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Biodiversity + Evolution
Unit 2
Module 3…read more

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2.3.1 Biodiversity
· SPECIES ­ a group of individual organisms very similar in appearance, anatomy, physiology, biochemistry and genetics,
whose members are able to interbreed freely to produce fertile offspring.
· HABITAT ­ the place where an organism lives. Organisms are often very well-adapted to their habitat, especially if the
conditions are extreme.
· BIODIVERSITY ­ the variety of life, the range of living organisms to be found.
· Biodiversity is about the structural and functional variety in the living world ­ we can consider it at a number of levels:
­ The range of habitats where different species live.
­ The differences between species, all species are different from each other.
­ Genetic variation between individual belonging to the same species so we don't all look alike.
· In 2001, 2 organisations decided to work together to create the CATALOGUE OF LIFE - record all known species on Earth.
· They aim to cover all known species by 2011.
· By 2007 the annual checklist contained 1,008,965 species which is probably just over half the world's known species but this
is debateable.
· We cannot be sure how many species are on Earth because:
­ We cannot be sure we have found all the species on Earth.
­ New species are being found all the time.
­ Evolution and speciation are continuing.
­ Many species are endangered and some are becoming extinct.…read more

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2.3.2 Sampling Plants
· In order to measure the biodiversity of a habitat, you need to observe all the species present, identify them and count how
many individuals of each species there are ­ you can sample a habitat.
· You select a small portion of the habitat and study that carefully, then you multiply up the numbers of individuals of each
species found, in order to estimate the number in the whole habitat.
· Random sampling means studying a small part of the habitat and assuming it contains a representative set of species that
can be applied to the whole habitat. The sample sites must be chosen at random.
· You can count large plants individually but smaller plants may be too numerous to count ­ measure the percentage of
ground cover for these ones.
Random Quadrats
· A quadrat is a square frame used to define the size of the sample area ­ may be any size.
· You place the quadrat at random in the habitat.
· You need to identify plants within the frame then measure their abundance.
Using a Transect
· A transect is a line taken across the habitat.
· You take samples along the line.…read more

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2.3.3 Sampling Animals
Trouble with Animals
· Animals move and hide away.
· Any attempt to sample the animals in a habitat will disturb the habitat.
· To overcome this, you have to catch/trap the animals and then estimate the numbers from your trapped sample.
Sweep Netting
· Involves walking through a habitat with a net.
· You sweep the net through the vegetation in wide arcs - any small animals will be caught in the net.
· You empty the net's contents onto a white sheet to identify them.
· You have to be quick so they don't crawl/fly away.
· Can also use this method in water.
Collecting from Trees
· Spread a white sheet under a branch and knock the branch.
· Small animals are dislodged so you can identify them.
Pitfall Trap
· A trap set in the soil to catch small animals ­ small container in the soil so rim is just below the soil.
· Any animals moving through the plants/leaf litter on the soil surface will fall into the container.
Tullgren Funnel
· A device for collecting small animals from leaf litter.
· You place the leaf litter in a funnel, a light above drives the animals downwards as the litter dries out and warms up.
· They fall through the mesh screen to be collected in a jar underneath the funnel.
· Species Richness ­ the number of species found in a habitat. The more species are present, the richer the habitat.
· Species Evenness ­ the measure of the number of individuals in each species.…read more

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2.3.5 Classification + Taxonomy
· Biological classification is the process of sorting living things into groups.
· Natural classification does this by grouping things according to how closely related they are.
· Taxonomy is the study of the principles behind classification ­ the study of the differences between species.
· Species are usually grouped depending on how they look.
· Phylogeny is the study of how closely different species are related.
· The more closely 2 species are related, they closer they are on an evolutionary tree.…read more

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2.3.6 The 5 Kingdoms
· Have no nucleus + have a loop of naked DNA that is not arranged in linear chromosomes.
· Have no membrane-bound organelles.
· Carry out respiration on special membrane systems.
· Have a nucleus + mostly single-celled.
· Show a variety of forms with plant-like or animal-like features.
· The body consists of a mycelium ­ a network of strands called hyphae.
· The cytoplasm is surrounded by a wall of chitin (a polysaccharide).
· Multicellular.
· Gain their nutrition from photosynthesis ­ they are autotrophs.
· Have cells surrounded by a cellulose cell wall.
· Multicellular.
· Gain their nutrition by digesting + absorbing organic matter ­ they are heterotrophs.
· Usually able to move around.…read more

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