Classification And Evolution 4.3

Question 1

What is the binomial system?

Answer 1

-a system that uses the genus name and the species name to avoid confusion when naming organisms

Question 2

What is classification?

Answer 2

-the process of placing living things into groups

Question 3

What are the eight taxonomic levels in the current system of classification?

Answer 3

-Domain-> highest taxonomic rank. There are 3 domains
-Kingdom-> they are 5 main kingdoms.
-Phylum-> a major subdivision of the kingdom. A phylum contains all the groups of organisms that all have the same body plan e.g. possession of a backbone.
-Class-> a group of organisms that all possess the same general traits e.g. same number of legs
-Order-> a subdivision of class using additional information about the organism
-Family-> a group of closely related genera
-Genus-> a group of closely related species
-Species-> the basic unit of classification. All members of a species show some variations, but all are essentially the same

Question 4

What is a hierarchy ?

Answer 4

-smaller groups arranged within larger groups
-no overlap between groups
-classification systems are an example of a hierarchy

Question 5

How do you write a binomial name?

Answer 5

-write the genus name and, giving an upper case to the first letter
-then write the species name all in lowercase
-if written in printed text it should be in italics, if handwritten it is underlined

Question 6

What is the advantage of the binomial naming system?

Answer 6

-provides a universal name for the organism
-every scientist in every country will use the same name
-this avoids potential confusing caused by using common names

Question 7

What are the five kingdoms?

Answer 7

-Prokaryotae
-Protoctista
-Fungi
-Plantae
-Animalia

Question 8

What are some features of the Prokaryotae kingdom ?

Answer 8

-have no nucleus
-have a loop of DNA that is not arranged in linear chromosomes
-have naked DNA (DNA that is not associated with histone proteins)
-have no membrane-bound organelles
-have smaller ribosomes than in other groups
-have cells smaller than those of eukaryotes
-may be free-living or parasitic (some cause diseases)

Question 9

What are some features of the Protoctista kingdom?

Answer 9

-are eukaryotic
-are mostly single-celled (but many algae are multicellular)
-show a wide variety of forms (the only thing that all Protoctists have in common is that they do not qualify to belong to any of the other four kingdoms)
-show various plant-like or animal-like features
-are mostly free-living
-have autotrophic or heterotrophic nutrition- some photosynthesise, some ingest prey, some feed using extra cellular enzymes and some are parasites

Question 10

What are some features of the Fungi kingdom?

Answer 10

-are eukaryotic
-can exist as single cells (called yeasts) or they have a mycelium that consists of hyphae
-have walls made of chitin
-have cytoplasm that is multinucleate
-are mostly free-living and saprophytic- this means that they cause decay of organic matter

Question 11

What are some features of the Plantae kingdom?

Answer 11

-are eukaryotic
-are multicellular
-have cells surrounded by a cellulose cell wall
-are autotrophic (absorb simple molecules and build them into larger organic molecules)
-contain chlorophyll

Question 12

What are some features of the Animalia kingdom?

Answer 12

-are eukaryotic
-are multicellular
-heterotrophic (digest large organic molecules to form smaller molecules for absorption )
-are usually able to move around

Question 13

When scientists first began classifying organisms they relied solely on ….

Answer 13

Observable features

Question 14

How is cytochrome c used as evidence in classification?

Answer 14

-cytochrome c is a protein used in the process of respiration, all living organisms that respire have cytochrome c , but cytochrome c is not identical in every species.
-the amino acids in cytochrome c can be identified, if we compare the sequence of amino acids in the samples of cytochrome c from two different species , we can then draw conclusions:
-> if the sequences are the same, the two species must be closely related
-> if the sequences are different, the two species are not so closely related
-> the more differences found between the sequences, the less closely related the two species

Question 15

How is DNA is used as evidence in classification ?

Answer 15

-found in all living organisms
-DNA provides the genetic code, the code is universal (it is the same in all organisms) Meaning a particular sequence of DNA codes for the same sequence of amino acids acids in a bacterium as in any other organism
-mutations occur at random
-comparisons of DNA sequences provide another way to classify species, the more similar the sequence in a part of the DNA, the more closely related the 2 species
-if there are many differences, the species have evolved separately for a long time and they can be considered as less closely related
-this is probably the most accurate way to demonstrate how closely related one species is to another

Question 16

What is the three domain classification system?

Answer 16

-suggested by Carl Woese
-he based his ideas on detailed study of the ribosomal RNA gene
-the three domains consist of :
.Bacteria (eubacteria)- found everywhere and most bacteria within this kingdom
.Archaea (archaebacteria)- live in extreme environments
.Eukaryota
-organisms are split into these 3 domains based on the type of rRNA and ribosomes they have and the cell membrane structures

Question 17

Describe the domain Bacteria

Answer 17

Contains the kingdom Eubacteria only, found in all environments.
Prokaryotic unicellular organisms.
Distinct cell membrane lipids.
Have peptidogylcan (murein) in their cell walls.
Unique RNA polymerase enzyme.

