CB4: Natural Selection and Genetic Modification Flashcards
Define Evolution
the gradual change in the characteristics of a species over time
What is a fossil?
Preserved remains of a dead organism which help scientists to find out more about human evolution
Name the four main fossils we use to prove evolution
- Ardi (Ardipithecus ramidus)
- Lucy (Australopithecus afarensis)
- Homo habilis
- Homo erectus
Describe Ardi
- may have been able to walk upright but had grasping big toes which allowed her to climb trees
Describe Homo habilis
feet adapted to walking upright - feet like ours, becoming smaller, arms shorter
Describe Homo erectus
- body structure adapted to walking and running
- feet getting smaller and spines getting straighter
How are tools used as evidence for human evolution?
Scientists can work out the ages of the layer of rocks the tools are found in and they assume that the layer of rock and the tool are the same age
How do tools show evolution of humans?
The oldest stone tools are the simplest whereas the newer ones are more sophisticated, showing that as species progressed, their work became more sophisticated and they became much smarter
Who came up with the ideas about evolution?
Charles Darwin
State and explain what the acronym GENIE stands for
Genetic variation: the characteristics of individuals vary due to genetic variation + mutations
Environmental change: conditions in an area change which results in competition among organisms
Natural Selection: those better adapted to said environmental change survive…
Inheritance: and reproduce, which results in their offspring inheriting their favourable genes
Evolution: if the environmental conditions remain changed, natural selection occurs over and over again, and a new species evolves with all the individuals having ‘better adapted variations’
What are evolutionary trees?
Charts that show common ancestors between species
Define resistance
How protected something is against another thing
Why were Darwin’s ideas rejected at the time?
- contradicted the idea that God was the creator of all species on Earth
- not enough evidence at the time as few studies had been done on how organisms change over time
- the mechanism of inheritance and variation weren’t known at the time
Describe the process of antibiotic resistance
- Bacteria in a population show variation in the amount of resistance toward a certain antibiotic
- Course of antibiotics begins
- With time, the antibiotic kills more and more bacteria. The most resistant bacteria take the longest to die
- As a result, the bacteria can pass on the advantageous gene to their offspring, creating a whole new strain of resistant bacteria
Describe the classification system created by Carl Linnaeus
Living organisms are classified into groups depending on their structure and characteristics
What are the five kingdoms?
- Plants
- Animals
- Protists
- Fungi
- Prokaryotes
Name all of the categories in the classification system
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
What mnemonic is used to remember the classification system?
Dear King Phillip Came Over From Germany Singing
Describe the main characteristics of the Kingdom Animals
- multicellular
- cells have nuclei
- no cell walls
Describe the main characteristics of the Kingdom of Plants
- multicellular
- cells have nuclei + chloroplasts
- cellulose cell walls
Describe the main characteristics of the Kingdom Fungi
- multicellular except yeasts
- cells have nuclei
- chitin cell walls
- feed off dead matter
Describe the main characteristics of the Kingdom Protists
- mostly unicellular
- cells have nuclei
- some have cell walls (not chitin)
What is the binomial naming system and how is it written?
- based on the genus and the species
- genus has a capital letter and the rest of the two words are lowercase and in italics
What is the three domain system?
Developments in science found that some species had more in common than originally thought. Therefore, in the 1970s, scientist Carl Woese added three larger groups over the kingdoms called ‘domain’. These were
- bacteria
- eukarya
- archaea
Describe the organisms in the three domain system
- Archaea: primitive bacteria which live in extreme conditions such as hot springs (no nucleus, unused sections of DNA)
- Eukarya: organisms who have a nucleus enclosed in membranes, including the kingdoms protists, fungi, plants, and animals (nucleus, unused sections of DNA)
- Bacteria: true bacteria (no nucleus, no unused sections of DNA)
Describe the main characteristics of the Kingdom Prokaryotes
- unicellular
- flexible cell wall
- no nucleus
What is genetic modification?
The process of moving a gene or several genes from one species to another
What is selective breeding?
When humans choose which offspring to breed in order to produce a certain desirable characteristic
What can selective breeding lead to?
It can lead to inbreeding which leads to a reduction in the gene pool
Why is inbreeding dangerous?
If the environment changes, or if one of the individuals caught a disease the species isn’t resistant against, it could become extinct as they all have the same genetic makeup.
Another problem is that it leads to a greater chance of genetic defects in the offspring as recessive characteristics are more likely to be present
Furthermore, alleles that could be useful to us in the future are lost
Give two examples of genetic engineering
- Plants GE ed to produce a higher yield
- Bacteria GE ed to produce substances useful to humans eg: insulin for diabetes
Describe the process of genetic engineering a bacteria to produce insulin
- Plasmid DNA is removed from a bacterium
- Plasmid DNA is cut open using restriction enzymes, leaving behind sticky ends
- DNA removed from the cell nucleus
- The gene that gives the desired protein is cut from the same restriction enzyme as the plasmid to leave complementary sticky ends on both sides
- Ligase enzyme is used to ensure plasmid DNA and human DNA attach by forming complementary base pairs, creating a new loop of plasmid (recombinant DNA)
- The recombinant DNA is put back into bacteria which divide rapidly, producing the required protein, which is then extracted
Describe the process of selective breeding
- Parents with desired characteristics are chosen
- They are bred together
- From the offspring, those displaying the most of the desired characteristics are bred together
- The process is repeated multiple times until all the offspring have the desired characteristic
What are the advantages of genetic engineering?
- crops are made resistant to diseases
- faster than selective breeding
- no evidence of harm to health
- insulin suitable for everyone can be made
What are the disadvantages of genetic engineering?
- process and GM seeds are expensive
- GM crops may reproduce with wild plants
What was the skull volume of Ardi?
350 cm cubed
How many years does Ardi date back?
4.4 million years
How many years does Lucy date back?
3.2 million years ago
What is the skull volume of Homo Habilis?
500-600 cm cubed
How far does homo habilis date back?
2.4-1.4 million years
How much skull volume did homo erectus have?
850 cm cubed
How many years did homo erectus date back?
195,000
