B4.2 Ecological Niches Flashcards
Ecological Niche
An organisms role in a particular habitat
Obligate aerobes
Require a continuous supply of oxygen
Obligate anerobes
Inhibited or killed by oxygen
Facultative anaerobes
Use oxygen when available but do anerobic respiration when it is not
Autotrophs/Producers
Organisms that carry out photosynthesis and .˙. make their own food
What are the 3 groups of organisms capable of photosynthesis?
Plants, Eukaryotic algae, several groups of bacteria
Heterotrophs
Organisms that cannot make their own food. Must eat other animals or plants for nutrition.
Mixotrophs
Both autotrophs and heterotrophs.
Holozoic Nutrition
Animals that ingest food and digest it internally
Stages of Holozoic nutrition
- Ingestion (taking food into gut)
- Digestion (breaking lg food molecules into smaller bits)
- Absorption (Transport of food molecules out of intestinal tissues to the blood supply then other tissues)
- Assimilation (using digested food to make new macromolecules and incorporating these into tissues)
- Egestion (voiding undigested material form the end of the gut)
Obligate mixotrophs
Must carry out photosynthesis and digest other organisms
Facultative mitotrophs
Can survive as either auto or mixotrophs and use the other mode of nutrition to supplement their diet.
Saprotrophs/ Decomposers
Heterotrophs that obtain organic nutrients from dead organisms by external digestion
External digestion of saprotrophs
They secrete digestive enzymes onto the dead organism/s and then absorb the organic compounds.
Chemosynthesis
The generation of cellular energy from inorganic (non carbon) molecules without the need for sunlight
How do archaea obtain nutrients?
Photosynthesis, chemosynthesis or heterotrophic nutrition
Herbivore teeth
Large and flat for grinding plant material
Omnivores teeth
Have a mixture of teeth to break down both plants and meat
Which human teeth are for biting pieces of food?
Incisors and canines (in front of mouth)
Which human teeth are for tearing and grinding food?
Pre-molars
Which human teeth are for chewing and grinding food?
Molars
Mandible
Lower jaw
Mechanical defenses of plants
Spines, thorns, prickles, stings, divaricating growth (tangled branches), seeds in hard cases
Chemical defenses of plants
Cells with cell walls containing cellulose (require specialised enzymes (that many organisms don’t have) to be digested, cyanogenic glycosides (release hydrogen cyanide), cardiac glycosides (heart poisons), insect hormones (disrupt insect growth ), tannins (taste bitter)
How do animals get around chemical defenses of plants
They eat younger leaves which usually have lower levels of toxins, they may have enzymes to detoxify/resist the toxins.
Physical adaptations of predators
- Using sight, smell, echolocation or changes in electromagnetic fields to detect prey
- Moving with speed and precision
- having claws, beaks and teeth to catch and break prey into smaller pieces and an effective digestion system
- being able to make complex decisions around timing, energy expenditure and risk while predating
Chemical adaptations of predators
- Injecting chemicals into their prey
- Luring the prey with chemical compounds like pheromones
Ambush predators
Hide and wait for prey to near and then pounce on them
Pack hunters
A group of animals that hunts together. They have an established relationship of trust and they choose a leader of the pack.
Pursuit Predators
Out run their prey by being very fast
Persistent hunters
Use endurance to chase prey for hours until it drops from fatigue
Physical adaptations of prey
- being camouflaged
- Being brightly or unusually coloured
- making warning vocalizations to scare off predators and warn other prey
- growing a protective shell
Chemical adaptations of prey
Producing toxic or bitter tasting compounds
Behavioural adaptations of prey
- Fleeing from predators
- Hiding
- Forming groups to find safety in numbers
What strategies do lianas use to get light?
climb through other plants using them for support and therefore don’t need as much xylem material (wood) as free standing trees
What strategies do trees use to get light?
A dominant shoot grows rapidly upwards to reach the forest canopy, where the tree receives full light
What strategies do epiphytes use to get light?
don’t have roots on the forest floor but grow on the trunks and branches of trees
What strategies do strangler epiphytes use to get light?
Grow by winding around tree trunks and can grow above the trees , shading them and eventually causing the tree to die due to it not getting enough light
What strategies do shade-tolerant shrubs and herbs use to get light?
can grow successfully on the forest floor in limited light levels
Fundamental niche
The niche it could have in an ecosystem if all the abiotic and biotic factors are within its range of tolerance
Realized niche
The niche a species can actually have in an ecosystem. Different form fundamental as It is in competition with other organisms for resources.
Competitive exclusion
“two species competing for the same limited resources cannot sustainably coexist or maintain constant population values”
