The importance of different types of relationships and interactions between other organisms

Question 1

topics

Answer 1

• relationships within ecosystems predator prey
• succession
• immunity - HIV
• nitrogen cycle

Question 2

relationships within ecosystems predator prey : The importance of different types of relationships and interactions between other organisms

Answer 2

• Predator and prey organisms interact in a variety of ways and it is their relationship which enable the population of both to prosper.
• Predator and prey populations go through healthy cycles where numbers rise and fall in accordance with the availability of prey and the level of predation, this keeps numbers of both populations at sustainable levels.
• This may be unregulated when there is a lack of predators, which leaves the population of prey unregulated.
• For example turtles in shallow waters graze on sea grass and when there are no sharks to introduce a predation pressure, single regions become overgrazed which reduces the amount of habitat and food available for other species in the area.
• Thus the presence of tiger sharks is beneficial to many organisms as they force the turtles to graze over a wider region which contributes to heterogeneity in ecosystems, preventing a single species from dominating and leading to better biodiversity.
• Ecosystems function and biodiversity benefits from a wide variety of predators and prey co-existing within the environment as this complex web of interdependency generates sustainable conditions for species to allow their populations to prosper.

Question 3

succession : The importance of different types of relationships and interactions between other organisms

Answer 3

• Organisms interact to create ideal abiotic and biotic conditions to sustain life in a habitat.
• When abiotic conditions are hostile, pioneer species can survive harsh abiotic conditions because they are specially adapted to and colonise the area.
• They change abiotic factors of their environment and when they die microorganisms decompose the dead organic material to form soil.
• Conditions become less hostile, so new organisms with different adaptations can move in and grow.
• Over time this allows more complex organisms to survive, and the ecosystem can reach a climax community where the soil is rich enough to support large trees or shrubs and the environment is no longer changing.
• Thus this increases the biodiversity of the area as the habitat becomes more occupied by species, this allows for the formation of more complex food webs due to high species diversity and therefore increased biomass.
• Therefore, the interaction between a pioneer species and decomposers can allow ideal abiotic environments to form to support a climax community.

Question 4

immunity : The importance of different types of relationships and interactions between other organisms

Answer 4

• Viruses cannot reproduce themselves as they have no cellular organelles like mitochondria or ribosomes, thus they have no metabolism and they are not capable of growth.
• As such, viruses rely on interactions with host cells if they are to reproduce.
• This can be seen in the instance of hIV where this invasive and harmful virus uses another organisms own processes for individualistic benefit.
• When HIV is introduced to the bloodstream in humans, it circulates until its attachment protein point to CD4 proteins on the target T-cells.
• The contents of the viral cell are injected into the host cell once the two membranes fuse.
• This includes reverse transcriptase enzyme from the virus which converts the virus’s RNA into DNA to allow it to be incorporated into the host cell’s own DNA.
• From here, the host cell’s DNA will be translated to form HIV viral proteins and cellular components.
• The cell membrane and lipid envelope reform around around the viral components and the HIV particles break away from the cell having been replicated.
• This shows how viruses capitalise on the reproduction process of other cells in order to be able to replicate themselves and thus sustain life.

Question 5

nitrogen cycle : The importance of different types of relationships and interactions between other organisms

Answer 5

• The nitrogen cycle shows the interdependency of organisms as without this process life for many organisms would be impossible since the first stage of the food chain begins with plants.
• The nitrogen cycle provides plants with nitrogenous compounds that they can use to be able to synthesise important building blocks such as DNA and protein.
• Firstly, via nitrogen fixation mutualistic nitrogen-fixing bacteria use the enzyme nitrogenous to reduce gaseous nitrogen into ammonia.
• Secondly, saprobionts feed on and decompose organic waste containing nitrogen to release NH3 gas which dissolves in water soil to form ammonium ions.
• Thirdly, anaerobic denitrifying bacteria convert soil nitrates back into gaseous nitrogen.
• The interaction of nitrogen fixing bacteria and saprobionts with plants allow access of nitrogen to plants, which they can use to synthesise chlorophyll, which absorbs light energy for photosynthesis.
• Without chlorophyll, the plant would be unable to photosynthesise to produce glucose which is contained in their cell membranes as cellulose.
• Therefore, the plant cell walls would be unsupported due to lack of cellulose and unable to withstand turgor pressure, turning them flaccid.