Classification And Evolution Flashcards

(89 cards)

1
Q

What is classification?

A

It is the name given to the process by which living organisms are sorted into groups

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2
Q

What is the name of the classification system used by scientists?

A

The “Linnaean classification system” proposed by Carl Linnaeus in the 1700s

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3
Q

What are the 8 taxonomic groups?

A

They are Domain, kingdom, phylum, class,order,family,genus and species

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4
Q

Why do scientists classify organisms?

A

•To identify species and organism belongs to
• To predict characteristics
• To find evolutionary links- species in the same group probably share similar characteristics because they have evolved from a common ancestor

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5
Q

What is a species?

A

Species are defined as a group of organisms that are able to reproduce to produce fertile offsprings

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6
Q

What is Binomial nomenclature?

A

It is a system that is used to name organisms so that scientists all over the world know what organisms that are referring to during discussions

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7
Q

How to name organisms using the Binomial nomenclature?

A

The first word indicates the organism’s genus which is written in capital letter and the second word indicates the organism’s species which is written in lowercase letter

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8
Q

How were organisms originally classified into?

A

Organisms were originally classified based on two features, whether they moved(animals) or didn’t (plants)

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9
Q

What are the 5 kingdoms?

A

Protoctista
Prokaryota
Animalia
Plantae
Fungi

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10
Q

Who introduced the 5 kingdom classification system?

A

Robert Whittaker who was an American plant ecologist and he based it on the principles developed by Carl Linnaeus

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11
Q

Features of prokaryotae

A
  1. Circular DNA not wrapped around histone proteins
  2. They are unicellular
  3. They have no nucleus, nor membrane bound organelles
  4. They get their nutrients either by absorption through the cell wall or by photosynthesis
  5. They have small 70S ribosomes
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12
Q

Features of protoctista

A
  1. (mainly) Unicellular
  2. A nucleus and other membrane bound organelles
  3. Some have chloroplast
  4. Some move either with the aid of cilla and flagella or by amoeboid movement
  5. Nutrients are acquired through photosynthesis (autotrophic feeders), ingestion of other organisms(heterotrophic feeders) or both- some are parasitic
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13
Q

Features of fungi

A
  1. Unicellular or multicellular
  2. They are saprophytic feeders- nutrients are acquired by absorption mainly from decaying material
  3. No chloroplasts or chlorophyll
  4. A nucleus and other membrane bound organelles and a cell wall composed of chitin
  5. No mechanisms of locomotion
    6 most store their food as glycogen
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14
Q

Features of plantae

A
  1. They have chloroplast
  2. They are autotrophs- they make their own food through photosynthesis
  3. Their glucose storage molecule is starch
  4. They are immobile although gametes of some plants moved using cilia or flagella
  5. Their cell wall is made up of cellulose
  6. They have a nucleus and other membrane bound organelles
  7. They are multicellular
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15
Q

Features of animalia

A
  1. They are multicellular
  2. They have no cell wall
  3. They have a nucleus and other membrane bound organelles
  4. They have 80S ribosomes
  5. They are heterotrophs- they get their nutrients from eating other animals
  6. Their glucose storage molecule is glycogen
  7. They move with the aid of cilla, flagella or contractile proteins, sometimes in the form of muscular organs
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16
Q

Why were there changes to the classification system?

A

Through the study of genetics and other biological molecules, scientists were able to study the evolutionary relationships between organisms

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17
Q

Who and what was the new classification system?

A

Carl Worse proposed the new classification system which is known as the “3 Domain, 6 kingdom” system. It groups organisms using differences in the sequence of nucleotide in the cell’s ribosomal RNA

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18
Q

What are the three domains?

