Ecology Flashcards
What is ecology?
The study of relationships between living organisms and between organisms and their environment.
Ecologists study various ecosystems, which can vary in size from the biosphere to a single drop of water.
What is an organism?
One living individual.
Organisms can be of any type, including plants, animals, fungi, and microorganisms.
What is a population?
A group of organisms of the same species living in the same area at the same time.
Populations can vary greatly in size and density.
What is a community in ecology?
A group of different populations living and interacting with each other in a particular ecosystem.
Communities can include various species of plants, animals, and microorganisms.
Define a species.
A group of living organisms that can interbreed and produce fertile offspring.
Species are often defined by their genetic similarity and reproductive isolation.
What is a niche?
The role in which a species normally performs or the job of a living organism.
A niche encompasses how a species interacts with its environment, including its habitat and food sources.
Define habitat.
A particular environment in which a species normally lives or the home of a living organism.
Habitats can range from forests to deserts to aquatic environments.
What are producers in an ecosystem?
Organisms that make their own food, also known as autotrophs.
Examples include green plants, algae, and cyanobacteria.
What is photosynthesis?
The process by which plants manufacture sugar (glucose) from carbon dioxide and water using sunlight.
This process is essential for producing organic molecules in ecosystems.
What are consumers?
Organisms that are directly or indirectly dependent on autotrophs for their food, also known as heterotrophs.
Consumers cannot produce their own food and rely on other organisms.
List the types of consumers.
- Herbivores
- Carnivores
- Omnivores
- Detritivores
- Decomposers
Each type of consumer has a different source of food.
What are herbivores?
Consumers that feed on producers.
Examples include zebra, springbok, mice, aphids, and krill.
What are carnivores?
Consumers that feed on other consumers.
Examples include lions, cheetahs, eagles, ladybirds, and tuna.
What are omnivores?
Consumers that feed on both producers and consumers.
Examples include humans, dogs, ants, and sardines.
What are detritivores?
Consumers that feed on dead plants or animals.
Examples include woodlice and earthworms.
What are decomposers?
Heterotroph organisms that break down dead organisms and organic wastes into inorganic substances.
Examples include bacteria and fungi, also known as saprotrophs.
True or False: A tree only provides food for consumers.
False.
A tree also provides habitat for many organisms.
Fill in the blank: The living components of an ecosystem are called _______.
[biotic components].
These include all the living organisms within the ecosystem.
Fill in the blank: The non-living components of an ecosystem are referred to as _______.
[abiotic components].
These include elements like water, air, soil, and sunlight.
What is the primary purpose of food chains and food webs?
To describe the transfer of energy within an ecosystem
Food chains and webs show who eats whom and how energy and matter move through ecosystems.
What does an arrow in a food chain or food web indicate?
The direction of energy flow
The arrow always points towards the consumers.
What is the sequence of a typical food chain?
Producer → primary consumer → secondary consumer → tertiary consumer → decomposer
This sequence represents a single pathway of energy flow.
Why are food chains generally simpler than actual ecological interactions?
Most organisms consume and are consumed by more than one species
Food webs depict this complexity better than food chains.
What are trophic levels?
The feeding positions in a food chain or web
All food chains and webs have at least two or three trophic levels.
What is the maximum number of trophic levels typically found in ecosystems?
Five
Very large ecosystems, such as oceans, may have more.
How much energy is typically passed from one trophic level to the next?
About 10 percent
The remaining 90 percent is used for metabolic processes or lost as heat.
What explains the rarity of more than four trophic levels in a food chain or web?
The loss of energy at each trophic level
There is usually not enough energy left to support additional levels.
What are ecological pyramids used for?
To demonstrate changes in energy, biomass, or numbers within an ecosystem
They visually represent the distribution of energy or biomass at different trophic levels.
What does a pyramid of energy show?
How much energy is retained in the form of new biomass at each trophic level
This pyramid illustrates energy flow in an ecosystem.
What does a pyramid of biomass represent?
The amount of living or organic matter present in organisms at different trophic levels
It reflects the total biomass at each level.
What does a pyramid of numbers represent?
The number of individual organisms at each trophic level
This pyramid can be inverted or take other shapes due to size variation among organisms.
True or False: Pyramids of energy and biomass are normally upright.
True
Pyramids of numbers can vary in shape.
What is bioaccumulation?
The gradual accumulation of substances, such as pesticides or other chemicals, in an organism.
Bioaccumulation occurs when an organism absorbs a substance at a rate faster than it is lost or eliminated.
What is biomagnification?
The increased concentration of a poison in the tissues of tolerant organisms at successively higher levels in a food chain.
This phenomenon results in organisms at the top of the food chain having higher tissue concentrations of poisons and pollutants.
What are climatic factors in ecosystems?
Factors include light, temperature, water, wind, and air composition.
These factors play a crucial role in shaping the environment and the organisms that inhabit it.
