lecture 19 Flashcards
available forms of Hydrogen
H2O
available forms of Carbon
CO2
available forms of Oxygen
- O2, CO2, H2O
- carbohydrates and other organic compounds
available forms of Nitrogen
- NO3-, NH4+, N2
- amino acids (proteins), chlorophyll, nucleic acids
available forms of Phosphorous
- H2PO4-, HPO4^2-
- nucleic acids, energy transfer (ATP), phospholipids
available forms of Sulfur
- SO4^2-
- amino acids and proteins
available forms of Potassium
- K+
- osmoregulation, movement
available forms of Calcium
- Ca^2+
- root hair growth, cell division, signaling
available forms of Magnesium
- Mg^2+
- chlorophyll
which elements make up the structural components of a plant (~98% of the dry weight)?
hydrogen, carbon, oxygen, nitrogen, phosphorous, sulfur
which elements are involved in fundamental processes in the plant (~1.5% dry weight)?
potassium, calcium, magnesium
which elements are considered micronutrients?
Cl, B, Fe, Mn, Zn, Cu, Mo, Ni
what is the role of iron?
chlorophyll synthesis and respiration
what is the role of Boron?
component of plant cell walls
what is the role of manganese?
enzyme cofactor and photosynthesis
what is the role of nickel?
only known role is to activate urease, an enzyme involved in nitrogen metabolism
what are the two important factors in plant nutrient status?
availability in the soil and uptake into the plant
what factors influence the availability of nutrients in the soil?
- soil structure
- moisture
- temperature
- pH
how can soil pH be altered?
secreting H+ or organic acids to lower soil pH and increase nutrient uptake through cation exchange, co-transport (anions), and solubility
what methods have plants adapted to increase their ability to explore the soil and absorb nutrients?
- lateral roots and root hairs
- development of symbiotic associations with fungi called mycorhizzae (fungus-roots)
how is nitrogen absorbed in the plant?
- organic matter in the soil breaks down, releasing nitrogen into the soil as ammonia
- nitrifying bacteria convert soil ammonia to nitrate
what is biological nitrogen fixation?
process where free-living bacteria convert atmospheric nitrogen to ammonia
how do seeds store carbon?
as starch or as oil, which is broken down and used as an energy source in respiration
what are amyloplasts?
specialized plastids densely packed with starch; play a role in gravitropism
what is phytate?
a hexose sugar with a PO4 at each carbon; gives it a highly negative charge and associated with cations