A

Archaea, Bacteria and Eukarya

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19
Q

Features of the Archaea domain

A
  1. They have 70S ribosomes
  2. Has circular DNA
  3. Has several types of RNA polymerase
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20
Q

Features of Bacteria Domain

A
  1. Has 70S ribosomes
  2. Have circular DNA
  3. RNA polymerase contains 5 proteins
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21
Q

Features of Eukarya domain

A
  1. Has 80S ribosomes
  2. Has linear DNA wrapped around histones
  3. RNA polymerase has 12 proteins
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22
Q

What are the 6 kingdoms using the Carl Woese classification system?

A

Plantae
Animalia
Fungi
Protoctista
Archaea bacteria
Eubacteria

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23
Q

Why isn’t the “Prokaryotae” part of this system?

A

In this system, the prokaryotae kingdom becomes divided into two -Archaea bacteria and Eubacteria

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24
Q

Explain why prokaryotes are now classified as two separate domains (3 marks)

A

This is due to the advancement in biological techniques which has enabled scientists to see differences in their chemical make-up with Eubacteria having peptidoglycan in their cell wall and Archaea bacteria don’t

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25
Describe how and why the classification systems have changed over time (6 marks)
Organisms were originally classified into two kingdoms based on major differences in characteristics (1) those that moved are animals and those that didn't are plants (1); scientific advances allowed smaller details to be observed (1); organisms divided into five kingdoms(1); plants, animals, fungi, protoctista, prokaryotes (1); Advances in science allowed DNA and proteins to be studied(1); provided evidence for evolutionary relationships (1); three domains system proposed by Carl Woese (1); relevant scientist mentioned (Linnaeus, Whittaker, Woese) (1)
26
What is phylogeny?
It is the name given to the evolutionary relationships between organisms. It reveals which group a particular organism is related to, and how closely related these organisms are
27
Features of a phylogeny tree
1. The oldest species are found at the base of the tree and the most recent species are found at the tips of the branches 2. The tips of the tree represent groups of descendent organisms(often species) 3. The nodes of the tree represent the common ancestor of those descendents. Two descendents split from the same nodes are called sister groups 4. The closer the branches of the tree are, the closer the evolutionary relationships between the species
28
Advantages of phylogenetic classification
1. It is not based on grouping organisms 2. The taxonomic classification treated the same taxon as equivalent which is misleading
29
What is evolution?
It is the theory that describes the way in which organisms evolve or change over many years as a result of natural selection
30
What is Darwin's theory of evolution?
Darwin believed that organisms with the most suitable characteristics to their environment are more likely to survive and reproduce, passing on those characteristics to their offspring which then becomes common in the population.
31
What are the 3 evidences for evolution?
1. Palaeontology: the study of fossils and fossil records 2. Comparative biochemistry: similarities and differences between the chemical makeup of organisms 3. Comparative anatomy: study of similarities and differences between organisms' anatomy
32
What is Palaeontology?
It is the study of fossils and fossil records
33
How are fossils formed?
They are formed when animals and plant remains are preserved in rocks.
34
What evidence do fossils provide?
1. They provide evidence that organisms lived ages ago and also how much or how little organisms have evolved over time, with different layers corresponding to different geological eras (the most recent layer being found at the top) 2. Fossils of the simplest organisms such as bacteria are found in the oldest rocks, whilst fossils of more complex organisms such as vertebrates are found in more recent rocks. This supports the evolutionary theory that simple life forms gradually evolved over an extremely long time period into more complex ones. 3. They allow relationships between extinct and living organisms to be investigated
35
Disadvantages of using fossil fuels
1. Fossil records are sometimes incomplete as many organisms are soft-bodied and decompose very quickly before they have a chance to fossilise as the conditions needed for fossils are not often present 2. Fossils that did form millions of years ago may have been destroyed by geological activity e.g. volcanoes, or may be undiscovered.
36
What is comparative anatomy?
This is the study of the similarities and differences in the anatomy of different living species
37
What are homologous structures?
They are structures that appear different and may perform different functions in different organisms, but have the same underlying structure
38
An example of homologous structures
An example is the pentadactyl limb of vertebrates. Even though these limbs have different functions (grasping, walking, swimming,flying), they all share a similar bone structure
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What does the similarity in structure indicate?
It indicates that all vertebrates have evolved from a common ancestor, therefore vertebrate limbs have all evolved from the same structure
40
What evidence do homologous structures provide?
They provide evidence for divergent evolution
41
What is divergent evolution?
