipedalism (walking upright).
What are the steps to date a stone tool from the environment it was found in?
e.g. a tool dug out of a deep rock layer
- Record the position/depth of the tool in the rock layers (stratigraphy) — the deeper layer means an older tool.
- Date other fossils found in the same layer.
- Use radiometric dating of the rock layer to give an age.
What feature of a stone tool suggests it was used by a more recent human ancestor?
It is more sophisticated — more shaped, carved, complex or sharper.
Name the three domains in the three-domain classification system.
Archaea, Bacteria and Eukarya.
Give one reason why the three-domain classification system was proposed instead of the five kingdoms.
Genetic analysis (comparing DNA/RNA) showed the DNA of archaea is more similar to that of eukaryotes than to bacteria.
True or false? Using antibiotics to treat a viral infection can contribute to the development of antibiotic resistance.
True. It is inappropriate use that exposes bacteria to the antibiotic, acting as a selection pressure.
Give two examples of selection pressures.
Any two: predation, disease, and competition for resources such as food, water or mates.
Which kingdom did Carl Woese's genetic analysis split into two separate domains?
The prokaryotes, which he split into Archaea and Bacteria because their genetic sequences are very different.
Which types of organism are in the domain Eukarya?
Animals, plants, fungi and protists (all organisms whose cells have a nucleus).