P1B4 - Natural selection + Genetic modification Flashcards
What is evolution?
A change in one or more characteristics of a population over a long period of time
How do scientists date/age fossils
Depths of fossil in layers of sedimentary rock (closer=recent)
Stone tools (detail=recent)
Closely related species have the same genes in their binomial name
What is the binomial system?
Kingdom
Phylum
Class
Order
Family
Genus
Species
Who is Carl Linnaeus? (1707 - 1778)
He suggested humans evolved from apes, developing the binomial system
What is closely related to Homo sapiens?
Ardi - 4.4 mil years old
Lucy - 3.2 mil years old
Homo habiliis - 2.4-1.4 mil years old
Homo erectus - 1.8-0.5 mil years old
The trends in human evolution?
Increasing brain volume
Increasing height
Decreasing hair
Decreasing arm length to body ratio
What plays a part in natural selection?
Genetic variation
Survival of the fittest
Successful breeding
Best characteristics survive
How do stone tools provide evidence for human evolution?
Old stone tools are simple and were used for cutting meat, recent tools are more sophisticated and shaped for specific functions .
Thus, humans evolved to become smarter and more able to use their hands
Why do some bacteria become resistant to antibiotics?
Natural selection neatly explains this phenomenon:
Bacteria reproduce rapidly.
Mutations occur during reproduction.
If a mutated bacterium is resistant to antibiotics, it will survive exposure to antibiotics and go on to reproduce.
This bacterium will represent the original ancestor of a new resistant strain.
What 3 domains did Carl Woese propose?
Archaea - primitive bacteria. (Unused DNA)
Bacteria - true bacteria. (All DNA used)
Eukaryota - organisms possessing complex sub-cellular structures (protists, fungi, plants & animals). (Unused DNA)
What is tissue culturing?
Growing genetically identical cells in a lab under sterile conditions (without contamination from microorganisms).
Growing cells or tissues in a liquid containing nutrients or using agar.
How do we prepare an uncontaminated bacterial culture using aseptic techniques?
- Sterilise equipment/culture with an autoclave (applies heat under pressure to kill pathogens). Disinfect surfaces and create a convection current using bunsen.
- Sterilise inoculating look by passing it through bunsen.
- Remove culture lid and flame rim of bottle before and after bacteria collection.
- NO equipment should be PUT DOWN during the process!
- Spread bacteria on agar by lifiting petri dish SLIGHTLY, gently spreading loop across surface of agar.
- Seal dish with tape and store upside down at 25C (To prevent harmful bacteria from gorwing) for 48 hours.
Why is Selective breeding in crops useful?
Disease resistant crops improves yield (food production productivity).
Why is selective breeding in animals useful?
In farming, animals that produce more milk or meat are also useful for yield-related reasons
What are some dangers of selective breeding?
Reduced variation
Inbreeding - some breeds become particularly susceptible to disease or inherited defects.