Biodiversity (complete)

Question 1

Define Species and Taxonomy.

Answer 1

• Species - a group of similar organisms that can reproduce and produce fertile offspring.
• Taxonomy - the science of classification:
  > naming organisms
  > organising them into groups based on their similarities.

Question 2

Name the levels of classification in order from largest to smallest.
Name the thee groups in the largest, and five groups in the second largest.

Answer 2

Domain (Bacteria, Archae, Eukarya)
Kingdom (Prokaryotes, Protoctista, Animalia, Plantae, Fungi)
Phylum
Class
Order
Family
Genus
Species

Question 3

Describe the difficulties with taxonomy.

Answer 3

• Species evolve over time
• Considerable variation can exist within a species.
• You can’t always see reproductive behaviours;
  > Species have become extinct with no fossil record.
  > They reproduce asexually.
• Practical and ethical issues;
  > different groups may be geographically isolated.
  > can’t study them in a lab.

Question 4

Name the two types of Classification.

Answer 4

• Artificial Classification.
• Phylogenic Classification.

Question 5

Define:
- Phylogeny.
- Artificial Classification.
- Hierarchy.
- Phylogenetic.
- Phylogenetic Classification.

Answer 5

• Phylogeny - the study of the evolutionary relationships of a group of organisms.
• Artificial Classification - dividing organisms into groups based on differences useful at the time (e.g: leaf shape, size, colour)
• Hierarchy - large groups are grouped into smaller groups with no overlap.
• Phylogenetics - tells us who is related to who and how closely related they are.
• Phylogenetic Classification - classifying species using shared features derived from common ancestors.

Question 6

Describe how you would name organisms according to the Binomial system of nomenclature.
What are the rules when writing the names?

Answer 6

• Latin/Greek names
• First name is generic name (Genus)
• Second name is specific name (Species)

Rules:
- Italics if printed, underlined if hand-written.
- First letter of generic name upper case.

Question 7

Describe Bacteria and their features.

Answer 7

• A group of single-celled prokaryotes.
  > the absence of membrane-bound organelles
  > unicellular, although cells may occur in chains or clusters.
  > ribosomes are smaller than in eukaryotic cells.
  > single loop of naked DNA made up of nucleic acids.

Question 8

Describe Archae and how they differ from bacteria.

Answer 8

• A group of single-celled prokaryotes originally classified as bacteria.
  Differ because:
  > their genes and protein synthesis are more similar to eukaryotes.
  > their membranes contain fatty acid chains attached to glycerol by ether linkeages.
  > there is no more in in their cell walls.
  > they have a more complex form of RNA polymerase.

Question 9

Describe Eukarya and their features.

Answer 9

• A group of organisms made up of one or more eukaryotic cells, split into four kingdoms (protoctista, plantae, animalia, fungi)
  > their cells posses membrane-bound organelles.
  > they have membranes containing fatty acids chains attached to glycerol by ester linkeages.
  > not all posses cells with a cell wall, but where they do they contain no murein.
  > ribosomes are larger than in bacteria and archae.

Question 10

Define:
- Biodiversity
- Species richness
- Species diversity
- Genetic diversity
- Ecosystem diversity

Answer 10

• Biodiversity - describes energy in the living world.
• Species richness - the number of different species.
• Species diversity - the number of different species and the abundance of each species within a community.
• Genetic diversity - the variety of genes possessed by individuals that make up only one species.
• Ecosystem diversity - the range of different habitats within a particular area.

Question 11

Describe how species diversity can affect the stability of an ecosystem and how it’s affected by climate change.

Answer 11

• The higher the species diversity, the more stables the ecosystem and the less it’s affected by climate change.

Question 12

Define:
- Population
- Ecosystem

Answer 12

Population - the number of the same species in the same area.
Ecosystem - all of the living and non living components of an area.

Question 13

Describe biodiversity in harsh environments.

Answer 13

In extreme environments, the species diversity is normally low, only a few species will have the necessary adaptations to survive.
Here the ecosystem in unstable and dominated by climate factors rather than the organism within the community.

Question 14

Describe biodiversity in less harsh environments.

Answer 14

• The species diversity is normally high in a habitat such as a rainforest.
• Here the ecosystem is stable and dominate by living organisms rather than the climate.

Question 15

Describe how the species diversity of plants/producers in an area can affect the species diversity of insects, animals and birds.
Why is this?

How do you calculate species diversity. What can the size of the species diversity value tell you?

Answer 15

• The higher the species diversity of plants/producers in the area the higher the species diversity of insects, animals and birds.
• This is because there are more habitats, there is a large, more varied food source.

Species diversity = (N(N-1)) / sum of (n(n-1))
(where N = total number of organisms of all species and n = total number of one species)
- The higher the number, the more diverse the area is.

Question 16

Why is courtship behaviour necessary in organisms?

Answer 16

• It enables individuals to:
  > recognise members of their own species (in order to produce fertile offspring).
  > Identify a mate that is capable of breeding (needs to be sexually mature, fertile and receptive).
  > Choose a strong and healthy mate.
  > Approach each other closely without triggering aggression.
  > Form a pair bond and synchronised mating (leading to successful mating and raising of offspring.

Question 17

Why do males perform such elaborate and prolonged courtship displays?

Answer 17

• Female needs to be sure the male is of the right species.
• Male needs to know she is receptive, and eggs are ready.
• The quality of the display may make the female more likely to choose a particular mate.

Question 18

Name the beneficial reasons for maintain biodiversity.

