Topic 4: Natural Selection And Gene Modification Flashcards
What is the binomial system for naming animals.
It uses two Latin words for naming species and is still used today.
What did James Burnett propose about humans and how did they react?
During the 18 century he proposed that humans had evolved from apes or monkeys. However most people thought he was mad as they believe strongly in Christianity. Fossils found today though show he was on the right track.
What is evolution?
A gradual change in characteristics of a species over time.
How have scientists discovered human evolution?
Scientists use fossils to find out about human evolution. They work out how old the fossil is and put them in age order. The fossils though do not show a smooth change over time because some have not been discovered.
What is Ardi?
In 1992 scientists discovered some 4.4 million year old fossils form a female of an extinct species. More fossils of this species were found and named Ardipithecus ramidus. The most complete set of these fossils is called Ardi.
What was Ardi like and what features of her body were adapted?
Ardi was about 1.2 tall and 50 kg. Her leg bones show she may have been able to walk upright. She had very long arms and very long big toe bones that stuck out at the sides of her feet that would have allowed her to climb trees easily.
When was the Australopithecus afarensis discovered and what was her nickname?
It nickname was Lucy and it was discovered in 1947. She lived 3.2 million years ago and was about 1.07m tall. She could probably walk upright, but although her toe bones were arranged in the same way as those of modern humans they were much more curved.
What spicers was found in the 1960s and how closely related to humans are they?
A more human like species was found. They decided it was closely linked to modern humans(homo sapiens) and so have it the name homo habilis which translates to handy man.
Their fossils are 2.4-1.4 million years old. The animals were quite short with long arms but walked upright.
What is the Homo erect is and when and where was it discovered?
It was discovered in Asia in the late 19th century and so several scientists thought that modern humans involved in Asia. However an almost complete 1.6 million year old human skeleton was found in 1964 in Kenya providing evidence humans evolved in Africa. The species was strongly build and 1.79m tall.
When was the earliest stone tools discovered?
The earliest evidence of human like animals using stone tools dates back to about 3.3 million years ago.
How do scientists know what stone tools came from what era?
Scientist can work out the ages of different layers of rock. They then assume that a stone tool is about the same age of a layer of rock.
How have stone tools developed and what are some of their purposes?
The oldest stone tools are very simple but would have helped with:
- skinning animals
- cutting up meat
- using it as some sort of weapon
Tools found in more recent rocks are more sophisticated.
What did Charles Darwin and Alfred Russel Wallace publish during the 18 century?
During the 18th century people started to accept that organisms slowly evolved into others. The two scientists came up with the same idea about how this happened. The first book about this was published by Darwin and published in 1859.
What were the series of stages involved in Darwin’s theory of evolution?
Genetic variation: the characteristics of an individual vary (due to differences in genes)
Environmental change: conditions in an area change. For example the lack of a resource such as food causes more competition between organisms.
Natural selection: by chance the variations of some individuals make them better at copying with the change than others and are more likely to survive. (‘Survival of the fittest’)
Inheritance: the survivors breed and pass of their variations to their offspring. So the next generation contains more individuals with ‘better-adapted variations.’
Evolution: if the environment conditions remained changed natural selection occurs over and over again and a new species evolves with all the individuals having ‘better-adapted variations’
What is natural selection?
Part of Darwin’s theory of evolution. By chance some individuals inherit characteristics that allow them to survive better than others in a certain area.
How are elephants and mammoths linked and how did they evolve?
Woodly mammoths evolved from the same animals; THEY SHARE A COMMON ANCESTOR. Scientists think that the area in which this ancestor lived started to get colder. Due to genetic variation one animals by chance had harrier skin. They were more likely to therefore survive the cold than less hairy animals, especially when food was scarce. More of these individuals survived and bred. Over time the animals became hairier and hairier until they formed a new species.
Why and rats become immune to warfarin and how was this evolution?
In the 1940s and 1950s a substance called warfarin was used to poison rats. When is was first used most rats does but within 10 years most rats were resistant to it. Due to genetic variation some rats had always been resistant. As the poison killed the non-resistant rats, the only ones left to breed were resistant.
How have antibiotic adapted to become resistant to bacteria?
In a population of bacteria some bacteria are more resistant than others and take longer to be killed. People who take an antibiotic to cure an infection often stop taking it too early, because they feel better. This leaves resistant bacteria still alive. They reproduce and spread, causing infection that cannot be treated with the antibiotic because now all the bacteria are resistant. The problem of resistant bacteria was not present when they were first used.
What do Darwin notice when he visited Galápagos Islands in 1835?
He noticed differences between mockingbirds on different islands. He wondered weather a species could change form if it moved into a different area. He collected birds from different islands to study them.
When Darwin read Thomas Malthus’ essay what did it state and what ideas did Darwin start to form?
It argues of people had too many children, there would not be enough food. In the resulting struggle for survival some children would die. This gave Darwin the idea that organisms normally produced more offspring than could survive. Only those individuals best suited to the surroundings would survive and reproduce to pass on their characteristics.
What did Alfred Wallace write about to Darwin and what observations had he made?
In 1858 Darwin received a letter from Wallace, who was studying organisms in Indonesia. Wallace had already read Malthus’ essay and had come to the same conclusion Darwin had.
Why did some people have trouble coming to terms with Darwin’s theory of evolution and why was there a lack of evidence.
Christians believed God had created the world so this went against their believes and caused controversy but the idea was slowly excepted. However Darwin couldn’t explain how variation occurred and the evolution of characteristics in fossils were not gradual (jumped back and forth due to lack of fossils being discovered)
What is the pentadactyl limb?
The fact that vertebrates have limbs with 5 fingers. Initially this idea was published in Darwin’s book on the ‘origin of species’.
What did Darwin suggest about the pentadactyl limb?
He made the point that a human would design structures differently for flying swimming and walking. The limb bone similarities suggest evolution from a common ancestor and not that the bones are designed for a specific purpose independently of one another.
Examples of animals with the pentadactyl limb?
Turtle Human Dolphin Bat Chicken
What was the classification system?
It divided organisms in to groups based on what they looked liked. The largest Kingdoms were plants and animals, which were divided into even smaller groups.
What do organisms of a kingdom/groups all have in common?
The characteristics of an organism in a group got more and more similar as the groups got smaller and smaller. The last groups contained one type of organism.
What problems did classification cause?
It caused problem for organisms that have evolved similar characteristics but are not closely related.
Once scientists accepted the idea of evolution, they started to work out how different organisms had evolved and to alter the classification system so that smaller groups contained organisms that had all eveolved form event common ancestors.
What were the five kingdoms?
Animals Plants Fungi Protists Prokaryotes
What are the moan characteristics of an animal?
Multicellular(with cells arranged as tissues and organs)cells have a nuclei but no cell wall.
What are the main characteristic of a plant?
Multicellular (with cells arranged as tissues and organs) have chloroplasts for photosynthesis, cells have a nuclei and cellulose cell walls.
What are the main characteristics of a fungi?
Multicellular (apart from yeast) live in or on dead matter in which they feed. Cells have a nuclei, cell walls contain chitin (not cellulose)