Question 18

Describe the domain Archaea

Answer 18

Contains the kingdom Archaebacteria only, typically found in extreme environments.
Prokaryotic unicellular organisms.
Have histones so gene and protein synthesis is more similar to Eukarya than Bacteria.
No peptidogylcan in their cell walls.
Different cell membranes that contain fatty acids bound to glycerol by ether linkages.
Have a more complex form of RNA polymerase than Bacteria.

Question 19

Describe domain Eukarya

Answer 19

Contains four kingdoms from the five kingdom system: Animalia, Plantae, Fungi, Protoctista.
All have nuclei and membrane-bound organelles.

Question 20

What is phylogeny?

Answer 20

-the study of the evolutionary relationships between organisms

Question 21

Summarise Darwin’s conclusions

Answer 21

-there is a struggle to survive
-better adapted individuals survive and pass on their characteristics
-over time, a number of changes may give rise to a new species

Question 22

What is the difference between classification and phylogeny?

Answer 22

Classification is simply sorting organisms into groups. Phylogeny investigates the evolutionary relationships between organisms.

Question 23

How did Darwin and Wallace contribute to the theory of evolution?

Answer 23

-Darwin observed many different types of finch on the Galapagos Islands but he believed they must be related due to many similarities. He concluded a bird born with a beak more suited to the food available would be more likely to survive than one whose beak was less well suited. Those that survive pass the trait on to their offspring.
-Wallace had many similar ideas so they published their theory together
-Darwin then published his book ‘The Origin of Species’

Question 24

What is the evidence for evolution ?

Answer 24

-fossils-> looking at the remains of extinct organisms and comparing to those alive today. Dating the rocks can give a timeline to the changes seen

-comparing biological molecules

-DNA-> looking at the similarities and differences between DNA sequences in different organisms

Question 25

What is interspecific variation?

Answer 25

-variation/differences between species

Question 26

What is intraspecific variation?

Answer 26

-the variation between members of the same species

Question 27

What is continuous variation?

Answer 27

Continuous variation is when a characteristic can take any value within a range (such as height of animals). These are represented by histograms and usually display a normal distribution curve. These characteristics tend to be controlled by more than one gene and are often influenced by environmental factors.

Question 28

What is discontinuous variation?

Answer 28

Discontinuous variation is where there are no intermediates (such as the shape of bacteria as they are spherical, rod shaped, spiral or human blood groups). These are represented by bar charts. Most characteristics showing discontinuous variation are controlled by a single gene.

Question 29

What is an adaptation?

Answer 29

-a characteristic that enhances survival in the habitat

Question 30

What are anatomical adaptations?

Answer 30

-any structure that enhances the survival of the organism

Question 31

What are behavioural adaptations?

Answer 31

-an aspect of behaviour of an organism that helps it to survive the conditions it lives in

Question 32

What are physiological adaptations?

Answer 32

-an adaptation that ensures the correct functioning of cell processes
-they affect the way that the processes work

Question 33

Why might organisms from different taxonomic groups show similar anatomical features?

Answer 33

-since adaptions are selected by environment
-two unrelated species living in similar habitats may evolve similar adaptations, where those species adopt a similar lifestyle they mat evolve to look very similar
-this is known as convergent evolution

Question 34

Describe how natural selection works?

Answer 34

1. Random mutations occur within the population.
2. This introduces genetic variation to the population.
3. Whilst some mutations are harmful, sometimes new alleles created by mutations provide an organisms with an advantage to survive in their environment. Conditions within the environment which drive natural selection are called selection pressures (e.g. competition for resources, new diseases, new predators, changes to the climate).
4. The new allele provides a reproductive selective advantage. Therefore, the individuals with the allele are more likely to reproduce and pass the allele onto their offspring. These individuals have reproductive success.
5. Over many generations, there will be an increase in the frequency of this allele within the population.
6. Evolution is a change in the allele frequency of a population.

Question 35

How do pests develop a resistance to pesticides?

Answer 35

-a pesticide applies a very strong selection pressure
-if the individual insect is susceptible than it will die
-if it has some form of resistance then it may survive
-this will allow the individual with some resistance to reproduce and pass on the resistance characteristic, so the resistance quickly spreads through the whole population

Question 36

How may drug resistance in microorganisms develop?

Answer 36

-overuse of antibiotics
-incorrect use of antibiotics not finishing the prescribed course
->when you take antibiotics most of the bacteria are killed but there may be a few that are resistant to the antibiotic
->once most of the bacteria are killed you tend to feel better , so people may stop taking the antibiotic before they have finished the prescribed course
->this allows the resistant bacteria to survive and reproduce creating a resistant strain of bacteria