B13 Evolution and Classification Flashcards
What are the 2 types of variation?
Genetic and environmental variation
Which of the following is not a form of environmental variation?: Yellow leaves, suntan, blue eyes
Blue eyes
What does a mutation produce?
A genetic variant
How can mutations lead to variation?
The gene becomes altered, so will code for a different amino acid, potentially leading to changes in the protein that it codes for, leading to phenotype changes.
Why do most mutations not change an organism’s phenotype?
Most mutations have little to no impact on the protein being coded for.
Summarise the theory of evolution by natural selection:
- Populations of a species show phenotypic variation due to genetic variants
- Some mutations give rise to characteristics that facilitate better survival
- The organisms with the variant are more likely to survive and reproduce
- Reproduction rate is higher among those with the desirable characteristics, and they become more prevalent in the population; the species evolves
When does speciation occur?
When the characteristics of a group of organisms diverge so greatly from the initial population that they can’t interbreed
List 3 ways in which a species could go extinct:
- A new predator wipes them out
- A disease wipes them out
- A catastrophic event occurs
List 2 reasons why Darwin’s theory wasn’t fully accepted initially:
- Contradicted religious attitudes- removed need for a ‘Creator’
- No explanation for why characteristics arose
Summarise Lamarck’s theory of evolution:
Changes in characteristics that an organism acquires over the course of its life are passed onto the offspring.
e.g. A rabbit’s legs may grow longer from running from predators, and the rabbit would pass that onto its offspring
Describe the basic process of selective breeding (4 steps):
- Select organisms with desired characteristics
- Breed them with one another
- Breed the best of the offspring
- Continue the process to increase the prevalence of the characteristic
What may dogs be selectively bred for?
A gentle temperament
List 2 disadvantages of selective breeding:
- Reduces variety- lowers species’ ability to adapt to changes
- Increased risk of autosomal recessive disorders
In genetic engineering, how is a desired gene isolated from an organism’s genome?
It is cut out with an enzyme.
Where is the gene inserted after isolation in genetic engineering?
Into a vector, like a virus or bacterial plasmid, which is then introduced to the target organism
Name one application of genetic engineering:
Used in insulin production for the treatment of type 1 diabetes- insulin genes are inserted into bacteria
List 2 advantages of genetic engineering in crop production:
- Increased yield
- Crops can be engineered to contain essential nutrients
List 2 disadvantages of GM crops:
- Long-term health effects are not known
- Affects number of wild flowers + insect population reducing farmland biodiversity
Describe the process of tissue culture:
Plant cells are placed into a hormone-containing growth medium and form new, clone plants.
Describe how animals can be cloned using embryo transplantation:
- Sperm cells are taken and used to artificially fertilise an egg cell
- The developing embryo splits before cells become specialised
- Embryo clones are implanted into animals and produce genetically identical offspring
Describe the process of adult cell cloning:
The nucleus is taken from an unfertilised egg cell and replaced with that of an adult body cell. The egg cell is then stimulated using an electric shock so that it divides.
List 2 benefits of cloning
- Can be used to preserve endangered species
- Produces many ‘ideal’ characteristics
List 2 disadvantages of cloning:
- Reduced gene pool
- Potential health issues
List 3 ways in which fossils form:
- Mineral replacement as remains decay
- Casts/impressions
- Preservation
Why is peat so effective at fossil preservation?
The conditions are too acidic for the microbes that mediate decay.
Why is there a lack of evidence on how life began on earth?
- It is believed that early organisms were soft-bodied (don’t fossilize)
- Primordial fossils may have been destroyed by tectonic activity
What is a species?
Group of organisms that can mate and produce fertile offspring
What is speciation?
The development of a new species
List 2 steps leading to speciation:
- Isolation
- Natural selection
Why can antibiotic resistance increase so quickly?
Bacteria reproduce rapidly, passing on the resistance gene to their offspring.
List 3 ways of preventing the spread of antibiotic resistance:
- Reducing population usage of antibiotics
- Finishing full course of antibiotics
- Reducing use in agriculture
Define mutation
A random change in an organism’s DNA
Define selective breeding
Breeding organisms within a certain gene pool to increase the prevalence of ideal characteristics
