Module 4 Classification and evolution essential notes

Question 1

Describe biological classification

Answer 1

1. Classification is the grouping of items based their characteristics
2. Biological classification is the categorisation of organisms
3. Based on their biological features
4. Including anatomy, physiology, biochemistry and genetics
5. Into groups of similar species called taxonomic groups

Question 2

State the purposes of biological classification

Answer 2

1. Identification of species/unknown/newly discovered organisms
2. Characteristics of species in taxonomic groups can be predicted based on similarities
3. To determine evolutionary relationships between species (phylogeny)

Question 3

State the order of the taxonomic groups

Answer 3

1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. family
7. Genus
8. species

Question 4

Describe the three domains in biological classification

Answer 4

1. There are three domains
2. One domain that contains all the Eukaryotes (Eukarya)
3. And two prokaryotic domains
4. These are called the Archaea and Bacteria

Question 5

Describe the disadvantages of the using common names for organisms

Answer 5

1. Organisms may have more than one common name (including different languages internationally)
2. Different species may have the same common name
3. No information of the relatedness of organisms

Question 6

Describe the key features of the binomial naming system

Answer 6

1. The first part of the name is the genus of the organism
2. The second part of the name is the species
3. No two species can have both the genus and species the same
4. The genus should have the first letter capitalised
5. The species should be all in lower case
6. When hand-written, both parts of the name should be underlined

Question 7

State the names of the five kingdoms

Answer 7

1. Prokaryotae
2. Protoctista (eukaryotic)
3. Fungi (eukaryotic)
4. Plantae (eukaryotic)
5. Animalia (eukaryotic)

Question 8

State the key identifying features of the prokaryotae kingdom

Answer 8

1. Unicellular
2. Circular ‘naked’ DNA in cytoplasm
3. No membrane-bound organelles
4. Smaller ribosomes

Question 9

State the key identifying features of the protoctista kingdom

Answer 9

1. Eukaryotic
2. Unicellular
3. Contains membrane-bound organelles
4. Can have chloroplasts (autotrophic)
5. Absence of cell wall
6. Can be motile

Question 10

State the key identifying features of the fungi kingdom

Answer 10

1. Unicellular or multicellular
2. Eukaryotic
3. Contain membrane-bound organelles
4. Cell wall present BUT made of Chitin (polysaccharide)
5. Heterotrophic (no chloroplasts or chlorophyll)
6. Non-motile
7. Get nutrition by external digestion
8. Store glucose as glycogen

Question 11

State the key identifying features of the plantae kingdom

Answer 11

1. Eukaryotic
2. Multicellular
3. Contain membrane-bound organelles
4. Autotrophic
5. Carry out photosynthesis (so have chloroplasts)
6. Store glucose as starch

Question 12

State the key identifying features of the animalia kingdom

Answer 12

1. Eukaryotic
2. Multicellular
3. Contain membrane-bound organelles
4. No cell wall
5. Heterotrophic
6. So no chloroplasts
7. Cells can be motile (using cytoskeleton or flagella)
8. Glucose is stored as glycogen

Question 13

State the difference between original and modern methods of classification

Answer 13

1. Original classification was based only on observable characteristics
2. Partly due to limitations of technology
3. Modern classification is based on analysis of biological molecules (DNA, RNA, lipids)
4. DNA (gene), RNA base sequences can be compared
5. Protein structure and amino acid sequences can be compared
6. The structure of lipids can be compared
7. Organisms can be classified based similarity or difference on the above features

Question 14

State the key features of the three domains

Answer 14

Question 15

State the similarities between the domain and kingdom classification systems

Answer 15

1. Eukaryotic organisms are still separated from prokaryotic organisms
2. Both still have the four eukaryotic kingdoms (protoctista, fungi, plantae and animalia)
3. Both demonstrate the evolutionary relationships
4. Both have the taxons with the largest number of species at the top, and ending with taxons with single species at the bottom

Question 16

State the differences between the domain and kingdom classification systems

Answer 16

1. The domain system has more levels of taxons than the kingdom systems
2. The top level in the domain systems has a much greater number of organisms than the top level in the kingdoms system
3. The domain system separates prokaryotes into two types (Bacteria and Archaea), the kingdom system doesn’t
4. The domain system is more accurate as it takes into account molecular evidence as well

