Edexcel Biology Gcse - Evolution Part 2
Penicillin, the first mass-produced antibiotic in the 1940s, revolutionized medicine by treating bacterial infections. However, overuse has led to antibiotic-resistant bacteria, making infections harder to treat. The slow development of new antibiotics has raised concerns about a future where even simple infections could become deadly.
Antibiotic resistant bacteria
overview
Penicillin was the first antibiotic to be produced on a mass scale in the 1940s. It is derived from the Penicillium fungus, shown here growing on an agar plate.
Many new types of antibiotics were discovered during the 1950s and 1960s, but more recently, this has slowed greatly.
Recent concerns of increasing resistance have created the need for new antibiotics, but they are costly and very slow to develop. Some scientists fear that we are fighting a losing battle against resistant bacteria, which may ultimately lead to people dying from simple infections, for example following operations.
Key Terms
Antibiotic resistant bacteria
overview
Penicillin was the first antibiotic to be produced on a mass scale in the 1940s. It is derived from the Penicillium fungus, shown here growing on a...
Evidence of evolution - Rock fossils
A fossil is the preserved remains of a dead organism from millions of years ago. Fossils are found in rocks and can be formed from:
hard body parts, such as bones and shells, which do not decay easily or are replaced by minerals as they decay
parts of organisms that have n...
Evidence of evolution - Rock fossils
The fossil record
Fossil remains have been found in rocks of all ages. Fossils of the simplest organisms are found in the oldest rocks, and fossils of more complex o...
Tools as evidence for human evolution
Tools also provide evidence for human evolution. Primitive tools (flint hand axes) have been found in remains from the Palaeolithic Age (10,000 to ...
The pentadactyl limb
Many vertebrates have a very similar bone structure despite their limbs looking very different on the outside. This structure is known as the penta...
The pentadactyl limb
| horses
The pentadactyl limb seen in the horse provides an excellent example of how evolution has happened. As the marshy ground became drier, horses with ...
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| Term | Definition |
|---|---|
Antibiotic resistant bacteria overview | Penicillin was the first antibiotic to be produced on a mass scale in the 1940s. It is derived from the Penicillium fungus, shown here growing on an agar plate. Many new types of antibiotics were discovered during the 1950s and 1960s, but more recently, this has slowed greatly. Recent concerns of increasing resistance have created the need for new antibiotics, but they are costly and very slow to develop. Some scientists fear that we are fighting a losing battle against resistant bacteria, which may ultimately lead to people dying from simple infections, for example following operations. |
Evidence of evolution - Rock fossils A fossil is the preserved remains of a dead organism from millions of years ago. Fossils are found in rocks and can be formed from: | hard body parts, such as bones and shells, which do not decay easily or are replaced by minerals as they decay parts of organisms that have not decayed because one or more of the conditions needed for decay are absent for example, dead animals and plants can be preserved in amber, peat bogs, tar pits or in ice preserved traces of organisms, such as footprints, burrows and rootlet traces - these become covered by layers of sediment, which eventually become rock |
Evidence of evolution - Rock fossils The fossil record | Fossil remains have been found in rocks of all ages. Fossils of the simplest organisms are found in the oldest rocks, and fossils of more complex organisms in the newest rocks. This supports Darwin’s theory of evolution, which states that simple life forms gradually evolved into more complex ones. Evidence for early forms of life comes from fossils. By studying fossils, scientists can learn how much (or how little) organisms have changed as life developed on Earth. There are gaps in the fossil record because many early forms of life were soft-bodied, which means that they have left few traces behind. What traces there were may have been destroyed by geological activity. This is why scientists cannot be certain about how life began. |
Tools as evidence for human evolution | Tools also provide evidence for human evolution. Primitive tools (flint hand axes) have been found in remains from the Palaeolithic Age (10,000 to 2.5 million years ago). More advanced tools (arrowheads) have been found from the Mesolithic Age (6,000 to 10,000 years ago), and even more advanced tools have been found from the Neolithic Age (4,000 to 6,000 years ago). These dates are only approximate, as the tools have been dated from the environments they were found in. This is often the layers of sediment surround the tool. Dating can be done by radiocarbon dating or other techniques which look at the amounts of elements like iron or potassium. It is the assumed that the tool is approximately as old as the rock which surrounds it. |
The pentadactyl limb | Many vertebrates have a very similar bone structure despite their limbs looking very different on the outside. This structure is known as the pentadactyl (five fingered) limb. This suggests that many vertebrates descended from the same common ancestor. Although the limbs of crocodiles, birds, whales, horses, bats and humans all look very different they share the same five fingered bone structure. This provides evidence for the theory of evolution. |
