1
Q
What is classification?
A
The process by which living organisms are sorted into groups. The organisms within each group share similar features.
2
Q
What is the classification system?
A
Until recently, most widely used system had 7 taxonomic groups ordered in hierarchy. Taxonomic hierarchy: 1. Kingdoms. (Most broad) 2. Phylum. 3. Class. 4. Order. 5. Family. 6. Genus. 7. Species. (Most specific) Now scientists add another level at the top called ‘domain’.
3
Q
Why do scientists classify organisms?
A
- To identify species - easily identified through the clearly defined system.
- To predict characteristics- if several members in a group have a specific characteristic. It is likely that another species in the group will also have it.
- To find evolutionary links- species in the same group probably share a characteristic because they have evolved from a common ancestor.
- By using a single classification system, scientists worldwide can share research.
4
Q
How are organisms classified?
A
- Organisms are separated into the 3 domains: Archaea, bacteria, eukarya. These are the broadest groups.
- As you move down, there are more groups at each level but fewer organisms in each.
- System ends with organisms being classified as individual species = smallest unit of classification.
5
Q
What is meant by species?
A
A group of organisms that are able to produce fertile offspring.
6
Q
What are homo sapiens?
A
The scientific name for the human species.
7
Q
How were organisms named in the past + disadvantages?
A
According to physical characteristics:
- organisms may have more than one common name.
- different names in different languages.
- doesn’t provide info about the relationships between organisms.
8
Q
Explain binomial nomenclature.
A
Carl Linnaeus developed this system in 18th century to ensure all scientists around the world are discussing the same organism. It is a method of naming.
All species are given a scientific name consisting of two parts:
- first word= indicates organisms genus. Is the generic name.
- second word= indicates organisms species. Is the specific name.
No two species have the same generic and specific name
Scientific name is written in italics or underline. Only first letter of genus is capital.
9
Q
What are the 5 kingdoms?
A
- prokaryotae. (Smallest)
- protoctista.
- fungi.
- plantae .
- animalia. (Largest)
Organisms were originally classified into these based on similarities in observable features.
10
Q
Features of prokaryotae?
A
- bacteria.
- unicellular.
- no nucleus/membrane bound organelles.
- small ribosomes. Ring of naked dna.
- no visible feeding mechanism: nutrients absorbed through cell wall or produced internally by photosynthesis.
11
Q
Features of protoctista?
A
- mainly unicellular.
- have nucleus and other membrane bound organelles.
- some have chloroplasts.
- some are sessile. Others move by cilia/flagella/amoeboid mechanisms.
- nutrients acquired by: photosynthesis (autotrophic feeders), indigestion of other organisms (heterotrophic feeders) or both- some are parasitic.
12
Q
Features of fungi ?
A
- unicellular or multicellular.
- nucleus and membrane bound organelles. Cell wall composed mainly of chitin.
- no chloroplasts/chlorophyll.
- no locomotion mechanisms.
- body/mycelium made of threads or hyphae.
- nutrients acquired by absorption- mainly from decaying material. Are saprophytic feeders. Some are parasitic.
- most store food as glycogen.
13
Q
Features ofplantae?
A
Over 250000 species.
- multicellular.
- nucleus, other membrane bound organelles, chloroplasts, cellulose cell wall.
- all contain chlorophyll.
- most don’t move. (gametes of some move using cilia/flagella)
- autotrophic feeders: nutrients acquired by photosynthesis.
- store food as starch.
14
Q
Features of Animalia?
A
Over 1 million species.
- multicellular.
- nucleus, other membrane bound organelles.
- no cell walls, no chloroplasts.
- move with aid of cilia/flagella/contractile proteins (sometimes muscular organs)
- heterotrophic feeders: nutrients acquired by indigestion.
- food stored as glycogen.
15
Q
What are the recent changes to classification systems?
A
Originally were based on observable features.
Through study of genetics and biological molecules, scientists can now study evolutionary relationships which can be used to classify organisms.
- when organisms evolve, their internal and external features change along with dna. By comparing dna and proteins of different species, evolutionary links can be found.
16
Q
What classification system is currently used?
A
Three domain system- by Carl Woese. It groups organisms using differences: -in the sequences of nucleotides in the cells’ rRNA -cells’ membrane lipid structure. - cells’ sensitivity to antibodies. The system has 3 domains and 6 kingdoms.
17
Q
What are domains?
A
Further levels of classification at the top of the hierarchy.
18
Q
What unique form of rRNA and ribosomes do the organisms in the different domains have?
A
- Eukarya - 80s ribosomes, RNA polymerase contains 12 proteins.
- Archaea- 70s ribosomes. RNA polymerase contains 8-10 proteins.
- Bacteria- 70s ribosomes. RNA polymerase contains 5 proteins.
19
Q
What are the 6 kingdoms in Woese’s system?
A
Archaebacteria, Eubacteria, Protoctista, Fungi, Plantae, Animalia.
- prokaryotae kingdom becomes divided into two.
- although both archaebacteria and eubacteria are single celled prokaryotes. The chemical makeup is different.