Question 17

Describe how phylogeny and classification are related

Answer 17

1. Phylogeny is the evolutionary relationship between organisms
2. Organisms evolve over time.
3. Genetic changes result in the development of particular protein and structural adaptations
4. Classification groups organisms based on the similarity of their adaptations
5. The classification should therefore reflect the evolutionary history of species
6. Organisms which are similar have a more recent common ancestor
7. Organisms which are very different have a more distant common ancestor

Question 18

Describe how to interpret a phylogenetic tree

Answer 18

1. The ends of branches represent existing individual species
2. The nodes represent common ancestors no longer in existence
3. The length of lines represent time
4. More similar species are close together (horizontally)
5. More similar species have more recent common ancestors
6. More distinct species are further apart (horizontally)
7. More distinct species have common ancestors further in the past

Question 19

Describe observations with which Darwin and Wallace came to form the theory of evolution by natural selection

Answer 19

1. There is variation within populations of organisms (they are not all the same)
2. Populations of organisms have to survive with limited resources, which causes a competition or struggle for survival, in which not all the members of the population survive to reproductive age
3. Offspring tend to develop the characteristics of their parents
4. (those that do survive, pass on their characteristics for adaptations)

Question 20

State the types of evidence for evolution

Answer 20

1. Paleontology (analysis of fossils)
2. Comparative anatomy
3. Comparative biochemistry

Question 21

Describe the key features of paleontology

Answer 21

1. Fossils are the preserved remains of organisms where geological conditions have prevented their complete decomposition
2. The depth at which fossils are discovered are related to the time since formation (oldest at the bottom, youngest at the top)
3. Simpler organisms such as bacteria and algae are found in the oldest rocks, more complex ones nearer the top
4. The sequence of fossils the rocks therefore shows their stage of evolution
5. Analysis of bones and other structural features can also be used to determine relatedness
6. Soft tissues will not be fossilised

Question 22

Describe the key features of comparative anatomy

Answer 22

1. This is the comparison of structural features of organisms
2. Usually this involves homologous structures (observable structures common to a number of different organisms, such as limbs)
3. These are analysed and compared to determine which organisms may be more closely and more distantly related

Question 23

Describe the key features of comparative biochemistry

Answer 23

1. This is the analysis of biological molecules such as DNA, RNA, protein and lipid
2. Adaptations of organisms developed in the evolutionary process are due to genetic changes affecting biological molecules
3. The sequences of bases in DNA can be compared
4. The sequences of bases in RNA can be compared
5. The sequences amino acids in proteins can be compared
6. However, the gene/RNA/protein being compared must be present the species being compared
7. Fewer differences indicate a more recent common ancestor

Question 24

State the main types and causes of variation in organisms

Answer 24

1. The variation in characteristics between different species is called interspecific variation
2. The variation in characteristics within a species is called intraspecific variation
3. Variation can be caused by:
4. Genetic factors
5. And environmental factors

Question 25

Describe the genetic causes of variation

Answer 25

1. Genetic variation is caused by the presence of different alleles for the same genes, and the various possible combinations of alleles
2. New alleles (for new characteristics) are created by the process of mutation
3. New combinations of alleles in offspring are produced as a result of meiosis (independent assortment and crossing over) and sexual reproduction

Question 26

Describe the environmental causes of variation

Answer 26

1. Some variation within the population is caused by environmental factors
2. These may affect members of the populations differently
3. For example soil quality and access to sunlight will affect the height of plants
4. Environmentally affected variation cannot be passed onto offspring

Question 27

Describe the features of discontinuous variation

Answer 27

1. Discontinuous variation is when there are only few distinct categories of a characteristic, for example blood type, or sex
2. Discontinuous variation is best represented by bar charts
3. Discontinuous variation is caused by the control of one or just a few genes
4. Discontinuous variation is less affected by environmental factors

Question 28

Describe the features of continuous variation

Answer 28

1. Continuous variation is when the characteristic can take any value within a range, such as height, or weight
2. Continuous variation is best represented by histograms, that show frequencies of particular ranges
3. Continuous variation is caused by the control of many genes
4. Continuous variation can also be caused by the significant influence of environmental factors

Question 29

Describe how populations with normal distributions can be described

Answer 29

1. Characteristics that show continuous variation have a normal distribution
2. Where there are very few individuals that have characteristics at both extreme ends, and most of the individuals are around the mean (bell shaped curve)
3. The spread of the population can be measured by the standard deviation (the bigger the standard deviation, the greater the spread, and the more unreliable the mean)
4. 99% of the population will be within three standard deviations either side of the mean (centre)

