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Key concepts

In this session we will focus on summarising what you need to know about:

  • Concept of an ecosystem
  • Structure and ecosystem function related to abiotic factors and biotic factors
  • Factors that influence terrestrial and aquatic primary production


Ecosystem - a community plus the physical environment that it occupies at a given time

Abiotic factors – non-living factors . Eg soil, air.

Biotic factors – living factors. Eg trees, insects.

Producer – organism that manufactures food by photosynthesis.

Herbivore – an organism that feeds on plants only.

Carnivore – an organism that feeds on animals only.

Omnivore – an organism that feeds on both plants and animals.

Saprotroph – an organism that feeds on dead and decaying matter. (fungi)

Decomposers – an organism that causes the decay of dead and dying organisms. (bacteria)

Scavenger – an organism that feeds on remains of animals.

Predator – an animal that hunts for its food.

Prey – an animal that is hunted and is food for the predator.

Food chain – a chain showing feeding relationships between organisms.


An ecosystem is a community of living organisms interacting with each other and their environment. Ecosystems occur in all sizes. A tidal pool, a pond, ariver, and a yellowwood forest are all examples of ecosystems. The living organisms (plants and animals) are referred to as biotic factors.The non-livingcomponents make up the abiotic factors. Organisms living in a particular ecosystem are adapted to the prevailing abiotic and biotic conditions.

Abiotic components

Abiotic factors may be grouped together as:

  • Physical / Climatic factors: sunlight, water, temperature and gases.
  • Edaphic factors: soil type, soil pH.
  • Physiographic factors: slope, aspect and altitude and latitude.

Climatic factors:


  • Light is a fundamental necessity.
  • The amount of sunlight an ecosystem receives is called insolation. This is critical for plant survival, especially in aquatic ecosystems. Light decreasesand water depth increases.
  • Amount of light changes from season to season.
  • In summer – days are longer, ecosystems gets more hours of sunlight than during short winter days.
  • The amount of sunlight affects other features of the ecosystem such as temperature, and the types of plants and animals that are found there.


  • Temperature increases with an increase in both latitude and altitude.
  • Temperature affects the rate at which photosynthesis, respiration and decomposition take place. The higher the temperature, the faster the processes.


  • Water is one of the most important factors in the ecosystem.
  • It is the main component of living cells and is essential for all living organisms.
  • About 80% of the human body and 90% of the plant body consists of water.
  • Water is evenly distributed over the earth.
  • It is abundant in aquatic ecosystems and least in deserts
  • Plants are adapted to the available amount of water in the following ways:
    • Xerophytes are plants that are able to live in dry habitats, or in regions with low annual rainfall. These plants are resistant to drought, have to cope withshortage of water, high temperatures and light intensities and dry warm winds. ie Cactus, Aloe
    • Hydrophytes are plants that are able to live entirely or partially in submerged water ot in very wet soil. These plants have to cope with a water surplus. ieWater lily, Water hyacinth
    • Mesophytes are plants that need an average, regular supply of water. ie Fruit trees, wheat

Questions & Answers

how do we prove the quadratic formular
Seidu Reply
hello, if you have a question about Algebra 2. I may be able to help. I am an Algebra 2 Teacher
Shirley Reply
thank you help me with how to prove the quadratic equation
may God blessed u for that. Please I want u to help me in sets.
what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
what is the coefficient of -4×
Mehri Reply
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
I'm 13 and I understand it great
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
hi vedant can u help me with some assignments
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
why and for what was five kingdom of classification of organisms introduced
give the ans as fast as possible
Comment on the ozone depletion over the period of 1982 to 1996
Mpho Reply

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Source:  OpenStax, Siyavula: life sciences grade 10. OpenStax CNX. Apr 11, 2012 Download for free at http://cnx.org/content/col11410/1.3
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