Natural Selection And Genetic Modification Flashcards
Why did people start thinking humans were animals?
Carl Linnaeus published his system of classification and suggested that humans were related to monkeys
What was Carl Linnaeus’ system of classification?
Binomial system
What is evolution?
A gradual change in the characteristics of a species over time
Why do fossils not show smooth changes over time?
Some have not been discovered
Features of the Ardipithecus ramidus (Ardi)
- 1.2m tall
- legs shoe it may have been able to walk upright
- long arms & long big toe that would have allowed it to climb trees
Features of the Australopithecus afaerensis (Lucy)
- 1.07m tall
- could probably walk upright
- toe bones arranged in same way as modern humans but they were more curved
Features of homo habilis
- short
- long arms
- walked upright
Features of homo erectus
- tall (1.79m)
- strongly built
What is the earliest scientists can see human-like animals using stone tools?
3.3 million years ago
How do scientists know how old the tool is?
They can work out the ages of the layers of rock and assume the tool is the same age as that layer of rock
What would the oldest stone tools be used for?
Simple, but would have helped with skinning an animal or cutting up meat
Who came up with evolution?
Charles Darwin and Alfred Russel Wallace
What is genetic variation?
The characteristics of individuals vary (due to differences in genes)
What is environmental change?
Conditions change in an area change
What is natural selection?
By chance, the variations of some individuals make them better at coping with the change than others, and more likely to survive
What is inheritance?
The survivors breed and pass on their variations to their offspring. So the next generation contains more individuals with the ‘better adapted variations’
What are the stages of evolution?
- genetic variation
- environmental change
- natural selection
- inheritance
- evolution
What is a pentadactal limb?
A limb that has 5 digits (fingers and thumbs)
Give examples of some animals that have the pentadactal limb
- human
- bat
- chicken
- turtle
- dolphin
What do the pentadactal limb similarities suggest?
Evolution from a common ancestor
What are the 5 kingdoms?
- animals
- plants
- fungi
- protists
- prokaryotes
What are the 3 domains?
- archaea
- bacteria
- eukarya
What are the main characteristics of animals?
- multicellular (with cells arranged as tissues and organs)
- no cell walls
- cells have nuclei
What are the main characteristics of plants?
- multicellular (with cells arranged as tissues and organs)
- chloroplasts
- cells have nuclei
- cellulose cell walls
What are the main characteristics of fungi?
- multicellular (apart from yeast)
- live on or on the dead matter they feed off
- cells have nuclei
- cells walls contain chitin (not cellulose)
What are features of protists?
- mostly unicellular
- cells have nuclei
- some have cell walls (made of different substances not chitin)
Features of prokaryotes
- unicellular
- cells do not have nuclei
- flexible cell walls
What are the features of archea?
- cells with no nucleus
- genes contain unused sections of DNA
What are the features of bacteria?
- cells with no nucleus
- no unused sections in genes
Features of eukarya
- cells with a nucleus
- unused sections in genes
What is artificial selection?
When humans choose certain organisms because they have useful characteristics, such as sheep with thick wool
What is selective breeding?
When humans choose an organism that has a certain characteristic and breed to have more of these organisms, making that chosen characteristic more and more obvious
What are plants and animals often selectively bred for?
- disease resistance
- yield (how much useful product they make)
- coping with certain environmental conditions
- fast growth
- flavour
What is genetic engineering?
Altering the genome of an organism, usually by adding genes from another species (also known as genetic modification)
What is tissue culture?
The growing of cells or tissues in a liquid containing nutrients or on a solid medium
What is a callus?
A clump of undifferentiated cells
What is tissue culture used for?
- To produce new plants if very rare species which are at a risk of extinction
- to produce more individuals of plant species that may be difficult to grow from seed
- produce clones of GM plants
What are uses of tissue cultures in medicine?
- to study viruses
- to study how cells communicate with each other
- cultures of cancers used to study cancer
What are the risks of selective breeding?
- only certain alleles are selected, others become rare or disappear
- all organisms are very similar so if there is a change in conditions (e.g a new disease)affects one organism all the others are affected
What are the issues with genetic engineering?
- seeds are expensive
- there’s genes may have unknown consequences in wild plants
- not all people can use the insulin from GM bacteria
What are insecticides?
A substance used to kill pests
What is an advantage of GM bt toxin?
- It only affects insects that chew the plants tissues
- insect predators unharmed
Problems with crop plants that make their own insecticide?
-insects can develop resistance to toxin
What is a biological control?
Using organisms to control pests
