Topic 7 - ecology

• An individual is part of a species, but lives in its habitat within a population.
• Many different populations interact in the same habitat, creating a community.
• The populations are often dependent on each other.
• An ecosystem is the interaction of a community with non-living (abiotic) parts of the environment.
• Organisms are adapted to live in the conditions of their environment.
• Organisms which need the same resources compete for it.
• There can be competition within a species or between different species.
• Plants may compete for light, space, water and mineral ions.
• Animals may compete for space, food, water and mating partners.
• Interdependence describes how organisms in a community depend on other organisms for vital services.
• These include for food, shelter and reproduction (pollination, seed dispersal), e.g birds take shelter in trees, flowers are pollinated with the help of bees.
• The removal or addition of a species to the community can affect the populations of others greatly, as it changes prey or predator numbers.
• A stable community is one where all the biotic (living) and abiotic (non-living) factors are in balance.
• As a result the population sizes remain roughly constant.
• An abiotic factor is a non-living factor.
• Abiotic factors which can affect a community: light intensity, temperature, moisture levels, soil pH and mineral content, wind intensity and direction, carbon dioxide levels, oxygen levels for aquatic animals.
• A biotic factor is a living factor.
• Biotic factors that can affect a community: food availability, new predators, new pathogens, competition.
• Organisms have adaptations that allow them to survive in the conditions where they live.
• To increase growth, livestock are also given high protein foods.
• Areas where livestock are kept have high temperatures so less energy is wasted on controlling body temperature.
• Herbivores do not have all the enzymes to digest all the material they eat, so it is egested instead.
• Lots of glucose is used in respiration, which produces the waste product carbon dioxide.
• Urea is a waste substance which is released in urine.
• Plants and algae transfer about 1% of the incident energy from light for photosynthesis, as not all the light lands on the green (photosynthesising) parts of the plant.
• Not all of the biomass eaten is converted into biomass of the animal eating it.
• Carnivores cannot generally eat bone, hooves, claws and teeth.
• Raising livestock in small cages so there is less movement and therefore less energy wasted on this is a farming technique to increase efficiency.
• The fungus Fusarium can produce mycoprotein, a protein-rich food source suitable for vegetarians, grown on glucose syrup in aerobic conditions, harvested and purified so it can be consumed, and produced without animals.
• Genetically modifying crops to have certain properties can have many advantages, such as modifying them to be resistant to pests or extreme weather conditions to increase yields, or modifying them to increase their nutritional value in places where they lack access to certain vitamins.
• Farmers aim to increase the amount of energy (from food) that is converted to biomass in livestock because this is more efficient.
• Not all biomass can be eaten.
• Only approximately 10% of the biomass of each trophic level is transferred to the next.
• This is done by reducing the energy transfer from the animals to the environment.
• Biomass consumed can be lost as faeces.
• Genetically modified bacteria produces insulin, which is taken and purified, and used to treat people with diabetes.
• Positive human interactions with ecosystems include maintaining rainforests, producing sulfur dioxide in factories which leads to acid rain, replanting hedgerows and woodlands, and clearing land in order to build on, maintaining the number of habitats.
• Pyramids of biomass show the relative biomass at each trophic level, with less biomass as you move up the trophic levels.
• Programs have been put in place to maintain biodiversity, including breeding programs to stop endangered species from becoming extinct, protection of rare habitats, reintroduction of hedgerows and field margins, and preservation of rainforests.
• Global warming refers to the fact that the temperature around the world is increasing due to the production of more greenhouse gases, resulting in more heat being absorbed and reflected back to Earth, heating it up.