20
Q
What is Archaebacteria?
A
- bacteria that can live in extreme environments.
Including; hot thermal vents, anaerobic conditions, highly acidic environments.
Eg. Thermophiles, Methanogens.
21
Q
What are Eubacteria?
A
- aka true bacteria.
- found in most common environments.
- most bacteria belong in Eubacteria kingdom.
22
Q
What is phylogeny?
A
The evolutionary relationships between organisms.
- it reveals which group a particular organism is related to and how closely they are related.
23
Q
What are phylogenetic trees?
A
Used to represent the evolutionary relationships. They are branched diagrams, showing different species have evolved from a common ancestor.
- earliest species = base of tree.
- most recent species = written at tips of the branches.
- closer branches= closer evolutionary relationships.
They are produced by looking at similarities/differences in physical characteristics and genetic makeup of species.
-Alot of evidence gained from fossils
24
Q
Advantages of phylogenetic classification?
A
- can be done without reference to Linnaean classification.
- classification uses knowledge of phylogeny to confirm groups are correct or cause changes.
- produces a continuous tree whereas classification requires discrete taxonomical groups.
- hierarchical nature of Linnaean classification can be misleading as it implies different groups in the same rank are equivalent.
25
What is evolution?
The theory that describes the way in which organisms evolve over many years as a result of natural selection.
- organisms best suited are more likely to survive and reproduce.
- characteristics are passed to offspring by genes in the dna.
26
What research did charles darwin carry out and findings?
- carried out observations on finches (bird type) in the Galápagos Islands.
- noticed that different islands had different finches. The birds were similar in many ways so therefore must be closely related. However, beaks and claws were diff shapes and sizes.
- he realised the design of beaks was linked to foods available on each island. - -Concluded that the bird with a beak best suited to that food will survive longer= so produces more offspring = passing on characteristics= all birds on that island have the same beak eventually.
- when he returned to England, he carried out experimental breeding of pigeons to gain evidence that his ideas may work.
27
Alfred Wallace?
A scientist who was developing his own evolution theory at the same time as Darwin.
- he sent his ideas to Darwin for peer review before publication. Found that their ideas were very similar so proposed a theory of evolution through a joint presentation.
- 1859 Darwin published “on the origin of species”. A book about the theory of evolution by natural selection.
28
Why was Darwins book controversial at the time?
- conflicted with religious views that God had created all of the animals and plants in their current form and only 6thousand years ago.
- Darwins theory also implicated that humans are a type of animal evolved from apes= conflicted with the strong held christian belief that God created man in his own image.
29
Evidence for evolution?
1. Palaeontology- study of fossils and the fossil record.
2. Comparative anatomy- study of similarities/differences between organisms’ anatomy.
3. Comparative biochemistry- similarities/ differences between chemical makeup of organisms.
30
How are fossils formed?
Formed when animal and plant remains are preserved in rocks.
- over long periods of time, sediment is deposited on the earth to form layers of rock. Different layers= different geological eras.
- within the different rock strata, the fossils are quite different.. they form a sequence from oldest to youngest, showing the gradual change over time.
This = fossil record.
31
What evidence do fossils provide?
1. Fossils from simplest organisms (bacteria) are found in oldest rocks. More complex organism (vertebrates) found in recent ones. Supports evolutionary theory that simple life forms gradually evolved into more complex ones.
2. Sequence in which organisms are found matches their ecological links to each other.
(eg. Plants before animal fossils shows animals require plants to survive)
3. By studying similarities in anatomy of fossils, can show how closely related organisms have developed from the same ancestor.
4. Allow relationships between extinct and living organisms to be investigated.
32
What are homologous structures and what do they provide evidence for? (Comparative anatomy)
A structure that appears different and may perform separate functions in different organisms but has the same underlying structure.
- the presence of homologous structures provides evidence for divergent evolution. This describes how different species have evolved from a common ancestor, each with a different set of adaptive features.
- this type of evolution occurs when closely related species diversify to adapt new habitats as a result of migration or loss of habitat.
33
Explain comparative biochemistry.
Is the study of similarities/differences in the proteins and molecules that control life processes.
- although these molecules can change over time, some are highly conserved among species. Small changes in these molecules can help identify evolutionary links.
- the hypothesis of neutral evolution says
use textbook??
34
What are the 2 types of variation?
Interspecific variation- variation between members of different species.
Intraspecific - differences between organisms within a species.
35
What two factors cause variation?
1. An organisms genetic material = leads to genetic variation.
2. Environment in which organism lives = leads to environmental variation.
36
Genetic causes of variation?
1. Alleles- with a gene for a particular characteristic, different alleles produce different effects.
2. Mutations- mutation in somatic (body) cells = only individual is affected. Mutation in gametes = passed on to offspring.
3. Meiosis- the genetic material inherited from the two parents is mixed up during independent assortment and crossing over. Leads to gametes of individual showing variation.