The pentadactyl limb | horses | The pentadactyl limb seen in the horse provides an excellent example of how evolution has happened. As the marshy ground became drier, horses with smaller feet were generally faster. They had an evolutionary advantage because they were able to avoid predators. Over many, many generations horse's feet have evolved to be smaller and the horses themselves taller and stronger. |
Linnaean system of classification | overview | Living organisms are classified into groups depending on their structure and characteristics. This system was developed in the eighteenth century by Carl Linnaeus. The classification of species allows the subdivision of living organisms into smaller and more specialised groups. |
Kingdoms | Linnaean system of classification | The first division of living things in the classification system is to put them into one of five kingdoms. The five kingdoms are: animals (all multicellular animals) plants (all green plants) fungi (moulds, mushrooms, yeast) protists (amoeba, chlorella and plasmodium) prokaryotes (bacteria, blue-green algae) |
Linnaean system of classification Living things can then be ranked according to: (least to most specific) | Kingdom phylum class order family genus species |
(Linnaean system of classification) | Phylum follows Kingdom and has many different organisms, including three examples from the Animal Kingdom: | chordata, which have backbones arthropod, which have jointed legs and an exoskeleton annelids, which are segmented worms |
(Linnaean system of classification) | Class is an additional sub-division, which for example, results in the Chordata phylum being divided into: | mammals birds amphibians fish reptiles |
(Linnaean system of classification) Order follows class and as an example, mammals can be further sub-divided into a variety of different groups such as: | carnivores | - primates |
(Linnaean system of classification) | Orders are broken down into families. Here are a few examples of which carnivores can be divided into: | canidae - dogs | - felidae - cats |
(Linnaean system of classification) | Genus, the Felidae family can be further sub-divided into four genus examples: | acinonyx - cheetah panthera - lion and tiger neofelis - clouded leopard felis - domestic cats |
(Linnaean system of classification) | Species is the final classification stage, and the genus panthera can be divided into: | panthera leo (lion) | - panthera tigris (tiger) |
(Linnaean system of classification) | As an example, the complete breakdown of the classification of lions: | kingdom - animal phylum - vertebrate class - mammal order - carnivorous family - felidae genus - panthera species - panthera leo |
Mnemonic to remember order of classification of living organisms. | Kids prefer candy over fresh green salad |
Impact of modern developments of classifying systems | Technology associated with biology has advanced throughout the years, which has allowed the current classification system to be enhanced by using genetic analysis of DNA sequences. Originally Linnaeus' system relied purely on human judgement in order to compare the characteristics of various organisms. Now the comparisons of DNA sequences have allowed the relationship of organisms to be explored further. In some cases, species that are more closely related may have fewer differences contained within the DNA sequences. DNA sequences are shown as the order of DNA bases, abbreviated as A, C, G and T. There has been debate in history over the classification of the red panda and the giant panda. Some argued that they should belong to the bear family and others argued that they are more like racoons. Following the development of DNA sequencing technology, it has been shown that the red panda and ginat panda are not very closley related genetically. DNA analysis showed the giant panda to be a bear, and the red panda to be more closely related to a racoon. |
Impact of modern developments of classifying systems | Three-domain system | Classification systems have continued to be developed by other scientists, such as Carl Woese who developed the three-domain system. This is based on evidence genetic analysis. Genes of an organism code for proteins. It has been demonstrated that some organisms have parts of their genes that are not used in making proteins and other organisms that use entire genes to code for proteins, with no unused portions. This information has informed the three-domain system. |
Impact of modern developments of classifying systems Three-domain system The system divides organisms into: | Archaea (primitive bacteria): These cells usually live in extreme environments. They have no nucleus and have unused sections of genes. Bacteria (true bacteria): Bacteria cells have no nucleus and no unused sections of genes. Eukaryota (including protists, fungi, plants and animals): These have a nucleus and have unused sections of genes. |
What is Archaea? | Archaea (primitive bacteria): | These cells usually live in extreme environments. They have no nucleus and have unused sections of genes. |
What is Bacteria? | Bacteria (true bacteria): | Bacteria cells have no nucleus and no unused sections of genes. |
What is Eukaryrota? | Eukaryota (including protists, fungi, plants and animals): | These have a nucleus and have unused sections of genes. |
Examples of bacteria. | Cyanobacteria | - Heterotrophic bacteria |
Examples of archaea. | Halophiles | - Thermophiles |
Examples of eukaryota. | Animals Fungi Plants Chromists Alveolates Rhodophytes Flagellates Basal protists |
Why can bacteria evolve more quickly than other species? | Bacteria can evolve more quickly because they reproduce quickly. |