IB biology B4.2 ecological niches

define ecology

the study of the relationships between living organisms and their physical environment

define ecological niche

the role of a species in an ecosystem

what are biotic factors

the living parts of an ecosystem

what are abiotic factors

the non-living parts of the ecosystem

the interaction between biotic and abiotic factors influences the

growth, survival, reproduction, and how an organism obtains food

what obligate anaerobes

microorganisms that only respire when there is no oxygen and instead they use other compounds as electron accepters such as mercury. Oxygen is toxic to them because they do not have the right enzymes to deal with it

what are obligate aerobes

they require oxygen as a final electron acceptor to carry out respiration and release energy

how can you test for the kind of respiration used by a microorganism

place them in a culture containing thioglycolate, which has a low amount of sugar and removes oxygen. the top is exposed to air, but the bottom is devoid of oxygen, so obligate aerobes will migrate to the top, obligate anaerobes will migrate to the bottom, and facultative anaerobes will be in the middle

what are facultative anaerobes

capable of carrying out both aerobic and anaerobic respiration without being hurt or killed in the presence of oxygen

what are autotrophs

organisms that can generate their own source of nutrition usually from the sun through photosynthesis like plants, algae and some prokaryotes

what are heterotrophs

organisms that need to take in their nutrition from external sources like most anmals

what are mixotrophs

organisms that have evolved a combination of ways to gain energy

what do photosynthetic prokaryotes lack

membrane bound chloroplasts, and instead they have infoldings on their plasma membrane where photosynthesis takes place

what is holozoic nutrition

it refers to organisms that take in solid or liquid food internally. after it is brought inside, it is digested and broken down into smaller organic compounds that act as building blocks

what are examples of mixotrophic nutrition

euglena- facultative mixotroph

and some oceanic plankton

what are the two types of mixotrophs

obligate mixotrophs

facultative mixotrophs

what are obligate mixotrophs

they must use both autotrophic and heterotrophic modes of nutrition

what are facultative mixotrophs

they can use either heterotrophic or autotrophic modes of nutrition, switching between the two

what is saprotrophic nutrition

it is a method in which the organism secretes digestive enzymes that break down dead organic material into simpler molecules which are absorbed by the organism

what is a type of saprotrophic nutrition

decomposers, which obtain nutrients from dead organic matter like fungi and bacteria

what are the two types of heterotrophic nutrition

holozoic and saprotrophic

what are the two types of autotrophic nutrients

photoautotrophs

chemoautotrophs

what are detritivores

they break down dead organic matter by direct consumption

what are the three main domains

bacteria

eukarya with archea branching from it

what makes archea special

they have evolved enzymes which allow them to survive in extreme conditions such as high salt concentrations, very low pH, etc.

which energy source do archeas use

some use oxidation of inorganic chemicals such as sulfur (chemoautotrophs)

some use light (photoautotrophs)

some use energy from organic compounds (heterotrophs)

there is a relationship between —— and ——-

dentition and diet

hominins vs hominids

hominins are all modern and extinct humans and their immediate ancestors.

hominids include hominins and include the great apes

describe the dentition of Paranthropus robustus

large teeth with thick enamel

large chewing muscles and a wide face (strong jaw muscles)\

could grind tough fibrous foods and are believed to be herbivores that ate tough grasses

describe the dentition of homo floreniesis

they were short and had small brains but large teeth comparatively

it is believed they were omnivores and ate plants and uncooked meat because of the markings on their teeth which show they ate fibrous stuff that needed a lot of chewing

describe the dentition of homo sapiens

they evolved in africa and gathered food and hunted. they were adaptable and their jaws are less heavily developed and their teeth are smaller

Hominidae family includes

humans-homo, orangutans-pongo, gorillas-gorilla, and chimpanzees-pan

what are the teeth of herbivores

large and flat to grind down the plant tissues

large incisors with wide premolars

molars with rounded peaks and valleys

what are the teeth of omnivores

a mix of different types to break down both meat and plant

what are the teeth of carnivores

incisors and canines that are sharp and pointed

premolars and molars that are serrated and narrow

what is a molar used for

grinding and reducing food into a paste

what is a premolar used for

crushing or slicing up food

what are canines used for

ripping and tearing materials such as meat

what are incisors used for

cutting up bite sized pieces of food

look at this

look at this

what are some adaptations of insect herbivores

some insects have mandibles to cut and tear and chew their food

some insects feed off fluids internal using a stylet

what are some adaptations of herbivorous mammals (4)

they have long and flat incisors that can cut the plant material and back molars that can soften plant tissues by grinding them to increase the surface area for digestive enzymes to break the food down.

because they are always grinding, they can wear their teeth down and so they have constant teeth growth

they also have space between the premolars and incisors called diastema

giraffes have long necks and tough tongues to reach trees and protect themselves from thorns

how do herbivores protect themselves from being eaten

their eyes are on opposite sides of their head so they can increase their visual field

how do plants prevent herbivory (2)

they secrete toxic secondary compounds which are toxic to those that eat them but dont affect the plants

evolved non-toxic chemicals that only become toxic when ingested

how did animals respond to the selective pressures that were set by plants that did not want to be eaten for some reason

they developed special enzymes that enable them to metabolize those compounds and not be affected by them

they can also use them to protect themselves from predators sometimes

what are the plant compounds made for protection called and what are the 4 groups

phytochemicals

the four groups are:

terpenes

phenolics

polyketides

alkaloids

what is the benefit of phytochemicals other than for plants and give an example

they helped in the derivation of some medicine

artemisinin is a drug that has been used against malaria

paclitaxel is a chemical used for cancer

both came from trepene group

what are some physical adaptations of plants that help them avoid herbivory

having thick rigid leaves that are hard to chew

spiny thorns or microscopic thorns called trichomes

microscopic thorns have chemicals that can cause irritation

they sometimes hide by growing small

what are some physical adaptations of predators to help them kill prey

they have strong speed and agility and sharp claws and teeth

their digestive system can break down the prey

they have strong sensory systems that are finely tuned like the eagle

what are some chemical adaptations of predator to kill their prey

some release venom that paralyzes or poisons their victim by interfering with normal biological processes like the Brazilian fire ant and the cone snail

what are some behavioral adaptations of predators to catch their prey

ambushing the prey where they wait for them to come and then eat them like spiders

hunting in a pack like wolves

luring them like the margay and anglerfish

trapping them like dolphins

what are some physical adaptations of prey to resist predation

they use camouflage to blend into the background

they have some defensive mechanisms like porcupines

what are some chemical adaptations that help prey avoid predation

they sometimes release chemicals that are toxic into the air or water like skunks

what are some behavioral adaptations that help prey resist predation

they work together to deter the predator and look larger, like the mackerel

what are some adaptations of plants to harvest more light

some are epiphytes and grow on other plants

some are shade tolerant and have larger thinner leaves for maximum sunlight

some herbs grow on the bottom of the forest floor and can withstand low light conditions

lianas are climbing plants and grow on the plant away from light

some trees are really tall and can reach the canopy

what are epiphytes and what is one type of epiphyte and example for both

epiphytes grow on entirely separate plants

strangler epicpytes that climb on trees and shade them out, leading to the tree dying