REVISION: ECOLOGY 18 SEPTEMBER 2013
Lesson Description
In this lesson we:
Revise important concepts in ecology include practical investigations
Key Concepts
The Biosphere
The part of the planet that supports life e.g. atmosphere(air), lithosphere (land) and
hydrosphere(water
The Lithosphere
The lithosphere is the solid, rocky crust covering entire planet. This crust is inorganic and is
composed of minerals. It covers the entire surface of the earth.
This is where terrestrial organisms live
The shape of the land surface is called its topography.
A thin layer of soil supports life. Soil is formed from weathered rock
The soil provides plants with nutrients and water to support all the organisms in a food chain
The Atmosphere
The atmosphere is the body of air which surrounds our planet. Most of our atmosphere is
located close to the earth's surface where it is most dense. The air of our planet is 79%
nitrogen and just under 21% oxygen; the small amount remaining is composed of carbon
dioxide and other gasses.
The atmosphere consists of five layers of gases that support life and protect us from harmful
radiation from the sun
The Hydrosphere
The hydrosphere is composed of all of the water on or near the earth. This includes the
oceans, rivers, lakes, and even the moisture in the air. Ninety-seven percent of the earth's
water is in the oceans. The remaining three percent is fresh water; three-quarters of the fresh
water is solid and exists in ice sheets
Aquatic organisms depend on the hydrosphere for life
Interconnections of the Spheres
The lithosphere, hydrosphere and atmosphere form the biosphere.
The soil, water and air support life on earth.
Life on earth is linked in each of the three spheres.
All four spheres can be and often are present in a single location. For example, a piece of soil
will of course have mineral material from the lithosphere. Additionally, there will be elements
of the hydrosphere present as moisture within the soil, the biosphere as insects and plants,
and even the atmosphere as pockets of air between soil pieces.
There are two components to the biosphere
o A biotic or living component –
animals, plants microorganisms
etc.
o An abiotic or non-living
component – water air
temperature, soil etc.
o The biotic and abiotic factors of the
biosphere form the global
ecosystem
Living organisms are not evenly distributed
throughout the biosphere.
Scientists have divided the earth into
regions according to their climate, soil,
plants and animals that live their – these
regions are called biomes
Biomes are sub-divided into ecosystems.
Ecosystems are communities of
organisms that interact in a particular
environment.
An organism lives in a certain place where
it gets its food, space and where it
reproduces – this is called its habitat
Scientists divide biomes into :
o Terrestrial biomes that occur on land – grasslands, savannah, fynbos
o Aquatic biomes - marine, wetlands, coastal
South African Biomes – Terrestrial
BIOMES CHARACTERISTICS
1. Savannah
• Savannas are the wooded grasslands of the tropics and subtropics that account for 46% of the South African landscape.
• Stretches from the Kalahari in the west into the north and north-east of Limpopo
• Rainfall2oo-1000mm • Summers hot and wet • Winter cool and dry • Soil fertile • Vegetation: Grasses, thorn tress, large
shrubs, trees (marula, baobab) • Animals:‘Big 5” blue wildebeest, eland,
hippo, kudu, cheetah, zebra, giraffe, wild dogs
2. Grassland
• The grasslands cover the high central plateau of South Africa, inland areas of Kwazulu-Natal and the mountain areas of the Eastern Cape Province
• Variety – rainfall varies, thunderstorms and hailstorms
• Winters cold with or without frost, fires common
• Summer – hot and wet • Soil type- fertile • Plants - Grasses (rooigras) • Animals - Blesbok, black wildebeest,
springbok
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3. Nama-Karoo
• The Nama-Karoo covers most of the vast central plateau region of the Western and Northern Cape Provinces.
• Semi-desert – flat and rugged • Ground dry and rocky • No permanently flowing rivers (no rain) • Rainfall less than 500mm • Summer high temp • Winter freezing cold • Soil – rich in lime, thin layer of soil over
rock, infertile • Plants – xerophytes, low bushes, grass and
shrubs - Stone plant, sweet thorn, Karoo daisy
• Animals - black-eared jackal, leopard, baboon, vervet monkey, tawny eagle
4. Succulent Karoo
• This biome occurs mostly west of the western escarpment through the western belt of the Western Cape and inland towards the Little Karoo.