Question 30

Describe how populations with normal distributions can be compared

Answer 30

1. Normal distributions can be compared by comparing the means
2. The means can be compared using a t-test
3. The t-test compares the mean and standard deviations to two populations
4. And determines whether they are the same or significantly different

Question 31

Describe the steps involved in carrying out a t-test

Answer 31

1. Make a null hypothesis (there is no difference in the two means)
2. Calculate the mean and standard deviations for each of the two populations
3. Calculate the t test statistic using the equation
4. Determine degrees of freedom (DoF, (n1 + n2) -2))
5. Determine the critical value (CV) at 5% and the DoF
6. Compare the t value to the CV
7. If t > CV, reject null hypothesis
8. If t < CV, accept null hypothesis

Question 32

Describe how the correlation between two variables can be determined

Answer 32

1. If an environmental factor affects a characteristic the two may be correlated
2. Correlation between an environmental factor and an organisms characteristics can be confirmed using a Spearman rank correlation coefficient
3. Correlation values range from -1 to 1
4. 1 is a strong positive correlation, 0 is no correlation and -1 is a strong negative correlation

Question 33

Describe the steps involved in carrying out a Spearman rank correlation test

Answer 33

1. Make a null hypothesis (there is no correlation)
2. Assign ranks to each value in each variable
3. Calculate the r test statistic using the equation
4. Determine degrees of freedom (DoF, number of pairs of data)
5. Determine the critical value (CV) at 5% and the DoF
6. Compare the r value to the CV
7. If r > CV, reject null hypothesis
8. If r < CV, accept null hypothesis

Question 34

Describe the types of adaptations that can evolve by natural selection

Answer 34

1. Anatomical - structural and physical features
2. Behavioural - the way an organisms acts, inherited or learned
3. Physiological - the processes that occur inside the organism

Question 35

Give some examples of anatomical adaptations

Answer 35

1. Body coverings
2. Camouflage
3. Teeth
4. Mimicry
5. Marram grass xerophytic adaptations:
   
   1. Hairs on the inner side of leaves
   2. Sunken stomata
   3. Thick waxy cuticle

Question 36

Give some examples of behavioural adaptations

Answer 36

1. Can innate or learned
2. Survival behaviours
3. Courtship
4. Migration
5. Hibernation

Question 37

Give some examples of physiological adaptations

Answer 37

1. Temperature homeostasis
2. Production of toxins, venoms or antibiotics
3. Nervous systems

Question 38

Explain, with an example, convergent evolution

Answer 38

1. Convergent evolution is when very distantly related species evolve similar adaptations (analogous structures)
2. This occurs when the unrelated species occupy similar niches in their respective ecosystems
3. They face similar selection pressures
4. And so natural selection favours the evolution of similar adaptations
5. For example marsupial and placental moles are distantly related (as shown by the differences in their development)
6. But, they end up having similar adaptations

Question 39

Describe the process of evolution by natural selection

Answer 39

1. Populations of organisms have a range of characteristics due to genetic variation
2. Organisms face a struggle to survive due to competition, disease, predation or changing climate, called selection pressure
3. Many individuals die before reaching reproductive age.
4. Those with certain characteristics (genetic variations) survive and reproduce, passing on the alleles for adaptations to their offspring
5. Over many generations, these adaptations thus become more common in the population
6. The process continues resulting in gradual genetic change in the species

Question 40

Explain how pest resistance is developed

Answer 40

1. Insect populations have genetic variation, resulting some being more resistant to pesticides than others
2. The plant habitat of the insects may be treated with pesticides (the selection pressure), killing many before they can reproduce
3. The few resistant insects, now face less competition, and have a better chance of surviving and reproducing
4. Their alleles for their adaptation are passed onto their offspring, and become more common in the insect population
5. Over many generations, most of the insect population will become resistant to pesticides

Question 41

Explain how antibiotic resistance is developed

Answer 41

1. Abuse of antibiotics exposes populations of bacteria to a selection pressure
2. Many bacteria may be killed but due to genetic variation, some bacteria may have partial resistance
3. As many non-resistant bacteria are killed, there is much less competition for the remaining bacteria
4. Partially resistant bacteria can now freely reproduce, increasing the number of resistant bacteria
5. Continual exposure to the antibiotic will thus increase the level of resistance in the bacterial population