CB4 Flashcards
Define ‘Species’?
A group of organisms that can reproduce with one another, producing fertile offspring.
Define ‘Evolution’?
A gradual change in the characteristics of a species over time.
How do fossils form?
They form when a living organism dies and overtime they start to be buried under sediment. As time passes, they get buried under more sediment and they get compressed, forming a fossilized version of themselves.
Give two pieces of fossilized evidence that proves that humans have evolved over time?
- Humans skull volume has increased over time, which shows evolution as humans brain capacity has increased over time when humans have became smarter.
- Humans spines have become stronger and more upright to support the upper half of humans body, which shows evolution as over time humans have gone from using their hands to support them to only using two legs.
What were stone tools used for?
- As weapons against other humans
- To skin animals
- To cut up meat
How have stone tools developed over time?
Over time, stone tools have become sharper.
How can stone tools be used to determine evolution?
- Shows that the human brain evolved enough to realize that they need sharp tools for hunting.
- Stone tools getting bigger and sharper showed that humans were getting smarter as they were finding more ways to make stone tools sharper.
- The tools have become more sophisticated which makes them able to carry out more accurate and detailed work.
Explain Darwin’s theory of evolution?
- It starts with ‘competition’, which is the demand by organisms for limited environmental resources (such as food, water etc.)
- After this is ‘adaptation’, which is where characteristics are inherited (such as longer beaks to reach prey underground)
What is Darwin’s theory called?
Natural Selection.
Summarise the evidence for evolution?
- Stone tools (predicting when humans were able to start using their hands)
- The fossil record (shows which fossils are produced when and shows evolution throughout the years)
- DNA (can identify DNA of ancestors to find out the related genes)
What is some evidence against evolution?
The fossil record is missing millions of years of evolution which can mean that the evidence for evolution is incorrect.
What does ‘Survival of the fittest’ mean?
It means that only those that are the most adapted to their surroundings will survive. This means that survival is only guaranteed to those who have evolved to have characteristics to fit their surroundings.
What happens if an animal is not well adapted or ‘fit’?
They will die if the are not able to reproduce, resulting in the species going extinct (e.g. Dodo Bird, Woolly Mammoth, Sabre-Toothed Cat)
Define ‘Common ancestor’?
An ancestor that two or more descendants have in common.
How did rats avoid extinction?
In the 1940-50’s, warfarin was being used to kill rats. When it was first used, most rats died, but within 10 years most rats were resistant to warfarin. Due to genetic variation there had always been some rats that were resistant. As the poison killed the non-resistant rats, the only ones left to breed to make the offspring of those rats resistant to warfarin, avoiding extinction.
Define ‘Classification’?
The process of sorting organisms into groups based on their characteristics.
Name the 5 kingdom method of classification
- Animals
- Plants
- Fungi
- Protists
- Prokaryotes
What is the order of classification from biggest to smallest?
- Kingdom
- Phyllum
- Class
- Order
- Family
- Genus
- Species
What are the main characteristics of the animal kingdom?
Multicellular (with cells arranged as tissues and organs), Cells have nuclei, No cell walls
What are the main characteristics of the plant kingdom?
Multicellular (with cells arranged as tissues and organs), Have chloroplasts for photosynthesis, Cells have nuclei, Cellulose cell walls
What are the main characteristics of the fungi kingdom?
Multicellular (apart from yeasts), Live in or on the dead matter on which they feed, Cells have nuclei, Cell walls contain chitin (not cellulose)
What are the main characteristics of the protists kingdom?
Mostly unicellular (a few are multicellular), Cells have nuclei, Some have cell walls (made of different substances but not chitin)
What are the main characteristics of the prokaryotes kingdom?
Unicellular, Cells do not have nuclei, Flexible cell walls
How has classification changed over time?
Scientists decided to switch from the five kingdom system of classification to the three domain system of classification, which includes Bacteria, Archaea and Eukarya.
What is the Archaea domain?
Cells with no nucleus, genes contain unused sections of DNA.
What is the Bacteria domain?
Cells with no nucleus, no unused sections in genes.
What is the Eukarya domain?
Cells with a nucleus, unused sections in genes.
What is Artificial Selection?
When humans choose certain organisms with certain characteristics (as they have useful characteristics) and use only those ones for breeding.
What is Selective Breeding?
When humans choose an organism that has a certain characteristic and breed more of these organisms, making that chosen characteristic more and more obvious.
Why is Selective Breeding used?
- To produce new breeds of animal species.
- To produce new varieties of plant species.
Define ‘Breeds’?
A group of animals of the same species that have characteristics that make them different to other members of the species.
What reasons are plants selectively bred for?
- Disease resistance
- Yield
- Coping with environmental conditions
- Fast growth
- Flavour
What is genetic engineering/genetic modification?
Changing the DNA of one organism by inserting genes from another organism, which creates genetically modified organisms (GMO’s)
What are two differences between Artificial selection and Genetic Engineering?
- Genetic Engineering is much faster than Artificial Selection.
- Artificial Selection is a much cheaper process than Genetic Engineering.
What are genetically modified bacteria useful for?
They can be used as Antibiotics and other medicines (e.g. Insulin)
What are some issues of Selective Breeding?
- Lack of genetic diversity
- Genetic mutations will still occur
What are some issues of Genetic Modification?
- It is very expensive
- Some people believe that eating GM organisms are bad for people’s health (though there is a lack of evidence supporting this)
What is a vector?
A DNA molecule that is used to carry new DNA into another cell.
What are plasmids?
A small loop of DNA found in the cytoplasm of bacteria.
What are restriction enzymes?
An enzyme that cuts DNA molecules into pieces.
How is bacteria genetically engineered to produce lots of insulin?
- Restriction enzymes make staggered cuts in DNA molecules, producing sections with a few unpaired bases at each end. A section of DNA containing the gene for making insulin is cut from a human chromosome in this way.
- Restriction enzymes are also used to cut plasmids open. By using the same restriction enzyme that was used on the human chromosome DNA, the cut plasmids have the same unpaired bases on each end.
- Sections of DNA containing the insulin gene are mixed with the cut plasmids. The complementary bases on each end pair up. An enzyme called ligase is used to join the ends together.
- The plasmids are then inserted back into bacteria, which make them then grown in huge tanks. The insulin they make can now be easily extracted.
Define ‘Recombinant DNA’?
DNA made by joining two sections of DNA together.
What is Ligase?
A type of enzyme used to join base pairs together.
What are some advantages of Selective Breeding?
- New plants and animal varieties can be created.
- Future generations are guaranteed to maintain mutations.
What are some advantages of Genetic Modification?
- Fast process
- Resistant to genetic diseases