• The succulent Karoo is restricted to the year-round and winter rainfall areas and have the greatest summer aridity
• Rainfall - dry, 50mm-350mm rainfall • Summers – hot and dry • Soil – rich in lime, infertile and erodes easily • Plants – xerophytic, Namaqualand daisies,
succulents, lichens • Animals – small rodents- mice squirrels,
Bat- eared fox, suricate, barking gecko
5. Fynbos
• Fynbos occupies 5,3 % of South Africa, occurring almost exclusively in the south-western and southern parts of the Western Cape Province.
• Winters cold and wet – 210-3000mm • Summers hot and dry • Soil – infertile soil that is leached of all its
nutrients – inhibits growth of larger plants • 68% of plants endemic to the fynbos biome • One of the six floral kingdoms in the world • Fires common in summer – needed to
stimulate germination • Plants- Proteas, shrubs and trees, rooibos
tea, buchu, olives, table wine, thatching reed
• Animals - Klipspringer, Cape mountain zebra, leopard, geometric tortoise, baboons, porcupines, lynxes , Cape sugar bird
South African Biomes – Aquatic
Marine and Coastal Biomes Include – oceans, coral reefs and estuaries
Biomes include salty water.
Algae live in the water and produce oxygen and food
South African marine biome contains 12% of the worlds fish species. Our coastline is 3000km
long
Water on the east coast is warm because of the warm Indian current and the water on the
waest coast is cold because of the Benguela current.
The west coast water are rich in nutrients which provides food for plankton and fish
Organisms
Plankton- phytoplankton (algae), zooplankton (microscopic crustaceans) – fish and large fish
– sharks, dolphins, whales – animals living on the bottom – crabs, oysters, sponges, lobster
etc.
Organisms have to endure various abiotic factors:
o Saltiness
o Ocean currents and waves
o Oxygen variation
o Variations in sunlight
o Depth and temperature of water
o Concentration of nutrients
6. Forests
• Smallest biome. Mountainous forests along the Southern Cape coastline – Knysna and Tsitsikamma
• Rainfall – throughout year, mainly winter • Forests cool and moist, humid • Soil deep and fertile • Plants - Outeniqua Yellowwood, epiphytes,
herbaceous and bulbous plants • Animals - Blue duiker, bush-pig, Knysna
Lourie and woodpecker , paradise flycatcher
7. Thickets
• Along the coast of Kwa-Zulu Natal and Eastern Cape
• Rainfall fairly high but not sustainable for forests
• Soil – shallow and varies from sandy loam to sandy clay that is rich in lime
• Plants – varies, shrubland to low forests, evergreen and succulent trees and shrubs, plants have thorns. Short trees, spekboom, Cape honeysuckle, Plumbago
• Animals - Elephants, antelopes, monkeys, squirrels, bushbuck , African python
Coral Reefs Shallow waters off the northern coast of
Kwa-Zulu Natal
Coral reefs are formed from calcium
carbonate of tiny corral animals
Large biodiversity
Animals – micro-organisms, invertebrates,
fish, sea urchins, sea-stars, octopusi
Open Sea Zone Open ocean
Temperature is generally cold
Plankton main food provider for fish, dolphins and whales
Wetlands
Area of land which is covered predominately by shallow water.
Include mountain springs, marshlands, flood plains, estuaries to swamp forests that are linked
by river and streams.
Rich in biodiversity:
o Birds
o Large amount of carbon
o These wetlands share common and
important functions in river catchments
by providing a regular water supply, by
filtering the water naturally
o By reducing the effects of floods and
droughts.
Estuaries
Are areas where freshwater of streams or rivers
meet with the salt water of the sea
Water conditions, temperature and salt content,
change constantly with the tides
Rich in nutrients
Plants – algae, seaweed, marsh grass and
mangroves
Animal – prawns, sponges, mussels, barnacles,
crabs
Correct Format of a Scientific Report By using a scientific process we can ask questions, find answers and make decisions based on what
we have discovered in a scientific way. This scientific method helps us to THINK LOGICALLY.
All investigations and experiments that we do in Life Sciences should follow some basic steps. These
steps must be written down to record what we did and what we found.
Here is a summary of the headings and lay-out for a typical experiment
Aim: This gives the purpose of the experiment and is often stated as a question.
Hypothesis: Making an ‘educated guess’. Stating what you THINK will happen in the experiment.
