Ecosystems:
An ecosystem is the space where living organisms interact with each-other and the non-living environments around them, creating a system. Physical surroundings, living things and non-living things the 3 main factors of an ecosystem.
A habitat is the place where an organism lives. A habitat provides all basic requirements for the organism’s survival: food, water, shelter and space. Food is needed for energy and growth. Water is needed is needed for growth, digestion, getting rid of waste and transporting valuable substances within the organism. Shelter is needed for protection against predators and space is needed for growth and reproduction of the species to ensure its survival.
Selection pressures are the external factors that can impact or influence an organism’s ability to survive. These pressures can negatively or positively impact the organism. There are 3 types of selection pressures: resource availability (sufficient food, habitat etc.) environmental conditions (temperature, weather conditions etc.) and biological factors (predators and pathogens). These pressures can either be density-dependant (population size) or density-independent (unaffected by population). Density-dependant factors may include: predators, availability of resources, supply of nutrients, disease or pathogen spread and accumulation of waste. Density independent factors may also include: Phenomena (natural disasters), abiotic factors and weather conditions.
Abiotic and Biotic factors are the two main components of an environment. Abiotic factors are the non-living things that influence the environment. This includes: water, fire, light, gas levels, temperature etc. Biotic Factors are the living things in the environment.
Predator/prey relationship: Where there is a predator (generally a carnivore) eating a prey. The top of the food chain is called an “Apex Predator”.
Symbiosis: where two organisms depend on each other, in order to survive
Parasites: Where only one organism benefits.
– A parasite is an organism that lives on or in another organism, that feeds on it without killing it.
– The parasite benefits whilst its host suffers.
– A similar group of parasites eventually cause death to their host. This often occurs by their young eating the host upon hatching.
Mutualism: Where both organisms benefit.
– Cow birds eat ticks and mites of large animals, the larger animal benefits from having parasites eaten by the bird and the bird gets a food source.
Commensalism: Sees one organism benefitting and the other unaffected
– Clownfish live in anemones without causing any harm to the anemone, the clownfish gets a shelter, whereas the anemone gets nothing.
Adaptations:
– Structural: A physical feature that equips an organism for survival its environment
– Behavioural: a feature of an organism’s habitat, action and way of live that equips an organism for survival in its environment
– Functional: A feature of the way an organism’s body works that equips an organism for survival in its environment. E.g. an animal’s camouflage
Producers: An organism that produces their own food. These are required from an ecosystem to survive to from chemical energy from the sun’s light. Also known as autotrophs from the Greek word “autos” = self, “trophe” = nourishing.
Consumers: Organisms that consume food. Consumers cannot produce their own food but rely on a chemical from of energy. A consumer’s food is initially made by the producer in some way. Also known as heterotrophs.
Types of consumers:
Herbivore: Eats plants (exclusively)
Carnivore: Eats meat (exclusively)
Omnivore: Eats everything
Detritivores: Eats small particles of dead animals and animal organic matter (waste) that accumulates as detritus. E.g. worms, larvae and snails.
Decomposers: Consumers that break down dead material. E.g. fungi and bacteria.
Photosynthesis:
Carbon Dioxide + Water Glucose + Oxygen (arrow represents light and chlorophyll)
Recycling Matter: Matter is what all things are made of. By matter we mean: elements (carbon, nitrogen and oxygen) or molecules (water). Matter is neither created nor destroyed. All matter cycles through the Earth cycles. Unlike the one-way flow of energy, matter is recycled within and between ecosystems. These cycles are Water Cycle, Nutrient cycle, Carbon cycle, Nitrogen Cycle and Phosphorous Cycle.
Parts of the Earth:
The earth system is divided into the atmosphere, hydrosphere, lithosphere, biosphere. The hydrosphere is the water, liquid, ice and vapour layer on the earth. The lithosphere the earth’s crust and upper mantle. The biosphere is the biotic and abiotic factors.
Biogeochemical cycles: the movement (or cycling) of matter through a system. Biogeochemical cycles are all part of the larger cycles that describe the functioning of the whole earth (not just the surface parts). Biogeochemical is when something is made up of biological, geological and chemical processes that help make the world go “round” and life exist on earth.
These cycles consist of:
– The Carbon and Nitrogen cycle: where the element enters the atmosphere at some point. The atmosphere acts as the major reservoir or store for the element.
– The Phosphorous Cycle: the element does not enter the atmosphere at any stage. Cycles are more localised. Soil or rocks act as the major store.
Genetics and Evolution:
Genetics:
Genotype: The genetic information on an allele for that trait is called genotype. Genotypes cannot be observed by genetic testing. Genotypes can be represented by letters to show the alleles and any variation that may occur. For example, B for brown or B for Blue Eyes.
Phenotype: When we see a characteristic, or trait, in an individual, we refer to this as the phenotype. Phenotypes are observable. For instance, Eye-Colour. If a phenotype is dominant, we represent this as a capital letter. If a phenotype is recessive, we represent this as a lower case.
Allele: The variation in genes. In our cells, chromosomes from homologous pairs that have the same length and have centromeres at the same position. Genes are located in the same position on the homologous chromosomes – these are called loci. Genes work in pairs to determine the characteristics shown but vary in what they express.
Homozygous: When we have two identical alleles on the same homologous pairs, we have homozygous alleles.
Heterozygous: When we have two different alleles
Evolution:
Evolution is the process by which modern organisms have descended from ancient ancestors. Evolution is responsible for both the remarkable similarities we see across all life and the amazing diversity of that life. Biological evolution, simply put, is descent with modification; lots of things happen over time, like trees losing leaves, but it is not an example of biological evolution.
Small scale evolution is the changes in gene frequency in a population from one generation to the next. Large scale evolution is the descent of different species from a common successor over many generations. Simply put, the accumulation of small scale evolution.
Heat Transfer:
Heat: the transfer of thermal energy from one object to another. The amount of heat in an object is measured in temperature, usually in the units of Celsius or Fahrenheit. Heat movies in three ways: radiation, conduction or convection.
Heat Transfer: occurs when thermal energy moves from an object with a higher temperature to an object with a lower temperature. Heat will continue to move until both objects reach thermal equilibrium. The amount of energy in the transfer is measured in joules. AS the temperature of an object increases, the particles inside move faster and begin to move away from each-other. As the particles move away, the object will expand in size. As the thermal energy leaves an object, the particles move closer together and the object will contract.