Year 11 Chapters 13-17 Flashcards
Define variation…
Differences in the characteristics of individuals in a population.
What causes variation within a population?
- The genes they have inherited (genetic cause).
- The conditions in which they have been developed (environmental cause).
Define evolution and define a species…
- A change in the inherited characteristics of a population over time through a process of natural selection, which may result in the formation of a new species.
- A group of similar organisms capable of interbreeding to produce fertile offspring.
Define selective breeding…
The process by which humans breed plants and animals for particular genetic characteristics.
What are the steps to selective breeding?
1) Choose two parents with the desired characteristics from a mixed population.
2) Breed the two parents together to produce offspring.
3) From the offspring, choose those with the desired characteristic a d breed them together.
4) Repeat the process over many generations until all the offspring show the desired characteristic.
List some of the advantages of selective breeding:
- Can produce animals/plants with desirable characteristics, which can yield increased profits.
- Can create new varieties of crops/animals.
- Disease resistance in crops or harden plants.
- Can produce domesticated animals with a gentle nature (e.g: the labradoodle).
List some of the disadvantages of selective breeding:
- Inbreeding of plants/animals can increase genetic defects in small gene pools.
- Selective breeding can be expensive (e.g: breeding someone else’s fast racehorse with yours to produce a faster one).
- Ethical and moral issues (forcing animals to breed - controlling nature).
- Reduces variation (which reduces how much a species can adapt to changes in an environment).
Give a named example of the danger’s of inbreeding:
The boxer dog has an increased risk of epilepsy because of genetic defects that have been passed on through generations of inbreeding, with a lack of variation being the cause for the genetic defect to develop.
What is natural selection?
Natural selection is the idea that because plants and animals are constantly competing, organisms with an advantage are more likely to survive, breed and pass on their alleles that gave them an advantage. As a result, the offspring will have an advantage and continue to survive and breed, with the selection of the desirable characteristic that helps them survive being natural.
Give a named example of natural selection:
In 1915, oyster beds in Canada were almost wiped out because of a disease but some oysters had a resistance to this disease and were resultantly the only survivors. After this, more oysters were appearing because the disease could no longer affect the new immune generation, which had the alleles of the previous generations survivors.
What is the difference between genetic and environmental variation?
Genetic variation is the difference in the alleles of genes between individuals within a population whilst environmental variation is the difference in the area that two individuals are from.
Give examples of factors that are controlled by genetics, environment or both:
- Factors such as gender, eye colour and natural hair colour are controlled by your genetics.
- Factors such as your religion, your language and your hair length are controlled by your environment.
- Factors such as your skin colour, your weight and your height are controlled by a mixture of these two.
Who is Charles Darwin and why is he significant?
Charles Darwin is the man who created the theory of evolution and, though he admitted it had its flaws, he was strongly criticised for this by zealots as it was seen as a heresy to the Christianity (as they believed God made them as humans, as they are now).
What are the steps to genetic engineering?
- Enzymes are used to isolate the required gene.
- This gene is then cut out and inserted into a vector (usually a bacterial plasmid or virus).
- The vector is used to insert the gene into the required organism (host).
- Genes are transferred to cells of animals/plants/micro-organisms at an early stage in their development so that they can develop the desired characteristics.
Why would people genetically engineer (advantages)?
- Improve crop yields.
- Increase resistance to pesticides.
- Extended shelf-life for food.
- Manufacture certain chemical.
Why shouldn’t you genetically engineer (disadvantages)?
- Inserted genes may have unwanted side effects.
- Genetically modified (GM) animals might escape and/or breed with wild animals
What is a fossil?
Fossils are the ‘remains’ of organisms from millions of years ago which are found in rock.
How are fossils formed?
- Organisms are covered un sediment/mud or sink into the mud.
- Softer parts decay/are eaten.
- Bones/harder parts do not decay.
- Minerals enter the bines and they are preserved.
- Layers of sediment get compressed over time, forming sedimentary rock.
- Conditions for decay may be absent (e.g: no oxygen).
Define speciation…
Speciation is the formation of a new species due to evolution (may cause extinction of related species, e.g: early hominids are now extinct (early humans).).
What causes mutation?
Mutation is caused by the need for adaptation to better survive in a specific environment or climate.
What creates antibiotic resistant bacteria?
- A single cell of antibiotic resistant bacteria is produced through mutations.
- Antibiotics kill all non-resistant bacteria, leaving the single resistant strain.
- Resistant bacteria divides to produce an entire population of antibiotic resistant bacteria.