How do strong winds affect ecosystems?
They speed up evaporation, assist in the pollination of plants, and help in the dispersal of seeds.
For instance, in the Western Cape, winds help disperse seeds of proteas that are released after a fire.
True or False: Environmental toxins can cause significant harm to ecosystems even at low levels.
True
Examples include long-term effects of low levels of environmental poisons like mercury.
Fill in the blank: _______ is the process when an organism absorbs a substance faster than it is eliminated.
[Bioaccumulation]
This process leads to the accumulation of harmful substances in the organism over time.
What is the main consequence of biomagnification in food chains?
Organisms at the top of the food chain have a higher concentration of toxins than those at lower levels.
This can lead to health risks for predators, including humans.
Name three climatic factors that influence ecosystems.
- Light
- Temperature
- Water
These factors are essential for the survival and growth of various organisms.
What role does wind play in seed dispersal?
Wind helps in the dispersal of seeds by blowing them further away from the parent plant.
This can increase the chances of germination in new areas.
Fill in the blank: _______ refers to the harmful effects that low levels of environmental poisons can have over time.
[Long-term effects]
Such effects can be observed in ecosystems affected by pollutants like mercury.
What are the main components of air?
78% nitrogen, 21% oxygen, 0.04% carbon dioxide, variable water vapour
The composition of air is crucial for understanding atmospheric science and biochemistry.
What cycle uses oxygen in cellular respiration and returns it through photosynthesis?
Oxygen cycle
This cycle is vital for the survival of aerobic organisms.
What is the role of carbon dioxide in the carbon cycle?
Product of cellular respiration and decayed organic matter
Plants remove carbon dioxide from the atmosphere during photosynthesis.
What is the nitrogen cycle important for?
Synthesis of proteins
All living organisms require nitrogen for protein synthesis.
How does the amount of water vapour in the air vary?
Remains fairly constant on average, varies greatly from place to place
High humidity levels are found in some areas, while others may have dry air.
What weather phenomena are caused by the condensation of water vapour?
Clouds, rain, and snow
Water vapour plays a crucial role in weather patterns.
What is essential for the process of photosynthesis?
Light
Producers like plants rely directly on sunlight for energy.
How do heterotrophs obtain energy?
By consuming plants or other heterotrophs
Heterotrophs depend on autotrophs for energy indirectly.
What process releases energy stored in sugars?
Cellular respiration
This process is critical for all organisms to obtain energy.
What is photoperiodism?
Plant growth affected by the length of the day
Some plants only flower when the day length reaches a certain duration.
What light condition do some plants need for optimal growth?
High levels of light or full sunlight
Other plants may thrive in shady conditions.
Define nocturnal.
Active during the night
Examples include bats and honey badgers.
Define diurnal.
Active during the daytime
Most birds and humans are diurnal.
Define crepuscular.
Active primarily during the twilight period
Examples include housecats and rats.
What is temperature’s effect on evaporation and transpiration?
Temperature affects the rate of evaporation and transpiration
Seasonal changes in weather are influenced by temperature variations.
How does temperature influence seed germination?
Germination of seeds requires warm temperatures
Seasonal variation in vegetation is linked to temperature.
What are the two types of temperature-related adaptations in animals?
Endothermic and Ectothermic
Endothermic animals maintain a constant body temperature, while ectothermic animals depend on environmental temperatures.
What is hibernation?
A winter sleep for the cold season
Hibernation is an adaptation for surviving cold temperatures.
What are annuals in the context of plant adaptations?
Plants that complete their life cycle in one season and survive harsh seasons as seeds
Annuals are adapted to quickly grow and reproduce before unfavorable conditions.
What do deciduous plants do during harsh seasons?
Lose leaves and reduce metabolism to survive
This adaptation helps them conserve energy and water.
What are bulbs, tubers, and rhizomes?
Plants with below-ground parts that survive harsh seasons or fire
These structures store nutrients and provide resilience against environmental stress.
What is the significance of water in living organisms?
Water is essential for all living organisms and is a major component of cells
About 80% of the human body and 90% of the plant body consists of water.
How is water distributed across the Earth?
Water is not evenly distributed; abundant in aquatic ecosystems and least abundant in deserts
This distribution affects ecosystem types and species adaptations.
What are xerophytes?
Plants that live in dry habitats or regions with low annual rainfall
Xerophytes are adapted to resist drought and cope with high temperatures.
What defines mesophytes?
Plants that need an average, regular supply of water
They thrive in moderate environments with consistent moisture.
What are hydrophytes?
Plants that live entirely or partially submerged in water or in very wet soil
These plants need to cope with a water surplus.
Fill in the blank: An extremely rare strategy is found in some plants that can dry out and come back to life when water is available, such as the _______.
resurrection plant
This ability allows certain plants to survive extreme drought conditions.
What are physiographic factors?
