4.2.2 Classification and Evolution

Question 1

Phylogenetic Classification

Answer 1

Arranges species into groups according to their evolutionary origins and relationships
Tells us how closely related species are and how recent their shared common ancestors are

Question 2

Hierarchy

Answer 2

• Smaller groups arranged within larger groups
• No overlap between groups
  -Classification systems are an example of a hierarchy

Question 3

Binomial system

Answer 3

• Each species is universally identified using the binomial (two name)
• First name is Genus, second name is species

Question 4

5 Kingdoms

Answer 4

1. Prokaryotae
2. Protoctista
3. Fungi
4. Plantae
5. Animalia

Question 5

Prokaryotae (split between archaea + true bacteria)

Answer 5

• Unicellular
• No membrane-bound organelles, small ribosomes, ring of DNA with no associated proteins
• No feeding system - absorbs nutrients across its surface/some photosynthesise

Question 6

Protoctista (eukaryota)

Answer 6

• Unicellular
• Has a nucleus + membrane-bound organelles, sometimes have chloroplasts/some have cilia/flagella for movement
• Nutrients absorbed by photosynthesis. ingestion of other organisms or some are parasites

Question 7

Fungi (eukaryota)

Answer 7

• Unicellular or multicellular
• Have nucleus + membrane-bound organelles, no chloroplasts, cannot move, body made of threads or hyphae
• Nutrients absorbed from dead + decaying matter (saprobiants)
• Food can be stored as glycogen

Question 8

Plantae (eukaryota)

Answer 8

• Multicellular
• Have nucleus + membrane-bound organelles, have chloroplasts + don’t move
• Nutrients absorbed by photosynthesis + food stored as starch

Question 9

Animalia (eukaryota)

Answer 9

• Multicellular
• Have nucleus + membrane-bound organelles, no chloroplasts + can move using cilia, flagella or muscles
• Nutrients absorbed by digestion + food can be stored as glycogen

Question 10

Changes of classification systems

Answer 10

Advances in technology have improved accuracy of classification - advances in immunology + genome sequencing
- Classification used to just be based on observable characteristics
Can be misleading - members of the same species can look very different if they live in different habitats with different environmental conditions
- Members of different species can look very similar if they share a habitat + exposed to similar environmental conditions
- DNA base sequences:
Can be compared as a measure of how closely related organisms are
More closely related - higher similarity
Mutations accumulate over time, those species must have evolved from a common ancestor longer ago - more time to accumulate different mutations
Cytochrome C - protein found in many species
- Sequence of amino acids:
In a polypeptide chain of proteins can be compared - this sequence is determined by the sequence of DNA bases

Question 11

Carl Woese changes

Answer 11

• 3 domains added to classification system:
  Archaea, true bacteria, eukaryota
• Based on type of rRNA and ribosomes they have + cell membrane structures
• Eubacteria: found everywhere + most bacteria within this kingdom
• Archaebacteria: live in extreme environments - thermal hot springs + anaerobic environments

Question 12

Evolution

Answer 12

Change in allele frequency over many generations in a population
From natural selection
Darwin’s theory accepted now due to fossil, DNA + molecular evidence

Question 13

Anatomical adaptations

Answer 13

Adaptations are internal or external physical features

Question 14

Behavioural adaptations

Answer 14

Changes in the ways organisms act - can be genetic in cause or learnt from parents

Question 15

Physiological adaptations

Answer 15

Processes that take place within an organism

Question 16

Convergent evolution

Answer 16

When different species are exposed to similar selection pressures, then undergo natural selection for similar alleles + become genetically similar

Question 17

Intraspecific variation

Answer 17

Differences between members of the same species
Genetic variation within same species introduced through mutations, crossing over, independent assortment

Question 18

Interspecific variation

Answer 18

Differences between members of different species
Widest type of variation

Question 19

Natural selection

Answer 19

• Process that leads to evolution
• Results in species becoming better adapted to their environment
  1. Random mutation occurs
  2. Introduces genetic variation
  3. New allele provides organism advantage to survive due to selection pressure
  4. New allele provides reproductive selective advantage - more likely to reproduce + pass allele to offspring (reproductive success)
  5. Over many generations, increase in frequency of the allele within the population