This describes how from a common ancestor, different species have evolved each with a different set of adaptive features due to adaptation to a new habitat as a result of migration or loss of habitat
42
Example of divergent evolution
The finches that were studied by Darwin in Galapagos Island. The finches came from one ancestor but they had developed different beak shapes and sizes to eat different types of food
43
What is comparative biochemistry?
It is the study of the similarities and differences in the proteins and other molecules that control life processes.
44
What are the 2 common molecules that are studied?
1. Cytochrome C which is a protein involved in respiration and; 2. Ribosomal RNA
45
What is the hypothesis for neutral evolution?
The hypothesis for neutral evolution states that most of the changes in the structure of a molecule does not affect its function. This is because most of the changes occur outside of the molecule's functional regions. Since they have no effect on function, their accumulation is not affected by natural selection
46
How do scientists discover how closely related species are?
To discover how closely related species are, the molecular sequence of a particular molecule is compared. This is done by either looking at the order of DNA bases or at the order of amino acids in a protein. Species that are closely related have more similarities in their DNA and proteins.
47
What is variation?
It is the difference in characteristics between organisms
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Types of variation
1. Interspecific variation and; 2. Intraspecific variation
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What is interspecific variation?
It is the variation between members of different species and is often very significant
50
What is intraspecific variation?
It is the variation between organisms within a species
51
Causes of variation
1. An organism's genetic material 2. The environment in which the organism lives
52
Genetic causes of variation
1. Alleles (variations of a gene). 2. Mutations 3. Meiosis
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How does alleles cause genetic variation?
With a gene for particular characteristics different alleles produce different effects. Individuals in a species population may inherit different alleles of a gene
54
What is mutation?
This is a change to the DNA sequence and therefore to genes which can lead to changes in the proteins that are coded for. These protein changes can affect physical and metabolic characteristics
55
Where can mutations occur in the body?
1. In somatic (body) cells where just the individual is affected 2. In gametes
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What happens if mutations occur in gametes?
It may be passed onto the organism's offspring
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How does meiosis cause genetic variation?
Independent assortment and crossing over
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Environmental causes of variation
1. Climate 2. Diet 3. Accident
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Categories of variation
1. Discontinuous variation and; 2. Continuous variation
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What is discontinuous variation?
This is variation that is determined purely by genetic factors (a single gene) . These are characteristics that fall in clear cut categories with no in between values
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Example of discontinuous variation
1. Shapes of bacteria: they can either be rod shaped, comma, spherical, spiral or corkscrew shaped 2. Human blood group: it can either be O, A, AB, or B
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How is discontinuous variation normally displayed?
It is normally represented by a bar chart or pie chart
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What is continuous variation?
The difference in characteristics shows a complete range of measurements. The characteristics are usually controlled by many genes (polygenic) and the environment
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Examples of continuous variation
1. Height of plants 2. Mass of animals
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How is continuous variation displayed?
Data on continuous variation are called in a frequency table and are plotted on a histogram
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What are adaptations?
They are characteristics that increase an organism's chance of survival and reproduction in its environment
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What are the three categories of adaptation?
1. Anatomical adaptations 2. Behavioural adaptations 3. Physiological adaptations
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What are anatomical adaptations?
They are adaptations to the physical features (internal and external) of an organism.
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Examples of anatomical adaptation
1. Body covering such as scales, hairs, spines, feathers and shells. 2. Mimicry 3. Camouflage 4. Teeth
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How does mimicry help animals to survive?
Copying another animal's appearance or sounds allows a harmless organism to fool predators into thinking it's poisonous or dangerous. For example, the harmless hoverfly mimics the markings of a wasp to deter predators
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How does camouflage help animals survive?
The outer colour of an animal helps them to blend into its environment making it harder for predators to spot it. For example, the snowshoe hare is white in winter to match the snow and brown in summer to blend in with the soil
