Topic 4 - Natural Selection Flashcards
What is evolution?
A gradual change in the inherited traits within a population over time
Occurs due to natural selection
Outline the theory of natural selection
Genetic variation exists due to spontaneous mutations
Selection pressured exist
Random mutation gives an organism a selective advantage
Organism is better adapted to the environment and survives
Organism reproduces, passing on its beneficial alleles
Frequency of advantageous alleles increase
Why does competition between organism in a habitat exist?
The resources within a habitat requires for survival are limited
Describe how antibiotic resistance in bacteria can be used as an example to illustrate the process of evolution
Genetic variation exists due to spontaneous mutation
Antibiotics act as a selection pressure
Mutations gives a bacterium antibiotic-resistance
If an antibiotic is administered,the bacterium is better adapted and survives, whilst other bacteria are killed
Bacterium reproduces, passing on its resistant variant
Frequency of antibiotics-resistant allele increases
How can the observation of fossils provide evidence for evolution?
How has the theory of evolution by natural selection impacted modern biology and society
Enables the classification of organisms into taxa
Influences modern medicine by emphasising the importance of finishing antibiotics treatments and the need for constant production of new antibiotics.
Highlights the importance of high genetic diversity in habitats, which aids conservation projects.
What fossils have provide evidence for human evolution?
“Ardi’ - 4.4 million years old
“Lucy” - 3.2 million years old
Leakey discovered 1,6 million years ago
What clues does “ardi” gives scientists about human evolution?
Female hominid fossil. She shows phenotypic traits which encompass characteristics of both humans and apes.
Ape-like characteristic e,g long arms, large big toes
Human-like characteristic - structure of her bones suggest that she walked upright
What clues does “Lucy” gives scientists about human evolution?
How did leakey’s findings provide evidence for human evolution?
How has the development of stone tools provided evidence for evolution?
Correlation between the development of more complex tools and increase in brain size
Primitive tools are older than more complex tools. Brain size has increased over time, as brain size increases , advancements in tool use were made.
Describe the methods used by scientists to date tools
What is a pentadactyl limb?
A limb with five digits present in animals, bird, reptiles and amphibians
How does the pentadactyl limb provide evidence for evolution?
The presence of the pentadactyl limb suggests that all species which possess it have descended from a common ancestor.
What advancements in science have led scientists to reconsider the five kingdoms classification system?
Microscopes
Biochemistry
DNA and RNA analysis
Traditionally, organism were grouped bases on similarities and differences in their anatomy and behaviour. What is the problem with this?
Organisms that are not closely related may look alike and behave similarly if they live in the same environment e,g sharks and dolphins
Some closely related species may look very different if they live in different habitats e,g queen ants, worker ants
Describe the three domains systems
Organism are initially divided into an extra three groups:
Archaea, Bacteria, Eukarya
What is selective breeding?
The process by which humans artificially select organisms with desirable characters and breed them to produce offspring with similar phenotypes.
Outline the main steps involved in selective breeding
What is the main advantage of selective breeding?
Creates organisms with desirable features
Crops produce a higher yield of grain
Cows produce a greater supply of milk
Plants produce larger fruit
Domesticated animals
Other than in agriculture, where else is selective breeding useful?
In medical research
In sports e,g horse racing
Outline disadvantages of selective breeding
How can plants be clones
Taking plant cuttings
Tissue cultures
What is tissue cultures?w
A method of growing living tissues in a suitable medium
Describe how plants are grown using tissue culture
Select a plant that shows desired characteristics
Cut multiple small Sample pieces from meristem tissue
Grow in a Petri dish containing growth medium
Transfer to compost further growth
What must be ensured when preparing tissue cultures?
Ensure Aspetic conditions to prevents contamination by microorganisms
What does the growth medium contain?
Nutrients and growth hormones
What are the advantages of growing plants by tissue culture?
Fast and simple process
Requires little space
Enables the growth of many plant clones with same desirable characteristics
Useful in the preservation of endangered plant species
What are the disadvantages of growing plants by tissue culture?
Reduction in the gene pool
Plant clones often have a low survival rate
Could unknowingly increase the presence of harmful recessive alleles
Why is animal tissue culturing useful?
Useful in the preparation of tissue samples for medical research
Enables the investigation of how different factions may affect a specific animal tissue, without harming the animal itself
Why is animal tissue culturing useful?
Useful in the preparation of tissue samples of medical research
Enables the investigation of how different factors may affect a specific animal tissue, without harming the animal itself.
Describe how animal tissue cultures are prepared
What is genetic engineering
The modification of the genome of an organism by the insertion of a desired gene from another organism.
Describe the process of genetic engineering
DNA is cut at specific base sequences by restriction enzymes to create sticky ends
Vector DNA cut using the same restriction enzymes to create complementary sticky ends
Ligase enzymes join the sticky ends of the DNA and vector DNA forming recombinant DNA
Recombinant DNA mixed with and “taken up’ by target cells
Describe the benefits of genetic engineering
Describe the risks of genetic engineering
