Bio Ecosystem Revision PDF

Biodiversity -- the array of living organisms within an ecosystem, including species, genetic, and ecosystem diversity. 1% of sunlight is trapped and converted to chemical energy by producers. Energy is lost along theway as heat energy as organisms respire carbohydrates for their energy provision....

Biodiversity -- the array of living organisms within an ecosystem, including species, genetic, and ecosystem diversity. 1% of sunlight is trapped and converted to chemical energy by producers. Energy is lost along theway as heat energy as organisms respire carbohydrates for their energy provision. 90% of energy is lost at each trophic level due to them using it for life processes such as making new tissue, making the process inefficient. Population: all organisms of the same species that inhabit a particular area at the same time. Community: Multiple **different** populations, interacting within the **same location.** **Ecosystem:** Community of living things interacting with each other and the physical environment, both biotic and abiotic factors are present. **Key threats to biodiversity:** - Habitat fragmentation - Climate change - Introduced species / pathogens - Agriculture **Social and ecological implications of climate change:** - Melting of glaciers = raised sea levels - Rising water temperatures = ocean acidification - Growth in insect populations - Changes in wind systems = more frequent floods, droughts, hurricanes and forest fires. Factors affecting species survival: - Interactions between species (same/ different species) - Availability of resources - The weather climate - Impact of human activities. Zonation: the division of an ecosystem into hjorziontal distinct zones due to abiotic conditions. Pattern of zonation -- different species have different tolerances to one or more abiotic factors. Each species is adapted to the zone they live in to survive and reproduce. Species rarely leave their area unless environmental conditions change. Stratification: organisation of vegetation in vertical layers based on height. Competition: When organisms are in competition for the same resource, the strongest and best adapted organisms succeed, can happen between the same or different species. Predation: one organism is hunted and killed, prey -- victim, predator- attacker Symbiosis: Parasitism: one species live on/ in another organism. The host is negatively affected. E.g a tick on a kangaroo. Mutualism: both species between from another e.g a remora fish cleaning shark's mouth (food, and shark gains food itself.) Commensalism: one species benefits, the other is unharmed, e.g. a barnacle attaches to a razorfish. Psychological adaptation: internal responses to external stimuli, the body can function differently to survive in an environment. e.g hibernation where the cold temperature change causes the body to release hormones triggering sleepiness, leading to slowed metabolism with lowered body temperature and breathing rates. Here the bear uses body fat reserves to converse energy until spring hits and a food source can be used. : behavioural adaptation assisting in the survival of organisms in an ecosystem. - Nocturnal - Maternal/paternal care - Mating rituals - Group living: organisms can avoid/ intimidate predators and have a greater opportunity to discover and control food sources. Niche -- 1. The role that a population plays in the life of the community 2\. All the abiotic and biotic factors a particular species needs to survive and reproduce in an ecosystem, includes physical, chemical and biological factors. Keystone species: a species whose influence on an ecosystem is greater than their numbers. Their presence or absence can significantly affect other species in the ecosystem. E.g. sea otters eat sea urchins which would destroy kelp forests, kelp forests are an important habitat for high numbers of species diversity and they help fight beach erosion. Succession: the gradual process of which the composition of species changes over time. Primary succession: new environment with no living things, pioneer organisms alter the environment due to their life process (e.g. lichen turning rock into soil). These changes allow other species to be introduced as the conditions are more favourable, leading to a change in the mix of species in the environment. Secondary succession: occurs in a well-established ecosystem when a disturbance (Fire, flood) impacts the species composition. Not all species are destroyed, some species can regenerate faster than others altering the environment, and new environmental factors may favour new species, leading to a new mix of species. Fire -- can clean out overgrown plants, it also can be a stimulant for the germination of some plants, the destruction of much plant life, enables new species to establish themselves. Pioneer organisms' life processes: alter the environment due to their life processes, making it more favourable to introduce new species: - Trapping the Sun's energy and providing food for consumers - Providing shelter for other organisms - Changing the soil structure and recycling nutrients - Providing a food source of other organisms Decomposer's role: decomposers (fungi and bacteria) consume wastes and dead organisms returning their energy to the soil. Decomposers break energy down into simpler substances to get absorbed into the soil or consumed by organisms. Classification: Cytochrome c: a protein for aerobic respiration in essentially all living organisms, the proteins degree of similarity in amino acid sequence = close evolutionary relationship. Artificial classification: grouping of individuals based on observable traits. natural classification: grouping organisms based on morphological and anatomical characteristics. Must be passed down from a common ancestor e.g. predoctoral limb. Phylogenetic classification: grouping organisms based on similarity of DNA, organisms with similar genotypes are more closing related. Assessed by looking at amino acid and sequences of proteins. Taxonomy, domain, kingdom, phylum, class, order, family, genus, species Reproductive isolation Pre-zygotic mechanisms -- before fetilisation - Different mating calls, will not mate if not attracted to them hence mating rituals, ineffective for different species. - Different seasons/ time for mating - Specific chemicals to attract a mate - Different flower shape/ genitalia , anatomical differences make gamete transfer impossible. - Inability of sperm to survive in reproductive systems (pH) zygote will not form if egg and sperm do not fuse properly. Post- zygotic mechanisms: - after fertilisation - Zygote fail to develop - young fail to reach sexual maturity. - Offspring are infertile due to imbalance of parent's chromosomes making meiosis not occur. Carbon cycle: primary producers (during nighttime when the process of photosynthesis is not transpiring), and decomposers (bacteria, fungi,.) in a process that directly breaks down and releases co2. Consumers release co2 in respiration.