19. Organisms and their environment Flashcards
What is photosynthesis (carbon cycle)?
converts carbon dioxide into carbohydrates, removes carbon dioxide from the atmosphere
What is respiration (carbon cycle)?
chemical process inside cells that releases energy
What is feeding (carbon cycle)?
ingesting organic matter from other organisms
What is decomposition (carbon cycle)?
breakdown of dead organic matter into simple nutrients/molecules that can be recycled back into the ecosystem
What is fossilisation (carbon cycle)?
dad organic matter compressed under optimum conditions into fossil fuels after millions of years
What is combustion (carbon cycle)?
complete oxidation of organic matter such as fossil fuels and biomass
What is decomposition (nitrogen cycle)?
proteins to ammonium ions
What is nitrification?
ammonium ions to nitrate ions
What is denitrification?
nitrate ions to nitrogen gas
Which organisms carry out nitrification?
nitrifying bacteria
What is a necessary condition for denitrification?
no presence of oxygen
For _______ to occur, no oxygen must be present.
denitrification
What is nitrogen fixation?
nitrogen gas to nitrates
Which organisms carry out decomposition?
by bacteria and fungi (decomposers)
Which organisms carry out nitrogen fixing? Where are they located?
nitrogen fixing bacteria
found in root nodules of legume plants
Which organism absorbs nitrate ions?
plants
What substance do plants absorb?
nitrate ions
What process can also carry out nitrogen fixation?
lightning
How do nitrates from lightning reach the soil?
rainwater
Where are amino acids/proteins made?
plants
Plants are responsible for producing which substance which is part of the nitrogen cycle?
amino acids/proteins
How are proteins transferred from producers to herbivores?
feeding
What is feeding?
process in which proteins transfer from producer to herbivore by ingestion
What happens once a herbivore feeds on a plant?
it will gain protein from the plant, digest it into amino acids, then used to make proteins.
carnivores eat herbivores and process restarts.
Which organisms carry out denitrification?
denitrifying bacteria
Define ‘population’.
a group of organisms of the same species, living in the same area at the same time
Define ‘community’.
all of the populations of different species in an ecosystem
Define ‘ecosystem’.
community interacting with abiotic factors in the environment
What are 4 factors that affect the rate of population growth for a population of an organism?
food supply
competition
predation
disease
State, in order, the phases of population growth (sigmoid curve).
lag phase
log phase
stationary phase
death phase
What happens in the lag phase? Why is population growth very slow in this phase?
- although abiotic factors are optimum, there are too few individuals, making it hard to find compatible mates
What are some examples of abiotic factors being optimum?
low competition for resources
high food + water availability
low spreading of diseases
What happens in the log phase? Why is population growth exponential in this phase?
- there are enough individuals to mate
- optimum conditions for reproduction
- no limiting factors
What happens in the stationary phase? Why is population growth stationary in this phase?
the high number of individuals increases competition for resources and mates
diseases spread more quickly
this keeps population stable
In terms of birth, death, emigration and immigration, what is a declining population?
death and emigration > brith and immigration
In terms of birth, death, emigration and immigration, what is an increasing population?
birth and immigration > death and emigration
What 4 factors can be used to calculate population growth?
birth,
immigration,
death,
emigration
What is the ‘formula’ for population growth?
births - deaths + immigration - emigration
What happens in the death phase? Why is population growth declining in this phase?
- struggle for survival as resources become limiting (used up)
individuals die
What are some limiting factors in population growth? (not in syllabus, ignora Anna <3)
resources
food
water
mates/partners
space
shelter
what is the principal source of
energy input to biological systems
Sun
what does a food chain show
the transfer of
energy from one organism to the next, beginning
with a producer
what is a food web
a network of
interconnected food chains and interpret food
webs
what is a producer
organism that makes
its own organic nutrients, usually using energy
from sunlight, through photosynthesis
what is a consumer
organism that gets its
energy by feeding on other organisms
how can consumers me classified
as primary,
secondary, tertiary and quaternary according to
their position in a food chain
what is a herbivore
animal that gets its
energy by eating plants
what is a carniovre
animal that gets its
energy by eating other animals
what is a decomposer
organism that gets
its energy from dead or waste organic material
Organic forms of nitrogen
protein, amino acids, DNA, urea
Inorganic forms of nitrogen
chemical fertilisers (NH4NO3), Nitrate (NO3), Ammonium gas (NH4), gas (N2)
What are the stages of the nitrogen cycle?
- ingestion
- digestion
- assimilation
- deamination
- decomposition
- nitrification
- absorption
- denitrification
- nitrogen fixing
inorganic forms of carbon
carbon dioxide, methane, ethanol
organic forms of carbon
carbohydrates, hydrocarbons, proteins, fats
