Ecology

Question 1

what is nitrogen cycle?

Answer 1

biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere , terrestrial and marine ecosystems

Question 2

describe the 5 steps in the nitrogen cycle

Answer 2

1. **Nitrogen fixation : convert nitrogen gas to ammonia. -Carried out by certain bacteria
   - occurs in roots of certain plants ( symbiotic relationships)
2. Nitrification: (ammonia to nitrate)
   - carried out by certain bacteria and archaeans
3. Assimilation: nitrogen into proteins and dna
4. Ammonification: bacteria or fungi convert organic nitrogen within remains of dead organisms back to ammonium.
5. Dentrification : conversion of nitrate to nitrogen gas: returns N2 to the atmosphere.

Question 3

Phosphorus cycle

Answer 3

• found in nucleic acids, phospholipids & ATP
• erodes from rock as PO4➡️ absorbed by plant roots
• animals get them from their diets
• decomposers release PO4 into the environment.

Question 4

water cycle

Answer 4

-Exchange of water between land, water, organisms
- continually renews the supply of water essential to life
-precipitation: into land and water bodies
- evaporation: from land and water bodies
Transpiration: from plants

Question 5

chemical elements of the ecosystem are passed —-1—- between—-2—- components through ——3—— cycles

Answer 5

1) back ad forth
2) abiotic and biotic
3) bio geochemical

Question 6

7 characteristics of fungi

Answer 6

1) eukaryotes
2) heterotrophic : most are decomposers, absorb nutrients
3) haploid cells
4)Chitin in cell walls
5)Most are multicellular
6) non motile but parts of them can move
7) both sexual and asexual reproduction

Question 7

difference between yeast and mold

Answer 7

yeast = round, unicellular , reproduce asexually ( by budding) but sometimes sexual by release of 1n spores from 2n sporangia
Molds= multicellular

Question 8

what is a hyphae

Answer 8

-forms when a fungal spore (single cell) land on a suitable spot, germinates then undergoes mitosis to form a multicellular hypha
- mitosis of haploid cells
- cell walls contain chitin
- is eukaryotic so has organelles

Question 9

hyphae can branch to form:

Answer 9

-Mycelium (to obtain nutrients)
-sporangia or fruiting bodies (reproduction)

Question 10

What is a fungal spore?

Answer 10

-single celled (microscopic) reproductive structure that is dispersed into the environment and can grow into a hyphae
- both asexual and sexual reproduction results in the production of spores

Question 11

Molds release spores (1n) from:

Answer 11

1) sporangia ( structure where spores are made)
2)Fruiting bodies

Question 12

Asexual reproduction in mold:

Answer 12

Spores released from sporangia, formed at the tips of the reproductive hyphae

Question 13

Sexual reproduction: spores( genetic diversity)

Answer 13

• spores produced sexually are different from those released in sporangia
  -produces distinct 1n spores that are released from fruiting body

Question 14

Spore dispersal (from sporangia and fruiting bodies)

Answer 14

• air currents
• water
• animals

Question 15

Ecological role of fungus

Answer 15

• most fungi are decomposers
• symbiotic relationships: ( mutualism, small fraction = parasites)

Question 16

Fungus vs bacteria as decomposers

Answer 16

Bacteria = grow and feed on exposed surfaces of organic matter
Fungus: can use hyphae to penetrate larger pieces of organic matter (on surface or within matter)

Question 17

Examples of symbiosis involving fungi

Answer 17

1) Mycorrhizal fungus : mutualism (w/ plants)
2) lichens : mutualism (b/w a fungus + phototroph (algae or Cyanobacteria))
3) fungus-animal : mutualism ( help breakdown plant material in cows guts, etc)
4) Parasitic : fungus- plant (Reduce you or kill the plant)
5) parasitic.: fungus in humans (Ringworm and athlete’s foot)

Question 18

Economic roles of fungi

Answer 18

-mutualism, parasitism have economic impacts
- source of medicines (antibiotics
- male alcohol, release CO2 by fermentation