B6: Variation and evolution Flashcards
(22 cards)
What is variation?
All the differences in the characteristics of individuals in a population
What are the causes of variation? (3)
- alleles that individuals have inherited (genetic factor)
- environment
- combination of genes and environment (eg. height)
What can lead to a new phenotype being created?
A mutation
What is evolution?
The change in the inherited characteristics of a population over time through a process of natural selection
How does evolution take place through natural selection?
If the environment changes, then animals with certain characteristics will be more likely to survive and pass on their characteristics. This leads to changes in the population over many generations.
What is selective breeding?
When humans breed plants and animals for particular genetic characteristics.
What are the disadvantages of selective breeding?
Inbreeding, which can mean they are more likely to develop inherited disorders.
Give four specific examples of selective breeding?
- dogs = gentle nature
- food crops = disease resistance
- cows = more meat / milk
- plants = large/ unusual flowers
Describe the stages of selective breeding
- Find a male and female with the desired features and breed them together
- Take the male and female offspring with the best characteristics and breed them together.
- Continue doing this over many generations until the whole population have to desired characteristics.
What is genetic engineering?
Modifying the genome of an organism by introducing a gene from another organism to result in a desired characteristic.
How is genetic engineering carried out?
- Identify the gene you want to transfer
- use enzymes to isolate the gene
- transfer the gene into a small cell of DNA called a plasmid (which originally came from bacteria) OR use a virus. These are vectors
- the gene is transferred into the cells of the target organism.
- We always do this early on in development, to make sure all the cells develop with the transferred gene.
How is genetic engineering used in medicine and agriculture?
- used to make bacteria produce insulin to treat type 1 diabetes
- used to make GM crops, which usually have a higher yield or can be resistant to pesticides or disease.
Describe how fossils provide evidence for evolution
We can see evidence other organisms existed and changed over time
How are fossils formed?
- when parts of organisms have not decayed (eg. too cold, not enough oxygen…)
- parts of the organisms are replaced by minerals during the decay process
- preserved traces of organisms (eg. footprints)
Why are there very few fossils for early life forms?
They were soft bodied organisms, which rarely form fossils
The ones that do survive have been destroyed by changes to rocks in the earth’s crust
How can species become extinct?
- catastrophic event
- environment changes
- new more successful species evolves and competes with it.
What is a fossil?
Remains of organisms from millions of years ago which are found in rocks
How do bacteria become resistant to antibiotics?
- A mutation makes a bacterium resistant to antibiotics
- We use antibiotics, and all the other bacteria die
- the antibiotic strain survives and reproduces without any other competition from other bacteria, and the population rises
- the strain spreads.
How can we reduce the rate of development of resistant bacteria? (3)
- Don’t prescribe antibiotics inappropriately (eg. to treat a virus)
- Make sure they complete their course of antibiotics, even if they start feeling better
- Restrict the use in farming
Describe Linneaus’ classification system:
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Kids Play Cricket On Flat Green Surfaces
What is the three domain classification system?
- the current classification system which is more modern
- Archae: primitive bacteria, found in extreme conditions
- True Bacteria
- Eukaryota: animals, plants, fungi, protists
What is the binomial naming system?
Naming an animal after their genus and species