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Anatomical adaptations of plants
Marram grass is adapted to live in xerophytic conditions by having: 1. hairs on the inside surface of the leaves to trap moist air close to the leaf reducing diffusion gradient 2. Stomata sunk into pits which make them less likely to open and lose water 3. Thick waxy cuticles on the leaves and stems, reducing water loss through evaporation
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What are behavioural adaptations?
They are adaptations in how an organism acts or behaves which can either be inherited or learnt from their parents
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Examples of behavioural adaptations
1. Survival behaviours: rabbit freezes or an opossum plays dead when they think they have been seen 2. Courtship: many animals exhibit courtship behaviours to attract mates to increase their chance of reproduction. e.g scorpions 3. Seasonal behaviours: these adaptations allow organisms to cope with changes in their environment
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Examples of seasonal behaviours
1. Migration: this is when animals move from one place to another based on which environmental conditions are more favourable. e.g. for better climate or more food 2. Hibernation: this is a period of inactivity when an animal's body temperature, heart rate and breathing rate slow down to conserve energy reducing the animal's requirement for food. e.g. brown bears hibernate during the winter
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What are the two categories of behavioural adaptations?
1. Learned behaviour: these are behaviours that are learnt from experience or from observing other animals 2. Innate behaviour: this is behaviour that is inherited through genes
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What are physiological adaptations?
They are adaptations to the way an organism's biological processes function
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Examples of physiological adaptations
1. Poison production: many reptiles produce venom to kill their prey and many plants produce poison in their leaves to protect themselves from being eaten 2. Antibiotic production: some bacteria produce antibiotics to kill other species of bacteria in the surrounding areas
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What does anatomical adaptations provide evidence for?
It provides evidence for convergent evolution
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What is convergent evolution?
This is when unrelated species begin to share similar traits because the organisms adapt to similar environments or other selection pressures.
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What are analogous structures?
They are structures that have similar functions but different structures due to convergent evolution rather than shared ancestry
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Examples of convergent evolution
Examples are marsupials and placental mammals
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Convergent evolution in plants
Aloe and agave appear very similar as they have both adapted to survive in the desert. However, they have developed entirely separately from each other
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What are selection pressures?
They are factors that affect the organism's chance of survival or reproductive success
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What is natural selection?
All organisms are exposed to selection pressure. Organisms that are best adapted to their environment are more likely to survive and reproduce with the adaptations becoming more common in the population
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Steps in natural selection
1. Organisms within a species show variation in their characteristics that are caused by differences in their genes 2. Organisms whose characteristics are best adapted to a selection pressure such as competition for mate and resources or diseases, have an increased chance of surviving and successfully reproducing 3. Successful organisms pass the allele encoding the advantageous characteristics onto their offspring 4. Over time, the proportion of individuals with the advantageous adaptations increases. Therefore the frequency of allele that codes for this particular characteristics increases in the population's gene pool
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What is the gene pool?
These are alleles that are present in a population
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Modern examples of evolution
1. Antibiotic resistant bacteria: Methicillin resistant Staphylococcus aureus (MRSA) has developed to become resistant to many antibiotics. Bacteria reproduce very rapidly and so evolve in a relatively short time by altering their DNA or mutations. When the bacteria were exposed to the antibiotic, resistant individuals survived and reproduced, passing the advantageous allele for antibiotic resistance onto their offspring and over time, the number of resistant bacteria increased in the population
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Another example of modern evolution
Flavobacterium: They live in waste water from factories that produce nylon 6. Nylon 6 is used to make toothbrushes and violin strings. These strains of bacteria have evolved to digest nylon and are therefore beneficial to humans as they help to clear up factory waste. They are also useful for the bacteria as it provides them with another source of nutrients.