Classification and Biodiversity

Question 1

1. What does hierarchical mean in classification?

Answer 1

Organised into discrete smaller groups contained within a larger group

Question 2

2. What is the hierarchy of taxons from largest to smallest?

Answer 2

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 3

3. What does phylogenetic mean?

Answer 3

Phylogenetic classification groups organisms based on their evolutionary relatedness

Question 4

4. Why is classification described as “tentative”?

Answer 4

The classification system is ever changing as scientific knowledge expands.

Question 5

5. What are the three domains?

Answer 5

Archaea
Eukaryota/eukarya
Eubacteria

Question 6

6. Which two of the domains contain prokaryotic cells?

Answer 6

Archaea and Eubacteria

Question 7

7. What feature of cells has been used to establish the relatedness of organisms into their domains?

Answer 7

Their ribosomal RNA in each domain share a distinctive and unique pattern

Question 8

8. What is an extremophile?

Answer 8

Organisms able to withstand extreme conditions e.g temperatures, pH’s, pressures

Question 9

9. Which of the 5 kingdoms have eukaryotic cells?

Answer 9

Animalia
Fungi
Plantae
Protoctisa

Question 10

10. What are the features of eukaryotes that distinguish them from prokaryotes?

Answer 10

Eukaryotes have membrane bound organelles and 80s ribosomes.

Prokaryotes do no not have membrane-bound organelles and have 70s ribosomes

Question 11

11. List distinguishing features of each of the 5 kingdoms.

Answer 11

Animalia:
- Nervous coordination
- Heterotrophic -> specifically Holozoic nutrition
- Lack cell walls
- Multicellular

Fungi:
- Heterotrophic -> Saprotrophic OR parasitic nutrition
- The cell wall is made of chitin
- Reproduce by spores or by budding

Plantae:
- Cell walls are made of cellulose
- Large central vacuole
- Autotrophic -> Photosynthesis

Protoctista:
- No tissue differentiation
- ALL have eukaryotic cells
- Can be Multicellular or unicellular

Prokaryotes:
- Prokaryotic cells (no membrane-bound organelles)
- Microscopic
- Circular DNA
- 70s Ribosomes
- Cell walls made of peptidoglycan

Question 12

12. Why are biochemical methods of assessing relatedness superior to using morphological features?

Answer 12

Morphological features can arise from convergent evolution, giving analogous features (same function but structurally dissimilar and from different origins). The same mutation occurred twice in separate ancestors that are not closely related due to the selective pressures of the environment.

Question 13

13. List 5 biochemical methods of establishing relatedness.

Answer 13

Immunological comparison:
- Antigens are injected from species A into species B to trigger antibodies.
- Blood sample taken from B with the antibodies and added to different blood samples from other species to see how well they recognise the proteins (Antigens) of other species.
- The more similar the species are to A, the more precipitate will form.
-

DNA hybridisation:
- Forming hybrid DNA: Isolate the DNA of two species and cut into fragments, and label one by attaching radioactive or fluorescent markers. Separate the initial double helix and mix together, hybrids will be 50% labelled.
- Separating: The amount of heating needed will determine how closely related they are.
- More heat = more hydrogen bonds = more complementary base pairings = more similar
- Less heat = Less hydrogen bonds = Less complementary base pairings = Less similar

DNA sequencing:
- Allows us to know the specific sequence of nucleotides.
- Align and then compare the similarities of the DNA sequences of organisms.
- Typically used to compare more closely related species because not all base changes will cause an amino acid change for them to be considered different enough to be another species.

Amino Acid Sequencing:
- Compares the amino acid sequence (primary structure) in a common protein between the tested organisms.
- Typically used to compare more distantly related species because not all base changes will cause an amino acid change for them to be considered different enough to be another species, so if there are many differences in amino acids this suggests a very different DNA sequence (more efficient than looking at every nucleotide if u already know the amino acids triplet codon is different).

DNA fingerprinting:
- Single-nucleotide polymorphisms (SNPs) are single-nucleotide differences in introns.
- Hyper-variable regions (HVR) are variable non-coding regions which are unique to the individual.
- Gel allows small fragments to move further, and the electrical charge causes the movement of the negatively charged fragments to the positive electrode.
- More similar banding patterns = more closely related

Question 14

14. Why are DNA base sequencing methods a better biochemical method than amino acid sequencing?

Answer 14

DNA base sequencing is more zoomed in as DNA is a degenerate code; not all base sequence changes will cause a change in amino acid. 64 Codons but only 20 amino acids.

Question 15

15. Define homologous and analogous and give an example of each.

Answer 15

Homologous: Features which arise from divergent evolution as they come from the same ancestor but are functionally different.
- Pentadactyl limb

Analogous: Features which arise from convergent evolution as they come from different ancestors but are functionally similar.
- Wings of a butterfly and a bat

Question 16

16. Define a species.

Answer 16

Organisms which can interbreed to produce fertile offspring.

Question 17

17. What does binomial naming mean?

Answer 17

• Universal naming system
• ‘Genus species’

Question 18

18. What taxons do the first and second names represent?

Answer 18

Genus
Species

Question 19

19. Where are the common ancestors located on a phylogenetic tree?

Answer 19

At branch points

Question 20

20. How could you use a phylogenetic tree to organise most closely to least closely related?

Answer 20

Species with more recent branching points/common ancestors are more closely related than those with distant common ancestors.

