(The specifications referred to here are from the AQA Exam Board;
other Boards will of course differ slightly)
'3.2.4 The variety of life is extensive and this is reflected in similarities and differences in its biochemical basis and cellular organisation', specifically candidates should be aware that different organisms possess different types of haemoglobin with different oxygen transporting properties. They should be able to relate these to the environment and way of life of the organism concerned.
Find out about at the haemoglobin of the vent tubeworm Riftia pachyptila - how is it radically different to the haemoglobin of other animals, and why?
'3.2.8 Classification is a means of organising the variety of life based on relationships between organisms and is built round the concept of species',, specifically candidates should be able to appreciate the difficulties of defining species and the tentative nature of classifying organisms as distinct species.
Q: How many different types of animals do we find in the deep ocean, and at deep-sea vents? And what kinds of animals are they - what are the major groups?
When we encounter an animal at a depth of more than two miles in the ocean, there is a 50-50 chance that it is a new species. But what kinds of evidence do we need to collect to show that it is a new species?
'3.4.1 The dynamic equilibrium of populations is affected by a number of factors, specifically Populations and ecosystems: A population is all the organisms of one species in a habitat. Populations of different species form a community. Within a habitat a species occupies a niche governed by adaptation to both biotic and abiotic conditions.
Deep-sea vents are ideal examples of communities to use here, because they are relatively simple, with few species and contrasting niches. What are the populations that form the communities at deep-sea vents in the eastern Pacific? And in the Mid-Atlantic? The zonation of species around vents, with different species adapted to zones of different temperatures, is also a nice example of species occupying niches governed by adaptation.
'3.4.5 Energy is transferred through ecosystems and the efficiency of transfer can be measured', specifically Energy transfer: photosynthesis is the main route by which energy enters an ecosystem.
Q: How does energy enter the ecosystems at deep-sea vents? And where do deep-sea animals not living at vents get their energy from?
'3.4.6 Chemical elements are recycled in ecosystems. Microorganisms play a key role in recycling these elements'
Q: Where do the carbon and oxygen needed by life at deep-sea vents come from?
'3.4.7 Ecosystems are dynamic systems, usually moving from colonisation to climax communities in the process of succession', specifically Succession from pioneer species to climax community. At each stage in succession, certain species may be recognised which change the environment so that it becomes more suitable for other species. The changes in the abiotic environment result in a less hostile environment and changing diversity.
Deep-sea vents are ephemeral habitats, and provide some nice examples of succession, with pioneer species colonising new vent chimneys as those chimneys are built up by minerals precipitating from the vent fluids.
'3.4.8 Genetic variation within a species and geographic isolation lead to the accumulation of different genetic information in populations and the potential formation of new species', specifically Speciation: Geographic separation of populations of a species can result in the accumulation of difference in the gene pools. The importance of geographic isolation in the formation of new species.
Just as different species are found on different continents above the waves (e.g. lions in Africa, but tigers in India), we find different species at deep-sea vents in different parts of the world's oceans (e.g. different species of tubeworms at vents in the northeast Pacific, compared with vents in the tropical east Pacific).
Geographic isolation in the oceans forms new species to create these patterns of life, but this process is much less well understood than on land. This is one of the reasons that we study life at deep-sea vents: because they are like 'islands' on the ocean floor, they show us these patterns very clearly - just as islands above the waves did for biologists in the 19th century.
'3.1.3 Forces acting between molecules'
Q: Why is the hot water gushing from deep-sea vents still liquid at >360 deg C, rather than steam?
'3.2.4 Oxidation and reduction'
Q: What are the main dissolved metals in deep-sea vent fluids, and what happens to them when they mix with well-oxygenated seawater, as they gush out of the vents?
'3.2.11 Analytical techniques: mass spectrometry'
As an example, we use mass spectrometry to measure methane in seawater samples that we collect from the deep ocean, to help us pinpoint deep-sea vents.
'3.2.3 Waves: longitudinal and transverse waves', specifically characteristics and examples, including sound waves.
Q: How does sonar work, and what kinds of information can it give us about the ocean?
How can we use sonar, combined with the Doppler effect, to navigate our underwater vehicles relative to the seafloor?
'3.4.5 Magnetic fields'
We often measure variations in the magnetic field of the Earth's crust as we survey undersea volcanoes, using an instrument called a magnetometer. How does a magnetometer work, and what does it tell us?
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