Factors relating to the physical geography of the environment that affect ecosystems, including slope, aspect, and altitude.
What does the term ‘aspect’ refer to in ecology?
The direction or side that a particular ecosystem is facing in relation to the sun, wind, or wave action.
How does aspect influence ecosystems in the Southern Hemisphere?
North-facing slopes receive more direct sunlight, making them warmer and drier, while south-facing slopes are cooler and wetter.
In the Southern Hemisphere, which slopes are typically sunnier and warmer?
North-facing slopes.
In the Northern Hemisphere, which slopes are hotter and sunnier?
South-facing slopes.
What is the effect of ecological aspect observed on the slopes of Devils Peak?
Newlands Forest is on the cooler, shadier south to southeast slopes, while scrubby fynbos vegetation is on the hotter, sunnier north-facing slopes.
What is meant by ‘slope’ in an ecological context?
The degree of incline or slope of the ground in an ecosystem.
How does slope affect soil fertility?
Steep slopes typically have less soil, leading to less fertile ecosystems due to greater runoff and soil erosion.
What is the definition of altitude?
The height above (or below) sea level.
What environmental conditions are associated with high altitude ecosystems?
More extreme weather, such as strong winds and snow, along with different temperatures and atmospheric gases.
How do plants and animals at higher altitudes adapt to their environment?
They have adaptations to survive harsher conditions.
Fill in the blank: South-facing slopes in the Southern Hemisphere are typically _______.
cooler and wetter.
True or False: At lower altitudes, the weather is generally more extreme and less sheltered.
False.
What types of vegetation are typically found on south-facing slopes in Cape Town?
Shade plants, such as ferns.
What happens to the amount of soil on steep slopes?
It is typically less, resulting in less fertile ecosystems.
What is one major consequence of greater runoff on steep slopes?
Greater soil erosion.
What are edaphic factors?
Soil factors including soil texture, soil air, soil water, humus content, and soil pH.
Edaphic factors are critical for understanding soil health and its capacity to support plant life.
What role does soil play in supporting plants?
Provides nutrients, anchors roots, and supplies drinking water.
Soil’s ability to absorb, release, and purify water is essential for plant health and ecosystem stability.
What is the estimated biodiversity in one hectare of soil?
Contains approximately 1020 kg of earthworms, 2700 kg of fungi, 1700 kg of bacteria, 150 kg of protozoa, and 1000 kg of arthropods and algae.
Biodiversity in soil is crucial for ecosystem functioning and nutrient cycling.
How many bacteria can one gram of soil hold?
One billion bacteria.
Only 5 percent of these bacteria have been discovered and described.
What is the significance of soil as a carbon sink?
Stores over three times more carbon than forests and other vegetation.
Soil plays a critical role in mitigating climate change.
What percentage of the world’s soil has been strongly degraded?
Seventeen percent.
Unsustainable agricultural practices are the main causes of land degradation.
How long does it take for 2.5 cm of topsoil to form?
500 to 1,000 years.
This long formation time highlights the importance of soil conservation.
What are the three main types of soil particles?
Clay, silt, and sand.
These particle sizes determine the soil texture and its properties.
What is loam soil?
A mixture of sand, silt, and clay.
Loam soils are generally more fertile and better for supporting various plant species.
What is a soil triangle used for?
To establish the kind of soil being investigated based on the percentages of each soil type.
The soil triangle helps visualize the relationship between different soil textures.
How are the percentages of soil types calculated in a sample?
By adding the soil sample to water, shaking it, allowing it to settle, and measuring the height of each layer.
This method relies on the different settling rates of soil particles.
What should the total percentage of soil types add up to when using a soil triangle?
Accurate calculations are essential for correctly identifying soil types.
True or False: Soil erosion has always occurred naturally.
True.
However, the rate of topsoil loss due to agriculture has surpassed natural formation rates since the 19th century.
What is soil air?
Trapped air between soil particles essential for soil organisms’ cellular respiration
Sandy soil has large particles and is well aerated, while clay soils are poorly aerated.
What is soil water?
Water that fills the air spaces between soil particles
Water is affected by cohesion (water attracts water) and adhesion (water attracts other substances).
How does soil type affect water drainage in sandy soils?
Sandy soils have large particles and small surface area, leading to easy drainage of water
Little adhesion of water to particles allows quick drainage.
How does soil type affect water drainage in clay soils?
Clay soils have tiny particles and large surface area, leading to poor drainage of water
High adhesion of water to particles retains water.
What is soil water retention?
The ability of soil to retain water
Different soil types retain water differently, affecting vegetation growth.
What is soil water drainage?
The ease with which water passes through soil
Quick draining soil is not suitable for water-loving plants; excessive retention can lead to waterlogging.
What is humus?
Dead and decaying organic matter in soil, rich in nutrients
Contains detritivores and decomposers, and holds onto water.