PACK 14: ECOSYSTEMS Flashcards
(23 cards)
define a community
all the organisms present in a habitat
define population
all the individuals of the same species in a habitat at a particular time that can interbreed
define ecosystem
consists of all of the living populations and non-living components of the environment
what is interspecific competition
competition within different species for food, light, minerals, etc.
e.g. a lion and an elephant
(remember international is different countries)
what is intraspecific competition
competition between the same species for food, light, minerals, but also mates (at breeding can only occur within the same species)
e.g. a tabby cat and a siamese cat
do changes in predator population size change before or after prey population size?
after
define carrying capacity
the maximum size that a population can remain sustainable in a particular habitat
what are autotrophs?
primary producers, e.g. green plants like algae
what are heterotrophs
they can be any of the primary, secondary, or tertiary consumers
what are saprobionts and what do they do?
they are typically bacteria or fungi that secrete enzymes onto detritus (waste/debris of any kind) this is extra cellular digestion, and then absorb the products of digestion
why is not all light energy that a plant absorbed used for photosynthesis?
it may not strike the chlorophyll so photolysis and photoionisation won’t occur, some of the light has an inappropriate wavelength to be used in photosynthesis, or sometimes the light is reflected or transmitted through the leaf
why is not all light energy converted into glucose?
energy may be lost due to inefficient reactions during photosynthesis, or limiting factors of photosynthesis like CO2 concentration, light intensity, and temperature
what is biomass?
the mass of organic material in an organism or an ecosystem
how to measure biomass of a plant in a large field
collect all of the desired plants in one square meter and dry the plants at 80 degrees, weigh them and dry them again until there is no mass change so you know the plants are completely dry and then multiply the final dry mass by the total number of square meters in the large field.
e.g. 10g of plant bio mass in one square meter of a 50 square meter field, so tikes 10 by 50 to get 500g of biomass in the field
how to calculate the energy store in dry biomass
using a calorimeter
how does a bomb calorimeter work
dry material is burnt in oxygen, the energy given off heats up water in the calorimeter. the rise in temperature can be used to calculate the energy (in calories) that was contained in the material
how to calculate NPP and what are the units
Net Primary Production = Gross Primary Production (GPP) - Respiratory Losses (RL)
the unit of energy per unit area or volume e.g. KJm2
define net primary production
the chemical energy store in plant biomass after respiratory losses
define gross primary production
the chemical energy store in plant biomass in a given area or volume
how to calculate the efficiency of energy transfer
energy transfer = (energy available after the transfer / energy available before the transfer) x 100
why is the energy transfer to consumers inefficient?
some food is not digested and is lost in feces
some is energy is lost due to excretion of metabolic waste products, e.g. urea
some parts of an organism are not eaten or inedible, e.g. roots or bones
lots of energy is lost as heat to the environment through respiration
how can farmers increase their production by increasing the efficiency of energy transfer?
reducing respiratory losses within a human food chain (utilising all parts of the plant in food e.g. potato skins)
simplifying food webs to reduce energy losses to non-human food chains e.g. using pesticides to prevent and reduce the amount of crops eaten by pests
describe the process of succession
a hostile environment is colonised by a pioneer species. the abiotic environment of the habitat is changed by the pioneer species, changing the environment to become more hospitable to a new species. the establishment of new plant species and groups of animals increases the species diversity. the early colonisers are replaced by new species. changes in abiotic factors result in a less hostile environment and leas to an increase in biodiversity- leaving to the development of a climax community.
