Ecosystems Flashcards
What do living organisms do in order to survive and reproduce!
Interact with other organisms and the environment in which they live
What is an environment?
The sum total of the biological, physical and chemical conditions surrounding an organism
What is an ecosystem?
A particular area in which living components interact with one another and with non-living components
What is another name for the living components in an ecosystem?
Biotic
What is another name for the non-living components in an ecosystem?
Abiotic
What is the size of an ecosystem?
It can be a giant rainforest, or a tiny drop of water
What is ecology?
The study of relationships and interactions between living organisms and between the organism and the natural environment in which they occur
How many abiotic factors are there?
Seven
What are the seven abiotic factors?
Physiographic Edaphic Light Temperature Water Atmospheric gases Wind
What are the climatic factors?
The collective term for wind, temperature, light, water and atmospheric gases
What are three physiographic factors?
Aspect
Slope
Height above sea level
What is aspect?
Slope direction
It refers to the position of an area in relation to the sun
How does aspect influence vegetation?
One side of a slope gets more sunlight than another
Sun-loving vegetation therefore prefers this slope
Shade plants prefer the other side
Which side of a mountain (in SA) gets more sunlight?
North
What is slope?
How steep or flat a landscape is
What does slope affect?
The rate of water run-off
How does the rate of water run-off affect vegetation?
More run-off means more nutrients are washed away
There are fewer nutrients available
Few plants and animals are present
What kind of slope increases the rate of water run-off?
Steep
What kind of slope decreases water run-off?
Gentle
What kind of weather can be found high above sea level?
Extreme
Strong winds
Snow
What are edaphic factors?
Soil factors
What are five edaphic factors?
Type of soil Soil air Water-holding capacity Humus content pH
What are the three types of soil?
Clay
Loam
Sand
What kinds of particles are found in clay?
Tiny
What kinds of particles are found in loam?
Slightly larger particles
What kinds of particles are found in sandy soil?
Coarse, large particles
What is soil texture?
It refers to how coarse or fine the soil is
What is soil air?
Spaces between soil particles that are filled with air
Why is soil air important?
It is vital for the survival of soil organisms
Which type of soil has the most soil air?
Sandy soil
When soil has soil air, what is it referred to as?
Well-aerated soil
Why is soil air important for plants?
The pockets of soil air allow space for plant roots to push through
What is water-holding capacity?
How much water is retained in the soil
Which type of soil has the greatest water-holding capacity?
Clay
Why does clay have the best water holding capacity?
The tiny particles are close together, trapping the water
What happens when soil (such as sand) has a low water-holding capacity?
The water drains through the soil
What is leaching?
Leaching occurs when water drains through soil and takes nutrients with it
Why isn’t clay soil suitable for pant growth, even though it has a great water-holding capacity?
The plant roots rot because the water does not drain away
What type of soil is the most suitable for plant growth?
Loam
Why is loam suitable for plant growth?
Sufficiently aerated
Has a good water-holding capacity, but it can still drain
It contains sufficient nutrients
What is humus?
Decayed plant and animal matter
Why is humus good in soil?
It increases the available nutrients in soil
Increases the soil’s water-holding capacity
What is soil with sufficient nutrients in it called?
Fertile soil
What colour is soil with a high humus content?
Dark brown
How does pH affect plant growth?
Different plants prefer different pH
Which plants prefer acidic soil?
Azaleas
Proteas
Which plants prefer alkaline soil?
Succulents
What kind of pH do most plants prefer?
Neutral (7)
How does leaching affect pH?
Leaching causes the soil to become acidic
Where does leaching often occur?
In high rainfall regions with sandy soil
Why do plants need light?
For photosynthesis
Why can excessive light be detrimental to plants?
It can damage tissues
What is day length?
The duration of time that plants are exposed to light
What is photoperiodism?
The effect of day length on the growth of the plant
What are short-day plants?
Plants that will only flower if the day length is shorter than 12 hours
What are long-day plants?
Plants that require a day length of over 12 hours in order to flower
What are neutral plants?
Plants that are not affected by day length
What else does light intensity affect?
The growth movement and turgor of a plant
What is meant by growth movement?
The time at which flowers open or close
What happens to vygies when light intensity decreases (gets darker)?
They close
What happens to the evening primrose when light intensity decreases (gets darker)?
It opens
What are sun plants?
Plants in which photosynthesis takes place at a high light intensity
They need more light
What are shade plants?
Plants in which photosynthesis takes place at a lower light intensity
How are animals affected by light?
Some animals prefer the dark
Many animals hunt at night and rest during the day
What are nocturnal animals?
Animals that are most active at night
What are ectothermic animals?
Animals whose body temperature depends on the temperature of their environment
What do many ectothermic animals do?
Hibernate in winter
What is hibernation?
A deep sleep during which the metabolism and heart rate of the animal decrease
When do most hibernations occur?
During winter when the conditions are very cold
What are endothermic animals?
