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 4

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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/