Nutrients Flashcards
Food chain and levels
food chain is the circular system of nutrients acquisition of organisms
primary, secondary, tertiary and quaternary trophic levels
each organisms occupies a specific level based on their place in the food chain
autotrophs
those who make their own food/photosynthesis
chemoautotrophs- transform energy from chemicals. Occurs in places with high conc. of specific inorganic compounds (H, S)
photoautotrophs- transform light energy
plants and some bacteria
heterotrophs
those who cannot produce their own food
therefore they must get energy from autotrophs
herbivores but also carnivores and omnivores
detritivores
also known as decomposers. They consume already dead organisms, and can exist on any trophic level and play a critical role in recycling in the ecosystem
chemosynthesis in depth
occurs in ecosystems that lack sunlight and have high conc. of inorganic compounds such as H or S
can be symbionts with heterotrophs
There are many different pathways
Below is a pathway that bacteria and archaea use in hydrothermal vents
H2S and CO2 and O2 –> glucose, water and S
major pathways include: Calvin benson cycle, and reductive carboxylic acid cycle
What are the nutrients that plants need
17 overall
C, H, O, P, N, K, Ca, Mg, S, Cl, Fe, Mn, Bo, Cu, Mo, Zn, Ni
some are required in large quantities, and others in smaller amounts
How to plants get nutrients, what are their issues?
- Some nutrients must be taken up through the soil
- Plants often require the assistance of other organisms to take up these soil-bound nutrients
- Plants can generally reuse waste compounds or metabolic by-products, however, imbalances do occur, especially with regard to excess water
- Plants have developed a number of ways to ensure they do not retain excess water in their tissues
Nitrogen fixation
○ Soil-dwelling bacteria convert atmospheric nitrogen (triple bonded and hard for plants to break up), into ammonia (NH3), which is then converted into ammonium (NH4) or nitrate (NO3), which can be taken up by the plant
○ Requires large amounts of ATP which bacteria get from plant-derived carbs
○ Nitrification (2 step process that converts N2 into ammonia)
○ Provides plants with a form of nitrogen that they can use to synthesis proteins and nucleic acids
N fixation in Legumes
○ In legumes, nitrogen fixation occurs at nodules
○ This includes rhizobacteria
§ They do nitrogen fixation
§ Also protect by producing antibacterial agents
§ And through other ways
Fungal Mycorrhizae and other fungi
○ Important to plant nutrition, function in water acquisition, growth factor signalling and plant protection
○ Can help collect phosphate, copper and zinc
○ Produce antibiotics and protect against other pathogens
- Ectomycorrhizae ○ Covers roots and helps absorb water and minerals - Arbuscular mycorrhizae ○ Embedded within root tissue, increasing contact between the plant cells and the branching filaments of fungus, called hyphae
How do plants mainly excrete (2 main categories)
- These metabolic processes often produce by-products that are toxic to the organism and therefore need to be removed
- Control of excess water and gasses occurs primarily in the leaves and roots
Transpiration
- Transpiration controls water homeostasis, and facilitates the diffusion of excess oxygen out of the plants via the stomata
- Evaporation of water vapour from open stomata generates pressure in the leaves which draws water up the plant’s stem via the xylem and facilitates the absorption of water via the roots
- This is dynamic and reversible and responsive to a number of environmental and intrinsic signals
- Some plants permanently open pores on the stem
- Lenticels provide another avenue for unwanted water and gasses to exit
Urea
- Plants therefore generate urea (nitrogenous waste product) that needs to be removed
- Often converted and reused for protein synthesis
- Plants can store unwanted metabolic by products in vacuoles
- The waste then builds up in time in the tissues, which are then discarded as the tissue ages (e.g. fruit, leaves and bark)
Guttation
- During the day, stomata can open and close, however, in the night excess water accumulates as the stomata’s are closed and the roots still absorb water due to root pressure
- Therefore some plants undergo guttation in order to excrete this excess water
- Water can also be eliminated through guttation
○ Exudation of xylem sap in the form of water droplets through structures called hydathodes - It occurs when root pressure exceeds transpiration and forces the xylem sap through the secretory cells in the leaf epidermic called hydathodes
How do fungi feed?
- Fungi feed by growing into their food source.
- Fungal cells exude digestive enzymes into the surrounding substrate or tissue which breakdown large macromolecules that are then absorbed across the cell wall.
