Energy Transfers in and between Organisms Flashcards
what is an ecosystem?
an ecosystem includes all the organisms living in a particular area and all the non-living conditions.
what is biomass?
biological molecules from glucose, as the product of photosynthesis, make up the plants biomass which is the mass of the living material
how can biomass be measured?
biomass can be measured in terms of the mass of carbon that an organism contains or the dry mass of its tissue per unit area.
what is dry mass?
dry mass is the mass of the organism with the water removed.
how is dry mass measured?
a sample of the organism is dried, often in an oven set to a low temperature.
the sample is then weighed at regular time intervals. once the mass becomes constant you know that all the water has been removed.
the mass of carbon present is generally taken to be 50% of the dry mass.
how can we calculate the amount of chemical energy stored in biomass?
using a calorimeter.
a sample of dry biomass is burnt and the energy released is used to heat a known volume of water.
the change in temperature of the water is used to calculate the chemical energy of the dry biomass.
what is gross primary production (GPP)?
the total amount of chemical energy converted from light energy by plants, in a given area.
what is respiratory loss (R)?
where approximately 50% of the gross primary production is lost to the environment as heat when the plants respire.
what is net primary production (NPP)?
the remaining chemical energy once respiratory loss has taken place.
this is the energy available to the plant for growth and reproduction, stored in the plant’s biomass, as well as the energy available to organisms at the next stage in the food chain.
what is the formula for NPP?
NPP = GPP - R
what specific properties does ATP have that makes it a good energy source?
-ATP stores or releases only a small, manageable amount of energy at a time, so no energy is wasted as heat.
-it’s a small, soluble molecule so it can be easily transported around the cell.
-it’s easily broken down, so energy can be easily released instantaneously.
-it can be quickly remade.
-it can make other molecules more reactive by transferring one of its phosphate groups to them.
-ATP can’t pass out of the cell, so the cell always has an immediate supply of energy.
define metabolic pathways
a series of small reactions controlled by enzymes
define phosphorylation
adding phosphate to a molecule
define photophosphorylation
adding phosphate to a molecule using light
define photolysis
the splitting of a molecule using light (photo) energy
