Ecology

This topic, I hope, will spark interest as it is full of common sense ideas and knowledge that you can pull from everyday experiences. The basic needs in life are that plants need oxygen, carbon dioxide, light, water and nutrients. Animals need food, water and oxygen. Adaptations are the special characteristics that plants and animals develop to be better at surviving.

Plants adapt by having thorns or poisonous leaves to stop herbivores from eating them, animals may adapt by having teeth specific for their diet, camouflage, bigger feet to prevent sinking in sand or snow, claws for climbing or catching prey. There are many different and for this module, it is important that you research some.

Extremophiles are microorganisms that live in environments that would kill other organisms. One reason is that above a certain temperature, our enzymes stop working, they denature and so processes necessary for life cease. These Extremophiles have adapted to survive in these environments.

Artic fox

This arctic fox survives in a very harsh environment. It is successful because of its adaptations, examples of which are... Forward facing eyes allows for depth perception to see how far away prey is, if it is worth running for to conserve energy. White fur, prey cannot easily spot it. Big ears that rotate to listen for prey. Big feet that don't sink in the snow. Keen sense of smell and teeth specialized in killing animals and removing the meat.

Gentoo penguin adaptations

This Gentoo penguin cannot fly, it has adapted its wings for a better use...underwater swimming. Penguins can swim which is where they need to go to catch their food, they have strong legs and claws for climbing. They have very little blood circulation in their feet to reduce heat loss into the snow. They are white on the front so that when they are swimming, predators below see a pale colour which mixes with the sky and from above, they see the dark colour which looks like the deep ocean and they are hard to spot. They are streamlined for faster swimming and they have oily feathers to prevent the cold water reaching their skin.


Camel adaptations

The final "classic example" is the camel. Big feet, fat store, thick eyelashes and closing nostrils to keep out sand, it should be fairly obvious now what adaptations are but please do research further.


SIZE: the biggest impact that size of an animal has is its ability to lose heat. Big animals cool slowly and small animals cool faster. This is because of their "surface area to volume ratio". The ratio gets bigger as the animal gets smaller. Basically, in the cold, bigger animals keep warm easily - polar bears, seals etc and in hot climates, smaller animals cool down most easily - desert rats, scorpions, snakes.

Plants adapt and it may be more subtle. A cactus has huge spines to stop animals eating it to gain water. It also has a very thick cuticle to stop water evaporating whereas an oak tree doesn't need that, however, it is sunny all year around where cacti grow but oaks shed their leaves in the winter are they are of no use until spring and the tree shuts down for the season.

Animals have territory, an area where they find food and water, when more than one animal or pack are in the same territory, this creates competition. This may involve lions running another pride away or caterpillars adapting to look poisonous to scare predators away. Plants also compete and their adaptations vary for each plant or environment. Snow drops flower early so that they can get enough energy from the Sun before the trees above grow leaves and put them in the shade, others grow roots deeper than others to ensure they get most nutrients and water from the ground. Finally, seed dispersal varies widely, all are adaptations aimed at beating the competition.

The final section is about measuring our environmental impact. We can measure this by taking readings of temperatures of air and water chemicals in the air, water and soils etc. We also use living indicators such as populations of certain plants or animals. Have they increased, decreased, new species arrives, old species died out. When have species migrated, early, late, never returned, arrived for the first time. All of these are ways of measuring change. Certain lichens tell us about pollution levels. These specific organisms are called indicator species.

Biomass is simply the mass of anything that was once alive or still is. Pyramids of biomass show the mass of the population of organisms at that stage in a food chain or web.

This diagram below shows the reason that numbers of organisms are not as important as their biomass for the food chain:

Elder tree --> Aphids --> Lacewings --> Starling

Pyramids of numbers and biomass


The diagrams show that if you rely on numbers alone, the elder tree counts for very little in this eco system, however, when you account for the mass it has generated through photosynthesis as a producer, it is the largest part of the system.

Biomass transfer sankey diagram

In the above diagram, it begins to explain that all energy comes from the sun and producers use it to convert carbon dioxide and water into organic building blocks and energy. All of the aphids' energy comes from the tree and all of the lacewings' energy comes from the aphids and so on. Like all energy transfers, this is not particularly efficient, energy is lost along the way as shown in this Sankey diagram.

Carbon cycle

When animals eat plants or other animals, some of that energy is not passed onto their predators. For example, energy is used to generate heat, to move the animal, it is lost in inefficient digestion, repairing an sick animal, respiration processes and some of the animals die and are never eaten so their energy is lost in the decal process.


When organic material (plant or dead animal) is left, it will decay. This is the process in which organic matter is broken down. If this didn't happen, then the world would run out of nutrients. Detritus feeders like worms start the process by eating this material and breaking it part way down by producing its own waste. Decay organisms then complete the process by breaking it down all of the way. Decay organisms are much smaller than worms such as bacteria and fungi. This returns nutrients to the soil. Humans encourage this process in sewage treatment plants and in your compost heap at the bottom of your garden.


All of this decay is a part of the carbon cycle. Follow the cycle from an animal alive at the moment, see how it is breathing out carbon dioxide which is absorbed by plants to generate grass which the animal eats. When the animal dies, the decay process releases the carbon trapped in its tissues back into the atmosphere as carbon dioxide. The carbon dioxide will be absorbed by new grasses which will feed other animals and the cycle keeps repeating.
The balance of this cycle is altered by humans. When we cut trees down, we reduce the amount of carbon dioxide being reabsorbed from the atmosphere and when we burn that wood, we make matters worse by putting even more carbon into the atmosphere after reducing the planet's ability to remove it. To start this section, we revisit the topic of Photosynthesis.

Carbon dioxide + Water -> Oxygen + Glucose

Hydroponics: maximising photosynthesis

Please note that it is the exact reverse of respiration. Leaves have adapted for this purpose in the following ways, they have chloroplasts which contain chlorophyll, the place that photosynthesis takes place, they have a large surface area to capture as much Sun light as possible, they have hollow structures to allow for carbon dioxide to get in and they have veins which provide lots of water for the reaction.

The rate of photosynthesis is limited by the amount of carbon dioxide available, the amount and intensity of sun light and by temperature. As with many reactions, they get faster as they temperature goes up but as enzymes are involved, they are denatured and stop working after around 40°C.

When algae and plants have made this glucose, it is used in several ways. Most immediately, it is used for respiration in the cells where it is being produced. It can be converted into insoluble starch for longer term storage (iodine test). It may be converted into fats and oils for storage and finally, it may be turned into cellulose, proteins or fats to make new cell walls and membranes for new cells.

 We can get the best yield from our growing plants by using greenhouses and poly tunnels to raise the temperature and control the atmosphere around the plants. In these controlled environments, we can add more carbon dioxide or even replace soils with water that has the perfect mineral content for healthy growth called hydroponics.

It is not just green plants that have limiting factors, all life is limited by a few key factors that controls where on the planet they can live. These factors are: temperature, availability of key nutrients, the amount of light and liquid water and the availability of oxygen (respiration) and carbon dioxide (photosynthesis).



Key words and terms for this topic: adaptation, herbivore, carnivore, omnivore, extremophile, competition, territory, surface area to volume ratio, indicator species.Biomass, pyramid of biomass, solar energy, detritus feeder, decomposer, sewage, compost, carbon cycle, combustion, organic waste.glucose, variegated, limiting factor, photosynthesis, independent variable, dependent variable, mineral ion, nitrate ion, biomass, quantative sampling, transect, quadrat, range, mean, median, mode, valid, reliable, repeatable, reproducible.
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