Topic 4 - Natural Selection and Genetic Modification Flashcards
In simple terms, what does natural selection mean?
‘Survival of the Fittest’
What 3 things act as selection pressures:
- Predation
- Competition
- Disease
How do bacteria provide evidence for natural selection?
- Bacteria have different levels of resistance to antibiotics
- Antibiotics wipe out low-resistance bacteria
- High-resistance bacteria reproduce
- All bacteria are now resistant to the antibiotic
What is a fossil?
Any trace of an animal or plant that lived a long time ago
How do fossils provide evidence for evolution?
- Fossils from long ago are deeper in the ground
- Fossils can be placed in chronological order
- Changes can be seen in the fossils over time, which is evolution of the species
What did Darwin come up with?
The theory of Evolution by Natural Selection
How did Darwin come up with the idea of Evolution?
- He spent 5 years on a voyage around the world
- He saw variations between organisms of the same species
- He predicted that these variations would help the organisms to survive longer through environmental changes
How did Wallace contribute to the theory of Evolution?
- Studied organisms separately to Darwin
- Saw differences with butterflies (warning colours)
List the human ancestors in order from oldest to newest:
- Ardipithecus Ramidus (Ardi)
- Australopithecus Afarensis (Lucy)
- Homo Erectus (Turkana Boy)
- Homo Sapiens (MODERN DAY HUMANS!)
Other than fossils, what evidence is there for evolution?
Tools - As humans have developed, the tools have become more sophisticated to suit our needs. For example, we made pointed rocks for hunting.
How can stone tools be dated?
They contain carbon, so can be carbon-dated using the isotope Carbon-14
What is a pentadactyl limb?
A limb with five ‘digits’ - e.g. a hand
How does the pentadactyl limb provide evidence for evolution?
Many species share a pentadactyl limb, and it is highly unlikely that we would all have this if we originated from different ancestors. Thus, all organisms with this limb are likely to have originated from a common ancestor.
What is classification?
The organisation of living organisms into groups
What are the five kingdoms?
- Animals
- Plants
- Fungi
- Prokaryotes (Single-celled without a nucleus)
- Protists (Eukaryotic single-celled)
What are the subsections that come after kingdoms?
- Phylum
- Class
- Order
- Family
- Genus
- Species
What is selective breeding?
When humans artificially select the plants or animals they are going to breed so that they can get desired genes/characteristics
Give 4 examples of why we selectively breed:
- Animals that produce more meat or milk
- Bigger fruit
- Crops with disease resistance
- Dogs that are better behaved
What are the 4 basic steps in selective breeding?
- Choose stock with the best characteristics
- Breed them together
- Select the best offspring, and breed them
- Repeat over several generations
What are the advantages of selective breeding?
- Yield in agriculture
- Medical purposes
What are the disadvantages of selective breeding?
- Lower gene pool
- INBREEDING
- High risk of diseases being passed on through generations
What is genetic engineering?
Modifying an organism’s genome to introduce desirable characteristics
How is a gene removed from an organism
By using restriction enzymes that cut out the gene and leave sticky ends
How is a cut gene put into a bacterium cell?
- Same restriction enzyme is used to cut into a plasmid DNA
- Gene and plasmid have matching sticky ends
- Ligase is added
- The gene fits into the plasmid, forming recombinant DNA
- This is then put back into the bacterium
Give one use of genetic engineering in medicine:
Genes such as insulin can be taken and put into a bacterium to produce lots of it, for people with diabetes to use
Give one use of genetic engineering in agriculture:
Increased yield - Crops become bigger and more resistant to diseases
How is genetic engineering crucial in terms of the increasing human population?
Increasing global food supply
- Fewer crops are impacted by diseases
- Crops are bigger, so feed more people
What is tissue culture?
The artificial growth of plants
What are the stages of tissue culture?
- Select plant to clone based on characteristics
- Remove several pieces of tissue
- Grow the tissue in a growth medium containing nutrients and growth hormones
- As the tissues produce roots and shoots, they can be put into soil
- Now, the plant can grow
Why is animal tissue culture good for medical research?
You can investigate the effect of substances on type of cells (and see what causes damage to them)