Apparatus: This is a simple list of the pieces of apparatus used. A labelled diagram of the apparatus is sometimes necessary for understanding the experiment
Method: This section is written in full sentences, but using numbered points, NOT in a paragraph.
Results: This is where you record your observations and look at the data that you have collected. All results are recorded clearly in TABLE format with appropriate headings.
Interpretation of Results
This section includes GRAPHS drawn from the results, and may also consist
of some answered questions about the results which help to make sense of
the results.
Conclusion: This section must provide an ANSWER TO THE AIM, and must refer to the
results that you have obtained.
Important Terms
Biosphere Ecosystems Aquatic Lithosphere Biodiversity Terrestrial Atmosphere Biomes Estuary Hydrosphere Endemic Hypothesis Phototropism Universal indicator Independent variable Experiment Dependent variable Control
Questions
Question 1
Study the map below where South Africa’s terrestrial biomes are indicated with the letters A to G and
answer the questions that follow
a.) Define the term biome
b.) Identify the biomes A-F
c.) Which biome is a main tourist attraction during spring, when the whole area is covered with
flowers?
d.) Which biome includes one of the world’s richest floral kingdoms?
e.) Which biome attracts tourists to its many game farms?
f.) Which biome is the largest?
g.) Which biome will you find the following plant species?
i. Vygies, quiver trees
ii. Yellowwood and stinkwood
iii. Mopani and baobab
iv. Proteas, ericas and reeds
Question 2
In 1950 an American scientist, Thomas Park, investigated organisms that seemed to compete for the
same resource. He used two different species of beetle called Tribolium castaneum and Tribolium
confusum that both eat flour. These small beetles look similar and both live in and lay their eggs in
flour. Thomas Park carried out the investigation as follows:
He put the same amount of flour into each jar.
He put the same number of beetles of each species into each jar (see table below).
He kept the jars at different constant temperatures (see table below).
He let the beetles breed for several generations.
After the same period of time, he removed the beetles from the jars and counted them.
His results showed that the two different species preferred different conditions of temperature and
moisture as shown in the results below:
Tribolium beetle
Magnification 100x
Conditions Percent of
times only
Tribolium
castaneum was
left in the jar
Conditions Percent of times
only Tribolium
confusum was
left in the jar
Cold, dry 0 Cold, dry 100
Temperate, dry 13 Temperate, dry 87
Hot, dry 10 Hot, dry 91
Cold, moist 29 Cold, moist 71
Temperate moist 86 Temperate
moist 14
Hot, moist 100 Hot, moist 0
a.) Draw a suitable graph to represent the data above for Tribolium castaneum ONLY. Use the
graph paper provided on your answer sheet. (10)
b.) Which two variables did Thomas Park change to see their effect? (2) c.) Which species of beetle succeeded best in dry conditions? (1) d.) Which species of beetle succeeded best in moist conditions? (1) e.) Which species of beetle could survive hot temperatures and high humidity the best? (1)
f.) Give a hypothesis for this experiment. (2)
g.) What general conclusion can you make from this experiment? (2)
h.) Name at least 3 controlled variables in this experiment. (3)
Question 3
A student investigated the effect of acid rain on seed germination. Covered trays, each containing
pea seeds on damp filter paper, were watered with a range of solutions. Every two days, the student
recorded the number of seeds which had germinated. The results are shown in the table below.
Tray 1 Tray 2 Tray 3 Tray 4
Number of seeds 42 47 42 60
Watering solution
Water only
(Control)
pH 7.0
Dilute sulphuric
acid
pH 4.0
Dilute nitric acid
pH 3.5
Dilute sulphuric
and nitric acid
pH 4
Number of seeds germinated
Day 1 0 0 0 0
Day 3 0 0 0 0
Day 5 3 0 0 0
Day 7 38 10 19 6
Day 9 38 37 34 12
a.) State the independent variable in this investigation. (1)
b.) State two variables that would have been controlled in the investigation in order to produce a
fair test. (2)
c.) Suggest two ways in which the student’s experimental design could be improved. (2)
d.) According to the results obtained, which solution appeared to have the least effect on
germination of the seeds? Explain why. (2)
e.) Outline one harmful effect of acid rain on organisms in the environment. (1)
Links
www.biologycorner.com/lesson-plans/ecology
http://www.practicalecology.com.au/
http://www.skoool.ie/