Answer 18

• Ethical; humans have a responsibility to reduce their impact on the plant and other species.
• Ecological; biodiversity increases the stability of ecosystems.
• Environmental; organisms provide essential environmental services.
• Economic; a range of organisms contribute to medicine, science, ecotourism and technology.
• Aesthetic - humans take pleasure from the visual effects of biodiversity.
• Agricultural - genetically diverse wild species can rescue crops from catastrophes.

Question 19

What is the impact of deforestation on biodiversity.

Answer 19

• Deforestation destroys habitats, causing some species to lose their shelter and/or food source. This will mean these species will either die or be forced to migrate to another area.
• This causes a loss/reduction in biodiversity.

Question 20

What is the impact of agriculture on biodiversity. (give examples)

Answer 20

• Farmers constantly to maximise the yield they can produced from a given area of land.
  > woodland clearance; to increase farmland area.
  > draining ponds and installing drainage systems.
  > hedgerow removal; to increase farmland area.
  > monoculture (grow fields with one type of crop).
• These all reduce biodiversity in the area.
  > Pesticides; reduce diversity by directly killing pests and indirectly harming/killing the species that feeds on the pests.
  > Herbicides; reduce plant diversity by killing weeds and indirectly killing/harming the organisms that feed on them.

Question 21

Describe Artificial vs Natural fertilisers and their effects.

Answer 21

Artificial - made up of inorganic matter in the form of powdered or pellets that contain pure chemical components/ions.
- As the exact chemical composition is known, it’s easier to know how much to apply and the effects.
- Nutrients are more highly concentrated so small amounts are needed.
Natural - made up of organic matter in the form of dead and decomposing remains of organisms and their waste products.
- They can help improve soil structure, which helps reduce soil-erosion and increase water-holding ability.
- Nutrients from natural fertilisers are released over long time periods, and in small amounts so lots are needed.

Question 22

Describe how to investigate diversity by comparing observable characteristics.
What are the limitations?

Answer 22

• Each observable characteristic is determined by a gene or genes.
• The variety within a characteristic depends on the number and variety of alleles of that gene (plus environmental influences)
• Limitations:
  > observable characteristics are polygenic, meaning a large number of them are coded for by more than gene, meaning they vary continuously.

Question 23

Describe how to investigate diversity by comparison of DNA base sequence.

Answer 23

• Using gene technology to read the base sequence of an organism, to compare the nucleotide sequences of two species/organisms to show how similar/different their DNA is.
• DNA sequencing (along with various techniques) can help us accurately determine the exact order of nucleotides on DNA.
• Comparison can also be done between organisms of the same species to determine how diverse they are.

Question 24

Describe the process of DNA sequencing.

Answer 24

• Using computerised systems to tag each nucleotide base in the base sequences of DNA with fluorescent dye.
• This produces a series of coloured bands representing the four nucleotide bases.
• This allows us to measure the genetic diversity of a species by sampling the DNA of its members and produce a pattern of coloured bands.

Question 25

How could you compare DNA of organisms without sequencing it?
How can you tell that a species is closely related by this method?

Answer 25

DNA Hybridisation:
- Taking two DNA samples of different organisms, that have been labelled using fluorescent or radioactive marker.
- Applying heat to break the weak hydrogen bonds between bases.
- Mixing and cooling the different single strands, allowing bonds to form between the bases.
- The more closely related the two organisms/species are;
> the more base pairing
> the more hydrogen bonds form, (higher temperature required to separate the strands).

Question 26

Describe how to investigate genetic diversity by comparing mRNA of organisms.

Answer 26

• The base sequence on mRNA are complementary to those of the strand of DNA from which they were made.
• mRNA can be extracted and compared in different individuals by looking for similarities in the base sequence.

Question 27

Describe the two ways of how to investigate diversity by comparison of proteins in organisms.
How can this show how closely related a species is?

Answer 27

Similar organisms will have similar proteins in their cells. These can be compared by:
> Comparison of amino acid sequences;
- the sequence of amino acids in proteins is determined by DNA.
- the degree of similarity in the amino acid sequence of the same protein in two species will therefore determine how closely related they are.
> Immunological comparisons;
- similar proteins will bind to similar antibodies.
- Serum containing antigens from Species A (e.g: human) is injected into Species B (e.g: rabbit), who produces antibodies in response to antigen. The serum is then added to Species C where the antibodies bind to the corresponding antigens of Species C producing a precipitate.

• The greater the number of similar antigens:
  > the more precipitate formed
  > therefore the more closely related species A is to species C.

Question 28

Define Intraspecific variation vs Interspecific variation.

Answer 28

Intraspecific variation - Variation between members of the same species.
Interspecific variation - Variation between two different species.

Question 29

What issues can arise from random measurements taken not being representative of the whole population?

Answer 29

• Sampling Bias; the selection process may be biased or the investigators may be making unrepresentative choices deliberately or unwittingly.
• Chance; even is sampling bias is avoided, the individuals chosen may be, by pure chance, not representative.

Question 30

Describe how you would carry out random sampling.
What can be done to minimise the effect of chance on the sampling process?

Answer 30

• Divide the study area into a grid of numbered lines.
• Using random numbers, generated from a table or computer, obtain a series of co-ordinates.
• Take samples at the intersection of each pair of co-ordinates.
• Using a large sample size - the more individuals selected, the smaller the probability that chance will influence the result, and the less influence anomalies will have, therefore the more reliable the data will be.
• Analysis of the data collected using statistical tests - to determine the extent to which chance may have influenced the data. These tests will allow us to decide whether any variation observed is the result of chance or is more likely to have some other cause.

Question 31

When would you use a t-test statistical test?

Answer 31

• When comparing the mean of data sets/histograms
• When calculating/comparing significant difference between data.