Grade 6 Science: Ecosystems

Flashcards covering biotic and abiotic factors, trophic levels, energy flow, food chains and webs, ecological relationships, ecosystem types, and human impacts from Grade 6 Science.

What is an ecosystem?

An ecosystem is a community of living organisms (plants, animals, and microbes) interacting with one another and with the non-living physical environments surrounding them.

What are biotic factors in an ecosystem?

Biotic factors are the living or once-living parts of an ecosystem that directly or indirectly affect other organisms, such as plants, animals, fungi, bacteria, algae, decaying leaf litter, and insect larvae.

What are abiotic factors in an ecosystem?

Abiotic factors are the non-living physical and chemical elements in the environment that shape the habitat, such as sunlight, water, soil, air (oxygen & $CO_2$), temperature, wind, minerals, pH, and climate.

How do biotic and abiotic factors interact during photosynthesis and respiration?

Plants rely on sunlight, carbon dioxide, water, and soil nutrients to make food through photosynthesis, while animals depend on oxygen to breathe and water to drink.

How do producers (autotrophs) obtain their energy?

Producers create their own food by using sunlight, water, and carbon dioxide through photosynthesis to synthesize glucose (sugar).

How are herbivores, carnivores, omnivores, and scavengers defined?

Herbivores eat only plants; carnivores eat other animals; omnivores eat both plants and animals; and scavengers consume dead or decaying animals they did not hunt themselves.

What is the functional difference between decomposers and detritivores?

Decomposers (fungi and bacteria) release enzymes to chemically decompose organic matter, returning nitrogen, phosphorus, and minerals back into the soil and water, while detritivores (earthworms, millipedes, woodlice) physically consume and fragment organic debris.

What is the sequence of the example terrestrial food chain provided in the study guide?

Sun ➔ Grass (Producer) ➔ Grasshopper (Primary Consumer) ➔ Frog (Secondary Consumer) ➔ Snake (Tertiary Consumer) ➔ Hawk (Apex Predator) ➔ Decomposers.

What is the main difference between a food chain and a food web?

A food chain is a simple, linear sequence showing direct paths of energy transfer, whereas a food web is a complex network of interconnected food chains representing actual feeding relationships in a habitat.

What does the $10\%$ Energy Rule state?

When energy moves from one trophic level to the next, only about $10\%$ of the energy is stored in the body of the consumer, while the remaining $90\%$ is lost as metabolic heat, movement, digestion, and waste.

What is mutualism, and what are the examples provided?

Mutualism ($+ / +$) is a relationship where both species benefit from each other. Examples include bees collecting nectar while pollinating flowers, and clownfish and sea anemones.

What is commensalism, and what are the examples provided?

Commensalism ($+ / 0$) is a relationship where one organism benefits while the other is neither helped nor harmed. Examples include orchids growing on trees and barnacles attached to a whale's skin.

What is parasitism, and what are the examples provided?

Parasitism ($+ / -$) is a relationship where one organism (parasite) benefits by living on or in another (host), harming it. Examples include ticks or fleas on dogs, tapeworms in human intestines, and mosquitoes.

How do predation and competition differ?

Predation ($+ / -$) occurs when one organism (predator) hunts, kills, and eats another (prey), whereas competition ($- / -$) occurs when two or more organisms compete for limited resources like food, water, territory, or sunlight.

What are the characteristics of the four terrestrial ecosystems listed in the guide?

Tropical Rainforests have high biodiversity and heavy rainfall; Deserts have low rainfall and extreme temperatures; Grasslands/Savannas are dominated by grasses with periodic droughts; and Forests/Taiga feature deciduous trees or evergreen conifers with cold winters.

What are the two major categories of aquatic ecosystems and their sub-types?

Freshwater ecosystems include lakes, rivers, ponds, and streams; Marine ecosystems include coral reefs, open ocean, estuaries, and mangroves.

What five major threats to ecosystems are highlighted in the guide?

Deforestation & Habitat Loss, Pollution, Invasive Species (e.g., cane toad), Overhunting & Overfishing, and Climate Change.

What happens to an ecosystem when decomposers are absent?

Dead plant and animal material accumulates, and essential organic nutrients such as nitrogen, phosphorus, and minerals are not returned to the soil and water.