Question 21

1. Define biodiversity.

Answer 21

The number of species and the number of individuals within those species in a specified region.

Question 22

2. How does biodiversity vary between the two poles of the earth?

Answer 22

The poles are less biodiverse than the equator and tropics

Question 23

3. What does “biodiversity varies temporally” mean?

Answer 23

Biodiversity varies temporally – through time biodiversity has varied, e.g. mass extinctions reduce biodiversity.

Question 24

4. List the factors that can cause variation in biodiversity.

Answer 24

• Spatial/environmental variation: Bright environments = higher energy flow and greater biodiversity. High around the equator and tropics
  Bright environment with higher light intensity, so more plants grow here than low light intensity region. More energy flowing through an ecosystem produces more species and more individuals, thus higher biodiversity.
• Succession: The Community changes its habitat to be more suitable for its species, changing the community composition. Animal biodiversity typically increases while plant biodiversity decreases.
• Natural selection: Evolve to form new species whilst others don’t survive. Survival of the fittest
• Human factors: Pollution, deforestation, agriculture, and overfishing physically remove species or destroy their habitats. Farming has caused a monoculture to grow one crop to increase yield.

Question 25

5. What calculation is performed to assess biodiversity in a habitat?

Answer 25

Simpson's biodiversity index = 1−∑n( n − 1 ) / N( N −1) ∑n( n − 1 ) is the sum of number of n(n-1) of each species. N is the total number of organisms

Question 26

6. What are the two things that must be counted to do this calculation?

Answer 26

The number of species The number of individuals of each species

Question 27

8. What two number form the lower and upper limits of the calculation?

Answer 27

Lower = 0 Upper = 1

Question 28

9. How could you tell from the calculation that an area was more diverse than another?

Answer 28

Index values between 0 to 1, closer to 1 = more biodiverse

Question 29

10. Describe how you would sample two areas to get representative data.

Answer 29

Random Quadrat or Transect sampling for plants - Divide the two areas into 100 sections. - Measure plant diversity by counting no. plants per m^2. - Estimate mean % area cover - OR length of rope and measure at intervals along an environmental gradient by placing quadrats and counting Kick sampling and Simpson index for freshwater invertebrates: - Collect and identify from the given areas using a quadrat and net. - Kick or rake the two areas for a set period and collect downstream in the net. - Replace carefully, find means using both areas and then calculate Simpson's index. (For population size) Mark-release-recapture for terrestrial animals: - Capture and mark dont make them more visible to predators or harmed and then release. -Set traps 24 hrs later and catch individuals. - Population size = (no. in sample 1 * no. in sample 2) / no. marked in sample 2

Question 30

11. What is polymorphism?

Answer 30

The occurrence of more than one phenotype in a population that cannot be accounted for by mutation alone. Polymorphic genes (multiple alleles)

Question 31

12. How could you recognise genetic polymorphism in a species?

Answer 31

Gel electrophoresis (DNA fingerprinting) is the most commonly used procedure to detect these polymorphisms

Question 32

13. How would you assess genetic diversity in a species?

Answer 32

All members of the same species have the same genes, but can have different alleles. Variation in DNA base sequence. Different genotypes = different phenotypes. Greater number. different alleles in all members of a species = greater genetic diversity

Question 33

14. How can biodiversity be determined at a molecular level within a species?

Answer 33

DNA fingerprinting: - Single-nucleotide polymorphisms (SNPs) are single-nucleotide differences in introns. - Hyper-variable regions (HVR) are variable non-coding regions which are unique to the individual. - Gel allows small fragments to move further, and the electrical charge causes the movement of the negatively charged fragments to the positive electrode. - More differences in intron banding patterns = more variation/genetic diversity within species

Question 34

15. What feature would inform you that a species was genetically diverse?

Answer 34

Lots of differences in banding patterns

Question 35

16. How has biodiversity on the planet been generated?

Answer 35

Natural selection is the process in nature by which only the organisms best adapted to their environment tends to survive and transmit their genetic characters in increasing numbers to succeeding generations, while those less adapted tend to be eliminated. 4 stages of natural selection: - Mutation is the only process that produces new genetic material. * As more and more mutations occur within a population, its gene pool will change. - Variation exists between organisms. - Competition for resources due to selection pressures. * Best adapted have a selective advantage – outcompete others for resources. - Reproduction of the best adapted. * Pass on advantageous alleles to offspring.

Question 36

17. Give examples of organisms that are anatomically behaviourally and physiologically adapted to extreme environments like deserts and the arctic.

Answer 36

Anatomical: - Sharks have streamlined bodies - Some plants have flowers with honey or nectar guides called beelines to indicate the centre of the flower to attract pollinators. Physiological: - Hibernation: Mammals and birds are endothermic, so when it is cold, they have to try and avoid wasting energy to maintain body temperatures - Deciduous trees lose their leaves when temperature and light intensity decrease in autumn to minimise water loss and risk of dehydration when water may be frozen Behavioural traits: - Some animals perform mating rituals to increase the chances of reproducing. - Many plants flower in spring, when the pollinators have emerged, so they are pollinated. If they flower early or later, they do not get pollinated.