4.2.2 - Classification and Evolution

Question 1

What is phylogenetic classification?

Answer 1

It arranges species into groups according to their evolutionary origins and relationships. It tells us how closely related species are and how recent their shared common ancestors are.

Question 2

What is the order of the taxonomic hierachy from the largest taxon to the smallest?

Answer 2

• Domanin
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Question 3

What is the binomial system of naming species?

Answer 3

First name is genus and second name is species

Question 4

What is the advantage of the binomial system of naming species?

Answer 4

It is universal so the name is the same in every country and it can give an indication as to how closely related the animals are.

Question 5

What are the 5 kingdoms?

Answer 5

• Prokaryotae
• Protoctista
• Fungi
• Plantae
• Animalia

Question 6

What is prokaryotae?

Answer 6

• Unicellular
• No membrane bound organelles
• Small ribosomes
• Ring of DNA with no associated proteins
• Has no feeding system instead it absorbs nutrients across its surface or some photosynthesise

Question 7

What is protoctista?

Answer 7

• Unicellular
• Does have a nucleus and membrane bound organelles
• Sometimes have chloroplasts and some have cilia or flagella for movement
• Nutrients are absorbed either by photosynthesis, ingestion of other organisms or some are parasites

Question 8

What is fungi?

Answer 8

• Can be unicellular or multicellular
• Have a nucleus and membrane bound organelles
• No chloroplasts
• Cannot move
• Have a body made of threads or hyphae
• Nutrients can be absorbed from dead or decaying matter
• Food can be stored as glycogen

Question 9

What is plantae?

Answer 9

• Multicellular
• Have a nucleus and membrane bound organelles
• Have chloroplasts
• Don’t move
• Nutrients are absorbed by photosynthesis and food is stored as starch

Question 10

What is animalia?

Answer 10

• Multicellular
• Have a nucleus and membrane bound organelles
• No chloroplasts
• Can move using cilia, flagella or muscles
• Nutrients are obtained by ingestion and food can be stored as glycogen

Question 11

What did classification used to be based on?

Answer 11

It was based on observable characteristics which can be misleading as members of the same species can look very different if they live in different habitats with very different environment conditions. Members of different species can also look very similar if they share a habitat and are exposed to very similar environmental conditions.

Question 12

What evidence has led to new classification systems?

Answer 12

• DNA base sequence of organisms for common genes can now be compared as a measure of how closely related organisms are. The more closely related the species the higher the degree of similarity in the base sequences
• The sequence of amino acids in a polypeptide chain of proteins can also be compared because this sequence is determined by the sequence of DNA bases

Question 13

What are the 3 domains?

Answer 13

• Bacteria
• Archaea
• Eukarya

Question 14

What is bacteria?

Answer 14

• Have different membranes to archaea

Question 15

What is archaea?

Answer 15

• Often inhabit extreme conditions because they have adaptations in their cell membranes to withstand high temperature, pH and salt concentrations
• Very small in size, similar to bacteria or mitochondria

Question 16

What is eukarya?

Answer 16

• Have membrane bound organelles
• Divided into 4 kingdoms (Protoctista, Fungi, Plantae and Animalia)

Question 17

How did Darwin and Wallace contribute to the formation of the theory of evolution by natural selection?

Answer 17

• The idea was initially proposed by Wallace when he submitted his ideas to Darwin to be peer-reviewed
• Darwin had been aboard the HMS Beagle prior to this conducting his own studies into the theory with finches on each Galapagos Island
• As their ideas were so similar they worked together to publish scientific journals and then Darwin independently published ‘On the Origin of Species’

Question 18

What other evidence is there for the theory of evolution by natural selection?

Answer 18

• Fossils helped support the theory because they provide evidence of how species have changed over time and evolved
• By comparing DNA base sequences of common genes and other molecular evidence such as RNA or amino acid sequences we can examine how closely related different species are. This has enabled scientists to estimate the point in history when 2 species shared a common ancestor. Cytochrome C is a protein found in mitochondria which a large number of species have and it is often the protein that is compared.

Question 19

What is intraspecific variation?

Answer 19

Variation between individuals within the same species

Question 20

What is interspecific variation?

Answer 20

Variation between individuals in different species

Question 21

What is continuous variation?

Answer 21

• No distinct groups
• Quantitative differences in phenotype

Question 22

What are 2 examples of continuous variation?

Answer 22

• Mass
• Height

Question 23

What is discontinuous variation?

Answer 23

• Distinct groups
• Qualitative differences in phenotypes

Question 24

What are 2 examples of discontinuous variation?

Answer 24

• Blood group
• Eye colour

Question 25

What are environmental causes of variation?

Answer 25

The conditions in which an organism develops can cause variation. For example, intensity of light and the supply of water and nutrients will cause variation in the phenotype of plants

Question 26

What are genetic causes of variation?

Answer 26

- Mutation - a random spontaneous change in the base sequence of DNA - Meiosis - independent assortment of homologous chromosomes and crossing over - Random fertilisation of gametes - sperm and egg meet by chance contributing to unique combinations of alleles

Question 27

What are anatomical adaptations?

Answer 27

Internal or external physical features

Question 28

What are behavioural adaptations?

Answer 28

Changes in the ways organisms act

Question 29

What are physiological adaptations?

Answer 29

Processes that take place within an organism

Question 30

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

Answer 30

This is due to convergent evolution which is when different species are exposed to similar selection pressures so they undergo natural selection for similar alleles and therefore they become genetically similar. For example, the marsupial mole and the placental mole.

Question 31

How does natural selection affect the characteristics of a population over time?

Answer 31

- There is genetic variation in a population - Organisms with characteristics that allow them to survive will have a selective advantage when there is a new selection pressure and are more likely to reproduce so have higher reproductive success - Favourable alleles are passed onto the next generation - Those allele frequencies increase in the gene pool over many generations - This results in evolution

Question 32

What are 2 examples of how evolution in some species has implications for human populations?

Answer 32

- Evolution of pesticide resistance in insects which threatens the security of future food supplies - Drug resistance in microorganisms which has led to a reduction in the effectiveness of antibiotics