B4.2 ECOLOGICAL NICHES

Outline the differences between organisms that are obligate anaerobes, facultative anaerobes, and obligate aerobes

1. All living things perform cellular respiration

2. Anaerobic cellular respiration occurs in the absence of oxygen, aerobic cell respiration occurs with oxygen

3. Some organisms can use both aerobic & anaerobic

OBLIGATE ANAEROBES:

1. Cannot tolerate oxygen → anaerobic respiration

2. Methanogenic bacteria from oxygen free environment (early earth, deep in soil)

3. Early bacteria were obligate anaerobes but cyanobacteria began producing oxygen through photosynthesis

FACULATIVE AEROBES:

1. Tolerates oxygen

2. Anaerobic & aerobic respiration

3. Bakers yeast, E.coli

OBLIGATE AEROBES:

1. Requires oxygen, aerobic respiration

2. May be able to carry anaerobic respiration for short periods of time

3. Animals, must fungi (not yeast), some bacteria

Outline photosynthesis as a mode

1. Photosynthesis is the mode of nutrition in plants, algae, and several groups of photosynthetic prokaryotes

2. Autotrophs synthesis their own organic compounds/foods from inorganic compounds

   1. Chemoautotrophs: synthesis their own organic compounds/food from inorganic compounds

   2. Photoautotrophs perform photosynthesis

Outline the differences between organisms that are obligate anaerobes, facultative anaerobes, and obligate aerobes

1. All living things perform cellular respiration

2. Anaerobic cellular respiration occurs in the absence of oxygen, aerobic cell respiration occurs with oxygen

3. Some organisms can use both aerobic & anaerobic

OBLIGATE ANAEROBES:

1. Cannot tolerate oxygen → anaerobic respiration

2. Methanogenic bacteria from oxygen free environment (early earth, deep in soil)

3. Early bacteria were obligate anaerobes but cyanobacteria began producing oxygen through photosynthesis

FACULATIVE AEROBES:

1. Tolerates oxygen

2. Anaerobic & aerobic respiration

3. Bakers yeast, E.coli

OBLIGATE AEROBES:

1. Requires oxygen, aerobic respiration

2. May be able to carry anaerobic respiration for short periods of time

3. Animals, must fungi (not yeast), some bacteria

Outline photosynthesis as a mode

1. Photosynthesis is the mode of nutrition in plants, algae, and several groups of photosynthetic prokaryotes

2. Autotrophs synthesis their own organic compounds/foods from inorganic compounds

   1. Chemoautotrophs: synthesis their own organic compounds/food from inorganic compounds

   2. Photoautotrophs perform photosynthesis

Outline the mode of nutrition for heterotrophs

1. HETEROTROPHS: Obtain matter from other living organisms

2. All animals are heterotrophic & consumers and have holozoic nutrition

3. Food is ingested, digested internally, absorbed and assimiliated

Outline mixotrophic nutrition

1. Some protists have mixotrophic nutrition: more than one type of nutrition can be used

2. Euglena is a freshwater protists that is both autotrophic and heterotrophic

3. Can either be obligate mixotrophs (requires both forms) or facultative mixotrophic

4. Coral is an animal polyp that gains organic molecules from symbiotic photosynthetic algae and from filter feeding

5. Marine plankton: dinoflagellates are photosynthetic and can feed on other organisms

6. Carnivorous plants: perform photosynthesis and obtain nutrients from digested insects

Outline saprotrophic nutrition

1. A type of heterotrophic nutrition

2. Saprotrophs secrete enzymes to digest externally and then absorb nutrients

3. Saprotrophic fungi and bacteria are decomposers

Outline the diversity of nutrition in archae

1. Archae are one of the three domains of life and are metabolically diverse. They use either:

2. Light: Halobacteria use H+ pumps to produce ATP (no oxygen released!)

3. Oxidation of inorganic chemicals/carbon compounds: chemoautotrophic uses this to provide energy for ATP production

Outline the relationship between dentition and diet

Fossil evidence can predict the diet of extinct species:

1. Homo floresiensis: Plant-based diet

   1. Square and robust jaw

   2. Large premolars and tooth abrasion

   3. Similar shape skull to humans suggests tool use & some meat eating behaviour

2. Paranthropus: Herbivorous diet

   1. Large skull/jaw for chewing vegetation

   2. Large molars for grinding

   3. Thick tooth enamel to protect from tough plant material

3. Homo sapiens: Omnivorous diet

   1. Molars and incisors are small

   2. Canines are short

   3. Smaller joy with larger cranium & v-shaped jaw

What are the factors that determines of dentition that suggest diet

Compare skulls to evaluate:

1. Jaw size/shape

2. Size of incisors

3. Size of canines

4. premolar/moalrs

Outline adaption of herbivores

HERBIVORES: Animals/insects that feet on plants

1. Aphids have stylets to pierce the stems and obtain sugars in the phloem

2. Chewing mouthparts of grasshoppers, locusts, cockroaches, beetles, caterpillars and termintes

Outline adaptions of plants to resist herbivory

PHSYICAL STRUCTURE:

1. Thorns to prevent herbivory

2. Cacti have sharp spines from eating succulent stems

3. Thick bark prevents insects (aphids) form piercing stems

4. Tiny Hairs on leaves make it difficult to pierce plant tissue

TOXIC SECONDARY COMPOUNDS (produced in seeds/leaves):

1. Nettles have hairs that produce toxins and irritate skin

2. Nightshade contains toxins in leaves, stems, berries & roots

3. Some animals like proboscis monkey in Borneo have metabolic adaptations, like intestinal bacteria to neutralise toxins

Outline adaptions for predators

CHEMICAL:

1. Venom to paralyse the prey: snakes, scorpions, spiders

2. Chemical mimicry to attract prey; bolas spiders mimic the scent of female moths

3. Scent camouflage to mask predator scent

PHYSICAL:

1. Eye location predators have eyes located at the front of their head for better depth perception/binocular vision

2. Specialised sense organs for detecting prey: Rattle snakes use tongue to detect chemicals emited by prey, bats use echolocation to detect prey movements

BEHAVIOURAL:

1. Pack predation hunts in groups/packs: killer whales, wolves, hyenas

2. Ambush predators have motionless body movements to surprise prey

3. Pursuit predators have burst of speed to capture prey

Outline adaptations in prey

CHEMICAL:

1. Toxins that deter predators: poison dark frogs produce toxins in the skin, skunks release chemical scents that deter predators

2. Scent chemicals to prevent detection

PHYSICAL:

1. Eye location prey have eys located on the size of the heat to view the surrounding area and detect predators

2. Camouflage to avoid detection

BEHAVIOURAL:

1. Speed for escape

2. Group together to protect the herd

3. Bluffing and paying dead, rolling up in a ball

Outline adaptions of plant form for harvesting light

1. Trees growth to greater heights allow them to access more light and perform more photosynthesis

   1. Emergent tress extend above the canopy & have greater access — higher rates of photosynthesis

   2. Understory tress grow below the canopy

2. Lianas are woody vines that use the trees for support to reach the canopy and gain access to light

   1. They germinate in the soil and compete with the trees for water and nutrients

3. Epiphytes: bird’s nest & bromeliads growing on branches to gain nutrients & water from the rainwate (not soil)

4. Stranger epiphytes: germinates in the branches and then grows down into the soil to access water and nutrients

5. Shade tolerant shrubs: woody stems plants with less access to light they have adapted by developing larger leaves & different pigments to increase light absorption and strong scented pollens to attract insects

6. Herbs: lack a woody stem have a low growth form