19: Ecosystems Flashcards
What is the definition of habitat?
The habitat is the place where organisms live.
What is ecology?
Ecology is the study of the inter-relationships between organisms and that between organisms and their envrionment.
What are all levels of organisation in ecological studies ranked from low to high?
Species, population, community, ecosystem, biome, biosphere
What does the term “species” refer to in ecological studies?
Species is the lowest level of classifying organisms. It consists of organisms that can interbreed and produce fertile offspring.
What does the term “population” refer to in ecological studies?
Population refers to a group of organisms of the same species living in the same habitat.
What does the term “community” refer to in ecological studies?
Community refers to all the populations of different species living in the same habitat.
What does the term “ecosystem” refer to in ecological studies?
An ecosystem is a natural unit of the living components (the organisms in a community) and the non-living components (the physical envrionment). These components interact to form a self-supporting, stable, yet dynamic syetem in a particular area.
What does the term “biome” refer to in ecological studies?
A biome is a complex of communities that occupies a large geographical area. It is characterised by a dominant type of plant, which is determined by the climatic comditions.
What does the term “biosphere” refer to in ecological studies?
Biosphere refers to the entire space on the Earth’s surface where organisms exist. It consists of the land, the water and the lower part of the atmosphere.
What is an example of a biome and its locations?
The savanna biome is located in Africa, India, the northern part of Australia and the middle part of south America.
At which ecological level should we study how the body features of the individuals of a species adapt to ther envrionment?
At the species level
At which ecological level should we study how environmental factors affect the number of a certain species?
At the population level
At which ecological level should we study the interaction among different species in a habitat?
At the community level
At which ecological level should we study the cycling of materials between organisms and their environment?
At the ecosystem level
At which ecological level should we study the impact of human activity on global ecological processes like global warming?
At the biosphere level
What are the features that are essential to keep the ecosystem self-supporting, stable, and dynamic?
Cycling of materials, interactions of organisms with one another and with the envrionment, and energy input
How does the cycling of materials maintain the properties of an ecosystem?
Useful elements like carbon and nitrogen inside organisms are not lost from the ecosystem. Instead, they are cycled through the ecosystem when the organisms carry out photosynthesis, respiration, excretion, egestion or when they die. Thus, an ecosystem does not require the supply of extra materials, explaining why it is stable and self-supporting.
How does feeding maintain the dynamic properties of the ecosystem?
Feeding is a form of material cycling and interaction of organisms with one another and with the envrionment, making an ecosystem dynamic. In feeding, materials are transferred from one organism to the other in the form of food.
Inorganic materials in the envionment may be absorbed by the organisms and may be converted to organic matter through autotrophic nutrition. Materials may be released back to the envrionment through respiration, excretion and decomposition of dead organic matter.
How does competition maintain the dynamic properties of the ecosystem?
Some species may compete for common resources, such as living space, which is a kind of interaction of organisms with one another, making the ecosystem dynamic.
How does the adaptation of organisms maintain the dynamic properties of the ecosystem?
Organisms shows different adaptations in order to live in specific envrionments. On the other hand, organisms also affect their physical environment. For example, they may take up substances and release waste into the environment. They may also modify their physical environment by speeding up erosion or stabilising the substratum.
Why is the sun required to sustain an ecosystem?
Energy in an ecosystem cannot be cycled. As the survival of organisms require a continuous supply of energy, there must be a continuous input of energy into the ecosystem, which usually comes from the sun.
How is energy transferred from one organism to another and how is it lost?
Energy is transferred from one organism to another in the form of food and lost as heat.
What are the two components making up an ecosystem?
The abiotic factors and the biotic community
How does temperature affect the distribution and behaviour of organisms?
Metabolic reactions in the cells are catalysed by enzymes, which only work best within a narrow range of temperatures.
How do homoiotherms and poikilotherms respond to a change in environmental temperature?
Homoiotherms retain a steady body temperature while poikilotherms’ body temperature fluctuates with the envionmental temperature.
What are some adaptations by animals living in warm areas?