4. Sexual reproduction- offspring inherits genes from each parent so therefore differs.
5. Chance- during sexual reproduction, it is by chance as to which 2 gametes combine so individuals may differ from siblings.
37
Environment causes of variation?
- plants with greater access to sunlight grows more.
| - presence of scars as a result of accidents or disease which have no genetic origin.
38
link between environmental and genetic causes of variation.
In most cases, variation is caused by a combination of both environmental and genetic factors.
- eg. If you have genes to grow tall but have a poor diet you may only reach average height.
As many characteristics are affected by a combination of genetic and environmental factors, it is difficult to investigate the cause of variation = nature vs nurture argument.
39
Discontinuous variation and how is is represented?
A characteristic that can only result in certain values = shows discontinuous variation. There are no in between values.
- variation determined purely by genetic factors falls in this category. Eg. Human blood group, sex, bacteria shape.
Represented usually using bar chart. (Sometimes pie chart).
40
Continuous variation and how is it represented.
A characteristic that can take any value within a range = shows continuous variation.
- there is graduation from one extreme to the other for a characteristic= called continuum.
- characteristics often controlled by polygenes and influenced by environmental factors too.
Represented in a frequency table then plotted onto histogram. Curve drawn to show trend.
41
What is a normal distribution curve and its characteristics?
A bell shaped curve. The data is said to be normally distributed.
Features:
- mean, mode and median =same.
- bell shape is symmetrical about the mean. (50% value less than mean, 50% greater).
- most values lie close to mean value.
42
Standard deviation
A measure if how spread out the data is. Greater the SD = greater the spread.
- a characteristic with high sd has large amount of variation.
43
T-test
Used to compare the means of data values of 2 populations.
- to use this test, data must have a normal distribution and enough data should be collected to calculate a reliable mean.
- can use different sample sizes.
Paired data= paired t-test.
Unpaired data = unpaired t-test
44
Spearman’s rank correlation coefficient.
Used to consider the relationship between 2 sets of data.
| Can show a postive/negative correlation or no correlation.
45
What are adaptations and the 3 types?
Characteristics that increase an organisms chance of survival and reproduction in an environment.
1. Anatomical- physical features (internal/external)
2. Behavioural- way an organism acts. (Inherited/learned)
3. Physiological- processes that take place inside organism.
(One adaptation can fall into multiple categories^)
46
Anatomical adaptations?
- Body covering (hair,scales, spines, feathers)
- camouflage.
- teeth (shape and type)
- mimicry: copy other animals appearance/sounds to fool predators into thinking they’re harmless.
47
Behavioural adaptations.
- survival behaviour: opossum plays dead if it thinks its been seen .
- courtship behaviour: many animals exhibit courtship behaviour to attract a mate.
- seasonal behaviours: migration/hibernation.
These behaviours can be either learned of innate (inherited)
48
Physiological adaptations.
- poison production: many reptiles produce venom to kill their prey.
- antibiotic production: some bacteria produce antibodies to kill other bacterial species in the same area.
- water holding: water holding frog can store water in body, allowing it to survive in the desert to over a year.
- reflexes, blinking, temp regulation.
49
What are selection pressures?
All organisms are exposed to selection pressures. These are factors that affect the organism’s chances of survival or reproductive success.
Eg. Predation, competition, disease.
50
Stages of natural selection
1. Organisms within a species show variation in their characteristics due to genetic variation. (New alleles arising from mutation).
2. Organisms whose characteristics are best adapted to a selection pressure have increased chance of survival and successful reproduction. = survival of the fittest.
3. Successful organisms pass the allele encoding the advantageous characteristic onto their offspring.
4. This process is repeated for every generation. Over time the proportion of individuals with advantageous adaptations increases.
5. Over millions of years, this can often lead to the evolution of a new species.
51
What is convergent evolution?
Organisms from different taxonomic groups share similar anatomical features
They have analogous structures - features adapted to perform the same function but have different genetic origin.
E.g. - Marsupial Mole & Placental Mole (ON SPEC)
-In a placental mole the placenta connects the embryo to the mother's circulatory system in the uterus to nourish the embryo until it is mature at bith
-In a marsupial mole they leave and enter the marsupium (pouch) whilst still embryos
Complete development by suckling milk
52
What are the implications of evolution?
-Pesticide Resistance in Insects
Pesticides kill susceptible insects, some insects have resistance
They will reproduce and become more common with the resistive gene becoming more frequent in the gene pool
Insects will damage crop
-Antibiotic Resistance
Bio
flashcards
Decks in class (12)
# Cards
-
Chapter 2- basic components of living systems35
-
Chapter 11- Biodiversity38
-
C12- Communicable Disease28
-
Chapter 8- Transport In Animals72
-
Chapter 9- Transport In Plants52
-
Chapter 7- Exchange Surfaces+ Breathing43
-
Chapter 6 - Cell Cycle59
-
Chapter 10- Classification52
-
Chapter 4 - Enzymes33
-
3.8 - 3.11 Nucleic Acids32
-
Chapter 5 - Plasma Membrane26
-
Chapter 3 - Biological Molecules64
