<< Chapter < Page Chapter >> Page >

The flowers and fruit borne by some trees are a source of food for many creatures.

The resin emitted by some trees is also important for certain animals.

When leaves or fruit fall from the trees and collect at the feet of the trees, another series of organisms can appear. The decomposers , such as micro-organisms that cause the dead material to decay and decompose, contribute to the decomposition of the nutrients so that they may return to the soil. Humus is formed in this way. Humus is dead organic material. Other creatures that live off decayed organic material, namely the detrivores , also promote this process of decomposition.

  • Poster to illustrate the Role-players in a Tree Ecosystem
  • Bring pictures of animals, trees and other plants to class. The teacher will divide the class into groups.
  • Each group will prepare a poster to illustrate the mutual dependence of the trees, other plants and animals. Each group must present its poster to the rest of the class.
  • Answer the following questions / follow the instructions arising from the class discussion:


1. Supposing the tree on your poster were to fall over.

1.1 Which organisms would die?

1.2 Which organisms would move away?

1.3 Which organisms would increase in number?

2. Describe the role played by trees in an ecosystem.

3. Ecologically speaking, why is it bad practice to rake up leaves under trees?

4. Name three more examples where humans harm ecosystems.

Assessment of POSTER and interpretation of related questions:

Were you able to use the joint information in order to answer the questions?

[LO 1.2; LO1.3]


To discuss rock pool ecosystems

[lo 2.1; lo2.2; lo2.3]

This ecosystem is extremely sensitive. The main factor that plays a role here, is TIDES.

The tide changes twice every 24 hours. As a result of the wave action, cold, oxygen-rich sea water washes over the rock pool communities. During low tide the water in the rock pools heats up and evaporation takes place. These changes contribute to the adaptation of the organisms that live in the rock pools so that they may survive the various challenges of nature.

1. Describe what you understand by “a rock pool”.

2. List all the abiotic factors that have an impact on rock pools.

Plants in rock pools

The most common plants are sea-weeds or sea-algae. They are red, green or brown.

Although they are not always green, they can also produce nutrients through photosynthesis. Therefore they are also producers.

They also provide nutrition for a wide range of other organisms that live off them, such as mussels and some sea-snails.

1. Do research in order to describe what each of the following is:

(a) filter feeders:

(b) scavengers:

2. What would the purpose of tentacles be in sea-anemones?

3. What kind of mutual dependence exists between the organisms in a rock pool?

Assessment of the interpretation of the SKETCHES

Could you distinguish the basic rock pool components?

[LO 2.1; LO 2.2; LO 2.3]


LO 1: Scientific investigations:

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

This is evident when the learner:

  • plans investigations;
  • conducts investigations and collects data;
  • evaluates data and communicates findings.

LO 2: Constructing Science Knowledge:

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

This is evident when the learner:

  • recalls meaningful information;
  • categorises information;
  • interprets information;

2.4 applies knowledge.


Activity: Discussing the value of a grassland ecosystem

  • Hard seedpods that cover seeds crack open
  • Air pollution – smoke
  • Species are rediscovered, e.g., the mountain rose
  • Animals and plants are injured and damaged, or killed
  • Plants that grow aggressively are restricted
  • Organisms in the soil are destroyed – humus is reduced
  • Younger plants provide better nutrition (green grass after a severe winter)
  • Grasses are weakened if burning is practised or occurs at the wrong time

Activity: Discussing a forest / tree ecosystem


1. Suppose the tree depicted in your poster were to topple over;

a. Plants that grow in the shade and have no resistance against direct sunlight.

b. Some creatures like birds and squirrels.

c. Decomposers like bacteria and fungi.

2. Accept the answers offered by learners, but ensure that the following are listed: habitat, shelter, source of food, shade.

3. Decomposition and the formation of humus are retarded: raw materials are not returned to the soil and the soil is impoverished.

4. Overgrazing, introduction of exotic plants, pollution.

Activity: Discussing a rock pool ecosystems

1. Accept the descriptions offered by learners. The following must form part of the information provided: saltwater, shallow water, high tide and low tide, extreme variations in a biotic conditions.

2. Wave action, wind, drying out, solar heating, pollution by people.


1. Research:

(a) Feeders that use filtering: mussels: minute food particles are filtered out of the water that flows through delicate structures.

(b) Carrion eaters: eaters of dead animals, e.g. crabs.

2. Tentacles: These grab bits of food from all directions and stuff it into the mouth in the absence of the senses of sight and smell.

3. Food-related aspects as touched on in earlier questions.

4. Shelter: plants provide shelter against predators.

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Natural sciences grade 8. OpenStax CNX. Sep 12, 2009 Download for free at http://cnx.org/content/col11050/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Natural sciences grade 8' conversation and receive update notifications?