The evaporation of water from sweat, and panting in dogs which evaporates water from saliva
What are some adaptations by animals living in cold areas?
hibernation; thick layer of subcutaneous fat under the skin acting as insulators; penguins huddle together to reduce the collective surface-area-to-volume-ratio
Name 4 types of bacteria classified according to living temperature.
from low to high: psychrophiles, mesophiles, thermophiles, hyperthermophiles
How does light affect plants?
Light intensity mainly affects the rate of photosynthesis in plants, while the day length affects the flowering of plants
What is the difference between diurnal animals and nocturnal animals?
diurnal animals are active during the day and rest at night, while nocturnal animals are active at night.
What are the adaptations of organisms in habitats with limited water supply?
They develop special mechanisms to retain water in their body and reduce water loss, such as spiny leavs and waxy skin on cacti.
How do wind speed and water current affect the distribution of organisms?
In terrestrial ecosystems, strong wind may blow the soil away, making the soil not suitable for the growth of large plant species.
In aquatic ecosystems, strong winds may generate strong waves that wash immobile or slow-moving animals away.
What are the adaptations of organisms in windy habitats or fast-flowing water?
They develop body structures to hold themselves firmly onto the substratum. In aquatic habitats, they may have a streamlined body to reduce resistance while moving in water.
What are 2 other abiotic factors water current can influence?
Oxygen level: the higher the speed of water current, the higher the oxygen level in the water.
Particle size of substratum: the higher the speed of water current, the larger the particle size since smaller particles are washed away.
Name 3 abiotic factors influencing oxygen level in aquatic habitats.
Temperature, water current, organic matter
How does temperature affect the oxygen level in aquatic habitats?
The higher the temperature, the lower the oxygen level, since the solubility of oxygen in water decreases as temperature increases.
How does the speed of water current affect the oxygen level in aquatic habitats?
The higher the speed of the current, the higher the oxygen level, since splashes increase the contact area of water with oxygen.
How does the amount of organic matter affect the oxygen level in aquatic habitats?
The presence of organic matter lowers the oxygen level, since the decomposition of organic matter uses oxygen.
What is salinity and its significance?
Salinity refers to the concentration of dissolved salts and ions in water. It directly determines the water potential and hence the availability of water and minerals to organisms.
Where does salinity have a large fluctuation daily?
In the intertidal zone
What is the meaning of substratum?
Substratum refers to the material that the organisms are growing on or attaching to. It varies from bare rock to soil of different particle sizes, including any stable surface provided by organisms like tree trunks and coral reefs.
What are the characteristics of soil with small particles?
The air spaces among the particles are small and the concentration of oxygen in the soil is lower. The soil is easily flooded with water (ie becomes water-logged).
How is humus formed?
Humus is formed from the decomposition of organic matter by microorganisms in soil.
What are the characteristics of humus?
It is the major source of nutrients in soil for plant growth. It can hold a large amount of moisture, therefore increasing the soil’s capacity to withstand drought conditions.
How are abiotic factors altered by plant layers in a woodland?
Light intensity and temperature differ at different layers of a woodland. The canopy layer forms a shelter against strong wind and heavy rain. This helps prevent soil erosion and reduce runoff.
How are abiotic factors altered by tree roots and humus in a woodland?
The tree roots are deep. The extensive root system holds the soil particles together. This helps prevent soil erosion and reduce runoff. A thick layer of humus on the ground layer maintains fertility of the soil.
Name two major types of coastal ecosystems.
rocky shores and mangroves
What are the characteristics of the substratum of rocky shores?
They have a hard substratum since the habitat is exposed to strong waves.
Name 5 zones a rocky shore can be divded into vertically.
from high to low: splash zone, high tide zone, mid tide zone, low tide zone, subtidal zone
How is zonation seen in rocky shores?
Specific groups of organisms are found in each zone.
What are the adaptations of organisms living in rocky shores?
Many organisms develop ways to attach themselves firmly to the rocks, such as muscular foot. Most of them also have a hard shell for protection and to prevent them from drying up. Some organidmd stay away from strong waves by hiding themselves in rock crevices.
What are the characteristics of mangroves?
Most of them are located in sheltered bays, which are subject to tidal actions. There is a continuous exchange of waster from the river and the sea. Therefore, the salinity of the mud fluctuates throughout the day.
Organic matter can easily accumulate in the soft mud and the oxygen level is low.