Animals that can keep their body temperature constant despite their environmental temperature
Do ectothermic animals hibernate?
Some do
What is another thing that ectothermic animals can do in winter?
Migrate to areas with a warmer climate
What are annuals?
Plants that complete their life cycle in one season and survive the winter in the form of seeds
What do deciduous trees do during winter?
They lose their leaves
Why do deciduous trees lose their leaves in winter?
To reduce their metabolism in order to survive
What are epigeal parts?
Parts of a plant that are above ground
How do some plants hibernate?
They lose their epigeal parts and hibernate in the form of bulbs, tubers or rhizomes
What is a hydrophyte?
A plant that is adapted to grow in water
What are some examples of hydrophytes?
Water lilies
Hyacinths
What are mesophytes?
Plants that are adapted to live in areas with a moderate water supply
What are some examples of mesophytes?
Fruit trees
Poplars
Wheat
Maize
What are xerophytes?
Plants that are adapted to live in areas where there is very little water
What is another name for xerophytes?
Succulents
What are some examples of xerophytes?
Hoodie gordonii
Aloe Vera
What are the characteristics of xerophytes?
Thick, fleshy leaves to store water Small leaves Sunken stomata Thick cuticles Well developed root systems
How is the kangaroo rat adapted to live without water?
It obtains water from its food
What animals can live without water for long periods?
Camel
Springbok
Gemsbok
How is the camel’s excretory system adapted to conserve water?
They excrete urine in the form of crystals
How does water affect earthworms?
They need damp soil to survive
How are insects adapted to conserve water?
They have a hard exoskeleton to prevent dehydration
How are reptiles adapted conserve water?
They are covered in hard, dry scales to prevent water loss
What are aquatic animals?
Animals that are adapted to live in water
How are fish adapted to their environment?
They have gills for gaseous exchange
They have fins for swimming and balance
What is the composition of the atmosphere?
78% Nitrogen
21% Oxygen
0,04% Carbon dioxide
0,96% other
Why is Oxygen important for life on earth?
Apart form anaerobic bacteria, all organisms need it for cellular respiration
Why is CO2 important for plants?
It is required for photosynthesis
How do terrestrial organisms obtain O2?
Directly from the air
How do aquatic organisms obtain O2?
They absorb it from the water (apart from sea mammals, they come up for air)
How do soil organisms acquire O2?
Soil air
Which substance has the most O2?
Air contains much more O2 than water
Where do plants get Nitrogen from?
They absorb it form the soil
In which form do plants obtain Nitrogen?
Nitrates NO3
How do animals obtain Nitrogen?
From the food that they eat
How are animals adapted for gaseous exchange?
They have respiratory organs with specialised gaseous exchange systems
What respiratory organs do birds and mammals have?
Lungs
What respiratory organs do fish have?
Gills
What respiratory organs do earthworms have?
Their moist, naked skins function as a gaseous exchange surface
How are most plants adapted for gaseous exchange?
They have stomata on their leaves and stems
How are woody plants adapted for gaseous exchange?
They have lenticels
How are aquatic plants adapted for gaseous exchange?
They have a thin epidermis and no cuticle
How are aquatic insects adapted for gaseous exchange?
They trap air bubbles between their body hairs for gaseous exchange
Give an example of an aquatic insect
Water beetle
What is wind?
Moving air
How does wind affect the environment?
They affect evaporation and transpiration, resulting in living organisms losing water more rapidly
They affect waves
What is the biotic component?
It includes all of the living organisms that occur in the ecosystem
What are the two groups within the biotic component?
The autotrophic component
The heterotrophic component
What is the autotrophic component?
Organisms which can produce their own food
What does the autotrophic component consist of?
All green plants
What is another name for the autotrophic component?
Producers
What is the heterotrophic component?
The group of organisms which cannot produce their own food
How do heterotrophs obtain food?
They are all directly or indirectly independent on the producers for the food
What is another name for the heterotrophic component?
The consumers
What are the four subdivisions of the consumers?
Primary consumers
Secondary consumers
Tertiary consumers
Decomposers
What are primary consumers?
Organisms that feed directly on plants
What is a herbivore?
An animal that has plants as a food source
What is an omnivore?
An organism that lives partially on plant matter and partially on animal matter
What type of animal can the primary consumer be?
Herbivore
Omnivore
What are secondary consumers?
Organisms that feed on the primary consumers
What are carnivores?
Meat eaters
They live only on animal matter
What are scavengers?
Organisms that eat the remains of dead animals
What kinds of animals can the secondary consumers be?
Carnivores
Scavengers
Omnivores
What are tertiary consumers?
Organisms that feed on the secondary consumers
What kinds of animals are the tertiary consumers?
Carnivores
What are decomposers?
Organisms that feed on dead organic matter
What do decomposers do?
They break down organic compounds into simple inorganic substances that are released back into the environment
What are examples of decomposers?
Saprophytic bacteria
Fungi
Why are decomposers important?
Without them, nutrients would not be released back into the environment
