topic 4 - evolution

what animal species are humans most closely related to

chimpanzees

evidence for human evolution: Ardi (4.4 MYA ago)

• skull volume = 350cm³

• pelvis and slightly in-turned femurs show that Ardi was bi-pedal

• long and curved big toe

evidence for human evolution: Lucy (3.2 MYA ago)

• skull volume = 400cm³

• femurs point in to support centre of mass when walking on two feet (Lucy was fully bi-pedal)

• big toe is no longer pointed out

evidence for human evolution: homo erectus (1.6 MYA ago)

• skull volume = 850cm³

• first species to leave Africa (all fossils originated from Africa)

evidence for human evolution: development of stone tools over time

As skull volume increases over time, the sophistication of stone tools (created by the homo habilis) increases, therefore meaning the sophistication of stone tools is directly proportional with skull volume

natural selection definition

• variations that make some individuals of a species

• better at coping with environmental change than others

• which makes them more likely to survive to reproduce

• and pass the desirable genes to their offspring

when does evolution occur

• after many generation of natural selection

• can cause a new species to evolve

• which contains the better-adapted genes

requirements for natural selection to occur

1. genetic variation within a population leading to varying characteristics

2. environmental change that leads to differences in reproductive success

3. inheritance causing offspring to inherit same alleles that allowed their parents to reproduce

Darwin’s theory of evolution through natural selection

1. individual organisms within a particular species show a wide variety of characteristics

2. individuals with characteristics most suited to the environment are more likely to survive to reproduce

3. the ‘superior’ genes are passed down to offspring through inheritance

4. occurs through multiple generations

how has the emergence of resistant organisms supported Darwin’s theory (bacteria)

• organisms such as bacteria have shown genetic variation throughout their population

• some of the population would have contained a gene that is resistant to antibiotics

• as antibiotics became more commonly used, bacteria that was not resistant antibiotics died out

• causing the population that was left to only contain the gene that coded for resistance to antibiotics

• demonstrating that the bacteria that contained the gene for antibiotic resistance

• were more likely to survive than those without

• and therefore more likely to reproduce

describe the work of Darwin and Wallace in the theory of evolution by natural selection

• both Darwin and Wallace noticed a difference in the characteristics of the same species when travelling.

• through this discovery, they worked out that the same species have differing characteristics in different places as these differing characteristics allow them to survive to reproduce better in their own environment.

explain the impact of the theory of evolution by natural selection on modern biology

led to the realisation that conserving the genetic diversity of a species is important as it helps species to adapt to changing environments.

how has the pentadactyl limb provided scientists with evidence for evolution

the pentadactyl limb is found in many species, such as horses, humans and whales. this means that all these species and more must have a common ancestor as they are not the same species but all contain a pentadactyl limb.

describe how genetic analysis has led to the suggestion of three domains instead of five kingdoms classification method

• three domains = archaea, bacteria, eukaryotes

• five kingdoms = animals, plant, prokaryote, protist, fungi

  many species that were classified together in the five kingdoms weren’t similar on a genetic level, leading to the creation of the three domains

explain selective breeding

• when humans actively choose which parents of the species can reproduce together

• to create an offspring with the desired characteristic/s

explain the impact of selective breeding on food plants

• can increase the yield

• can make the entire species more prone being destroyed by environmental change

explain the impact of selective breeding on domesticated animals

• can improve the aesthetic value of a species

• can create problems the specie didn’t struggle with previously (e.g pugs squished faces that were selectively bred causing breathing problems)

describe genetic engineering

• process which involves

• modifying the genome of an organism

• to introduce desirable characteristics

describe the process of tissue culture

• method of biological research

• in which fragments of tissue from an animal or plant

• are transferred to an artificial environment

• in which they can continue to grow and function

describe the advantages of tissue culture in medical research

• can test medicine and drugs in a more ethical way on the cultured tissue

• can grow new organs which limits the threat to the donor and of the patient’s body rejecting the organ

describe the advantages of tissue culture in plant breeding

• rare species on the verge of extinction can have a better chance at surviving

• species that are hard to reproduce can reproduce easier in the controlled environment

evaluate the benefits of genetic modification in agriculture and medicine

• Improve crop yields or crop quality, which is important in developing countries. This may help reduce hunger around the world.

• Insect and pest resistance can be developed and inserted into the plants. The plant produces toxins, which would discourage insects from eating the crop.