Biology - Chapter 19 - Organisms and their environment

what is the principal source of energy input to biological systems

The sun

Flow of energy through living organisms

• light energy from the sun and chemical energy in organisms

• energy is eventually transferred to the environment e.g as heat

Define food chain

shows the transfer of energy from one organism to the next starting with a producer

define food web

a net work of interconnected food chains and interpret food webs

define producer

an organism that makes its organic nutrients, usually using energy from through photosynthesis

define consumer

an organism that gets its energy by feeding on other organisms

what can consumers be classed as

primary, secondary, tertiary and quatemary

example of a simple food chain

grass→mouse→owl

carrot→rabbit→fox→lion

grass→grasshopper→frog→snake→eagle

define herbivore

an animal that gets energy by eating plants

define carnivore

an animal that gets its energy from eating other animals

define primary consumers

herbivores -they feed on producer

define secondary consumers

predators that feed on primary consumers

define tertiary consumers

predators that feed on secondary consumers

define decomposers

bacteria and fungi that get their energy from feeding off dead and decaying organisms and undigested waste (such as faeces) by secreting enzymes to break them down

how population of animals is caused

by humans overharvesting and introducing foreign species to a habitat

define pyramid of number

diagram that shows how many organisms are there at each level of food chain (the larger an organism the less there are)

example of pyramid of number

define pyramid of biomass

shows how much mass creatures at level have without including water in body

example of pyramid of biomass

define pyramid of energy

represents energy found in trophic levels

example of pyramid of energy

90% of the energy lost goes up food chain as heat and in digested materials

define trophic level

position of an organism in a food chain, food web or ecological pyramid

advantages of using a pyramid of biomass rather than a pyramid of number to represent a food chain

it is more accurate because it quantifies the actual living matter at each trophic level

advantages of using a pyramid of energy rather than pyramids of numbers or biomass to represent a food chain

Energy pyramids show actual energy flow, account for inefficiencies, standardize units, reflect trophic structure, and highlight the importance of producers.

how a food chain goes

producer→primary→secondary→tertiary→quaternary

why the transfer of energy from one trophic level to another is often not efficient

energy is lost as heat and 10% of productivity of one level ends up as net productivity at next level

why food chains usually have fewer than five trophic levels

energy loss at each trophic level reduces available energy, limiting transfer efficiency and supporting fewer trophic levels

why is it more energy efficient for humans to eat crop plants than eat livestock that have been fed crop plant

energy is lost as it moves up the food chain

describe the carbon cycle

• photosynthesis - used

• respiration - released

• feeding - eaten

• decomposition - broken down

• formation of fossil fuels - stored

• combustion - released

describe nitrogen cycle

• decomposition of plant and animal protein to ammonium ions

• nitrification

• nitrogen fixation by lighting and bacteria

• absorption of nitrate ions by plants

• production of amino acids and proteins

• feeding and digestion of proteins

• deamination

• denitrification

roles of microorganisms in the nitrogen cycle

• decomposition - decomposes nitrogen compounds found in dead organisms into ammonium which releases nitrogen into soil

• nitrification - convert ammonium into nitrite and then nitrate so plants can readily absorb them

• nitrogen fixation - convert atmospheric nitrogen into forms of nitrogen that plants can use for growth

• denitrification - converts nitrate or nitrite back into gaseous nitrogen which returns unto atmosphere

define population

a group of organisms of one species, living in the same area , at the same time

define community

all of the populations of different species in an ecosystem

define ecosystem

a unit containing the community of organisms and their environemtn, interacting together

factors affecting rate of population growth for a population of an organism

• food supply

• competition

• predation

• disease

describe The Population Growth Curve

describe lag phase

organisms adapting to environment before they are able to reproduce

describe log phase

food supply is abundant, birth rate is rapid and death rate is low, growth is exponential they are adapted to environment, space is a lot

describe stationary phase

population levels out due to a factor in environment being limited. The birth rate and death rate is equal. space is limited

describe death phase

population decreases as death rate is now greater than birth rate because food supply is short