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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




2.3.1 Biodiversity
Biodiversity: The number and variety of organisms found within a specified ecosystem or
biome.

Species: A group of living organisms consisting of similar individuals capable of exchanging
genes or interbreeding. The principal natural taxonomic unit.

Habitat:…

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




o Quadrat is placed at random on the habitat and the
plants within the quadrat are identified.
o Abundance is then measured in one of three ways:
Abundance scale ­ Each species in the quadrat
has an abundance…

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




Species Richness & Evenness
Species richness: The number of species found in a sample area

Species evenness: How evenly distributed the number of individuals are between the
numbers of species present

Estimating richness
A qualitative survey can be…

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




High SID values indicate a diverse habitat ­ small change may affect one species, habitat
therefore able to withstand change, it is stable;
Low SID values suggest habitat dominated by a few species ­ small change could
damage/destroy…

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




Mostly free living
Have autotrophic or heterotrophic nutrition

Fungi ­

Eukaryotes
Have mycelium which consists of hyphae
Walls made of chitin
Cytoplasm is multinucleate
Mostly free living and saprophytic

Plantae ­

Eukaryotes
Multicellular
Cells surrounded by a cellulose…

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




Organisms are named using the binomial system - using two names: the genus name and
the species name, e.g. Homo sapien, which can be abbreviated to H. sapien. It is always
italicised (underlined when handwritten), and the genus…

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




Flagella with a different internal structure
Different enzymes for building RNA
No proteins bound to their genetic material
Different mechanisms for DNA replication and building RNA

Archea share certain features with the Eukaryotae:

Similar enzymes for building RNA…

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




Genetic Variation: Our genes define our characteristics - we inherit a
unique combination of alleles from our parents. We may share many
alleles and genes with others in our species; however as there are
approx. 25,000 genes (many…

Page 9

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




Over time, a number of changes may give rise to a new species

Natural Selection: The `selection' by the environment of particular individuals that show
certain variations. These individuals will survive to reproduce and pass on their variations…

Page 10

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Unit F212: Molecules, Biodiversity, Food & Health Module 3: Biodiversity & Evolution




The problem with fossil evidence is that it's incomplete. Usually only
the hard parts of an organism become fossilised and not all organisms
have hard parts. Fossils also only form under certain conditions.
Molecular Evidence
If one species…

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