Biology Ecosystems and Survivorship Quiz

Community Interactions

• Organisms interact as individuals and populations.
• Competition and predation are important ways organisms interact.
• Competition occurs when two organisms fight for the same limited resource.
  • Intraspecific competition
  • Interspecific competition
• Predation occurs when one organism captures and eats another.
• There are three major symbiotic relationships:
  • Mutualism: both organisms benefit.
  • Commensalism: one organism benefits, the other is unharmed.
    • Example: Eyelash mites on eyelashes. The mites benefit and the eyelashes are not affected.
  • Parasitism: one organism benefits, the other is harmed.
    • Example: Braconid wasp larvae feed on the host hornworm, and the hornworm is killed.
    • Parasites can be ectoparasites (like leeches) or endoparasites (like hookworms).

Domains and Kingdoms

• The current tree of life has three domains: Bacteria, Archaea, Eukarya.
• Six kingdoms are included in the three domains. Six kingdoms: Bacteria, Archaea, Protists, Fungi, Plantae, Animalia.
• Organisms are classified into domains based on cell type and structure.
• Organisms are classified into kingdoms based on cell type, structure and nutrition.
• Prokaryotes lack a nucleus. Their DNA is not enclosed within a membrane-bound structure.
  • Bacteria: cell walls contain peptidoglycan. Most abundant organism on the planet. Classified by shape, need for oxygen, and diseases caused. Bacteria come in three shapes: rod (bacilli), spiral, and spherical (cocci).
  • Archaea: their cell walls do NOT contain peptidoglycan. They live in extreme environments, such as deep sea vents, hot geysers, Antarctic waters, and salt lakes.
• Eukaryotes have a nucleus.
  • Made up of all organisms with eukaryotic cells. Includes 6 kingdoms (Plantae, Animalia, Protista, Fungi). Some eukaryotes are single-celled (like protists), some are multicellular (like animals).

Pyramid Models

• Energy pyramids show the distribution of energy among trophic levels.
• Energy pyramids compare energy used by producers and other organisms.
• Between each tier, up to 90% of the energy is lost as heat to the atmosphere.
• Only 10% of the energy is transferred from one trophic level to the next.
• Other pyramid models illustrate biomass and distribution of organisms.
• Biomass is a measure of the total dry mass of organisms in a given area.
• A pyramid of numbers shows the number of individual organisms at each trophic level.
• A vast number of producers are required to support even a few top-level consumers.

Cycling of Matter

• Water cycles through the environment in a circular pathway.
• Organisms have bodies made mostly of water.
• Elements essential for life cycle through ecosystems.
• A biogeochemical cycle is the movement of a chemical through biological and geological parts of an ecosystem.
  • Oxygen cycles indirectly through an ecosystem by cycling other nutrients. (photosynthesis and respiration)
  • Carbon moves from the atmosphere, through the food web, and returns to the atmosphere. Some carbon remains stored in carbon sinks for long periods.
  • The nitrogen cycle mostly takes place underground. Some bacteria convert gaseous nitrogen into ammonia through nitrogen fixation. Nitrogen-fixing bacteria live in plant nodules or freely in the soil. Ammonia is released into the soil, transformed into ammonium, then into nitrate by nitrifying bacteria. Nitrogen moves through the food web and returns to the soil during decomposition.
  • The phosphorus cycle takes place at and below ground level. Phosphate is released into the environment by weathering of rocks. Phosphorus moves through the food web and returns to the soil during decomposition. Phosphorus leaches into groundwater, and is locked in sediments. Mining and agriculture add phosphorus to the environment.

Population and Growth Patterns

• Changes in a population's size are determined by immigration, births, emigration, and deaths.
• The size of a species' population is always changing.
• Four factors affecting population size: immigration, emigration, births, and deaths.
• Population growth is based on available resources.
• Exponential growth is a rapid population increase due to an abundance of resources.
• Logistic growth is due to limited resources; this type of growth eventually slows to a stop, reaching a carrying capacity.
• Carrying capacity is the maximum number of individuals in a population that the environment can support.
• A population crash is a dramatic decline in the size of a population over a short period.
• Ecological factors can limit population growth, including factors that are density-dependent (predation, competition, parasitism, and disease) and density-independent (unusual weather, natural disasters, and human activities).

Viruses

• Viruses have no structures to maintain—no membranes or organelles needing ATP, oxygen, or glucose.
• All it carries into the cell is what it needs to reproduce—its genes.
• Viruses, viroids, and prions can all cause infection.
• A virus is made of DNA or RNA and a protein coat.
  • A virus can infect many organisms.
  • A virus needs a living cell to reproduce and to make proteins.
• A viroid is made only of single-stranded RNA without a protein coat; it causes diseases in plants.
• A prion is composed of proteins with no genetic material. These proteins misfold other proteins, causing diseases of the brain.
• Viruses have a simple structure: genetic material, a capsid (protein shell) and sometimes a lipid envelope.
  • Bacteriophages; a group of viruses that infect bacteria.
  • Bacteriophages have a head (containing DNA), a tail sheath, and tail fibers to inject DNA into bacteria.
• Viruses infect eukaryotes with endocytosis: viruses enter eukaryotic cells by forming vesicles, or membrane-bound sacs, around the molecules or by fusing with the plasma membrane of the host cell. Some viruses, such as HIV, target the cell's nucleus.
• Viruses cause two types of infections: lytic (host cell bursts) and lysogenic (prophage reproduces with host DNA).
• Vaccines prepare the immune system for a future attack. A vaccine stimulates the body's own immune response to a virus.

Linnaean System of Classification

• Organisms can be classified based on similarities.
• Linnaeus developed the scientific naming system currently used.
  • Taxonomy is the science of naming and classifying organisms.
  • A taxon is a group of organisms.
  • Binomial nomenclature gives each species a scientific name with two parts: genus and species.
  • The genus name is always capitalized; the species descriptor is always lowercase.
  • Linnaean taxonomy classifies organism’s based on their physical and structural similarities.
• Organisms are placed into different levels in a hierarchy. Several distinct levels are nested in each one above it. From kingdom to species, levels progressively become more specific.
• The Linnaean system has limitations in that it does not account for molecular evidence. Physical similarities don't always reflect evolutionary relationships; genetic similarities more accurately show relationships.