B4 Natural Selection and Genetic Modification Flashcards
Define
evolution.
the gradual change in the characteristics of a species over time
What is a
cladogram?
a tree diagram showing the evolutionary relationships and common ancestors
What are
nodes?
(on cladograms)
branching points which indicate a speciation event when a common ancestor splits into two or more species
When was ‘Lucy’ alive?
3.2 million years ago
When was ‘Ardi’ alive?
4.4 million years ago
What is the genus and species of
‘Lucy’?
Australopithecus afarensis
What is the genus and species of
‘Ardi’?
Ardipithecus ramidus
What can fossil skulls tell us about a species?
- diet
- age
- brainsize
What are the six categories of fossil types?
- trace
- mould and cast
- replacement
- petrified or permineralized
- amber
- original material
What is a
trace fossil?
and what are some examples?
any indirect evidence left by an organism
some examples are footprints, burrow and fossilized feces
What are
mould and cast fossils?
a mould is an impression of an organism
a cast is a mould filled with sediment
What are
replacement fossils?
fossils where the original material of an organism is replaced with mineral crystals that can leave detailed replicas of hard or soft parts
What are
petrified or permineralized fossils?
empty pore spaces that are filled in by minerals
What are
amber fossils?
Preserved tree sap that traps an entire organism. The sap hardens into amber and preserves the trapped organism.
What are
original material fossils?
original organisms that have been preserved by mummification or freezing
What are some of the problems that exist with using fossils solely as evidence for human evolution?
- fossils are very rare
- skeletons are often incomplete
- the specimen might be an anomolous case
What are the 4 stages of classic fossilisation of a dinosaur?
- Dinosaur dies
- All soft tissues decay
- Earth is layered on top
- The bones become mineralised
Define
genetic variation.
Individuals in a population vary in their characteristics as a result of differences in their genes.
Explain
Darwin’s theory of evolution.
-
GENETIC VARIATION
Individuals in a population vary in their characteristics as a result of differences in their genes. -
COMPETITION
Individuals compete for resources. Some variations are better adapted to getting recources than others. -
NATURAL SELECTION
Individuals with better-adapted variations are more likely to survive and reproduce. -
INHERITANCE
The next generation will contain more individuals with the ‘better adapted variations’. -
EVOLUTION
If the environment changes, natural selection will favour different variations. Over many generations, most of the individuals in the population will have the different ‘better adapted variations’. This may result in a new species.
What are the 5 kingdoms in the
5 kingdom classification?
- plants
- animals
- fungi
- protists
- monerans
Why has genetic analysis shown that some relationships in the 5 kingdom system were incorrectly identified?
Because the characteristics were similar due to adaptation to the same environment rather than inheritance.
Why is
genetic evidence better than evidence from observable characteristics for classification?
DNA isn’t changed by the environment.
What are the three domains of the three domain system?
- bacteria
- archaea
- eukaryota
What is the kingdom in the bacteria domain?
enbacteria
What is the kingdom in the archaea domain?
archaebacteria
What are the kingdoms in the eukaryota domain?
- protista
- fungi
- plants
- animals
Define
selective breeding.
A technique where humans control which organisms breed together to enhance their natural characteristics for human use.
Define
genetic engineering.
A process which involves changing the DNA of one organism by inserting genes from another organism. This creates genetically modified organisms and is another way to introduce desirable characteristics to organisms.
Define
aseptic technique.
the process of keeping things sterile
What is
tissue culture?
The growing of cells or tissues in a liquid containing nutrients or on a solid medium (such as nutrient agar). The genetically identical cells form a clump called a callus. These cells may be treated to differentiate.
Define
callus.
a clump of undifferentiated cells
Define
differentiate.
become specialised
Describe the stages of
micropropagation.
- A piece of plant is placed in bleach solution to sterilise it.
- A small piece of plant is cut off and placed on sterile nutrient medium to grow.
- The piece of plant is treated with hormones so that it grows roots and shoots.
- When the plants are large enough, they are planted into soil or compost.
What are the positives of
micropropagation?
- a large number of plants can be grown in a short period of time
- healthy plants can be grown from diseased plants
- plants without seeds can be multiplied
- it is useful where sexual reproduction is not possible
What are the negatives of
micropropagation?
there is no variation - a disease could wipe out the entire batch
Why are bacteria very useful for genetic engineering?
- they have plasmids
- they reproduce asexually
Define
vector.
A vehicle for carrying foreign DNA into a cell. It is used to transfer donor genes into recipient cells.
What is the most commonly used vector in genetic engineering?
a plasmid
and additional genes are added to it
What is
recombinant DNA?
a plasmid which has had genes from another organism inserted into it
What are the different steps of
humans insulin production?
- There is a human pancreas cell containing DNA and a bacterium containing bacterial DNA and plasmid DNA.
- The human insulin producing gene is cut out of the human pancreas cell using restriction enzymes to create sticky ends.
- The plasmid DNA is cut out by the same technique to create complementary sticky ends.
- The two types of DNAs are combined to form recombinant DNA. Ligase enzyme is used to seal the ends.
- This recombinant DNA is introduced into a bacterial cell.
- These bacterial cells are put into a fermentation tank so that they can multiply rapidly.
- These recombinant bacteria produce human insulin.
- The insulin is extracted and purified.
What are the benefits of
genetic engineering in crops?
- the nutritional value of foods could be improved
- crops can be produced that lack known allergens
- crops can grow in arid conditions for better yield
- genetically modified crops can produce herbicides to kill pests
- food supply/agriculture can be improved in poor countries
- genetically modified crops may have longer shelf lives
- gowing insect resistant genetically modified crops reduces the amount of chemical used on crops to kill insects
- growing herbicide resistant genetically modified crops makes it easier to kill weed but not crops
- there is no evidence of harm to health from genetically modified crops so far
- genes and proteins are broken down in the digestive system regardless of whether the food is genetically modified or not
- less spraying is needed for genetically modified crops than for non-genetically modified varieties
- economic costs and carbon footprint can be reduced because there is less need for land clearing and pesticide usage
What are the risks of
genetic engineering in crops?
- new traits could cause adverse health reactions
- removals of traits coud have unkown effects
- crops may limit biodiversity of local environment
- cross pollination could lead to ‘super weeds’
- foods with genetically modified components may not be labeled
- different governments may have conflicting regulatory standards concerning safe usage
- growing herbicide resistant genetically modified crops means that farmers can only use the herbicide that the crop is resistant to
- if the insect resistance gene was transferred to weed plants, insects would be killed eating wild plants as well as crops
- insects could evolve to stop being affected by a particular herbicide
- genetically modified seed is usually more expensive than non-genetically modified seed
- new genetically modified seed must be bought each year
What is
Bt Maize?
A genetically modified Maize crop that has a bacterial gene known as Bt (derived from the soild bacterium Bacillus thuringiensis) inserted into its genome. This gene produces a protein that is toxic to insect pests.
Define
yield.
the amount of food we get from a crop
