GRADE 9 Integrated Science – The interdependence of life Quiz

Interdependence means organisms (plants, animals, microbes) and the physical environment interact and depend on each other for food, shelter, water and other needs.

A food chain begins with producers (plants) that make food, followed by herbivores that eat plants, then carnivores that eat herbivores.

Decomposers such as bacteria and fungi break down dead organic matter, releasing nutrients that plants reuse, which keeps nutrient cycles going.

Pollinators move pollen from one flower to another, allowing fertilisation and the formation of fruits and seeds, which boosts crop yields.

In mutualism both species benefit: acacia gives food/shelter to ants, and ants protect the tree from animals that would eat its leaves.

Parasitism is when one organism (the parasite) benefits at the expense of another (the host), as with ticks feeding on cattle.

Competition occurs when organisms need the same scarce resources (food, water, space), reducing availability and affecting survival or reproduction.

Removing a keystone predator can let herbivore numbers grow unchecked, leading to overgrazing and changes that harm the whole ecosystem.

As energy moves through trophic levels, most is used for life processes or lost as heat; only a small fraction (about 10%) becomes available to the next level.

Producers like algae and aquatic plants use sunlight to make food by photosynthesis and form the base of the pond food web.

Decomposers break down dead material, releasing nutrients back into the soil so plants can take them up and continue the cycle.

Legumes host Rhizobium bacteria in root nodules that convert atmospheric nitrogen into forms plants can use, enriching the soil.

Mycorrhizae are beneficial fungi that attach to plant roots, extending the root system and helping plants absorb more water and nutrients.

A habitat is the physical place an organism lives; its niche is how it fits into and uses resources in that environment (role, diet, behaviour).

Carrying capacity is the sustainable limit of organisms an area can support; exceeding it causes overgrazing, soil erosion and reduced productivity.

Removing trees exposes soil to rain, causing erosion and siltation of rivers which reduces water quality and raises flood risk downstream.

Invasive species grow rapidly, obstruct water flow, deplete oxygen, outcompete natives, and negatively affect fishing and local economies.

Community conservancies empower local people to manage and benefit from wildlife and land, improving conservation and livelihoods together.

Agroforestry integrates trees with farming, enhancing soil fertility, reducing erosion, conserving water, and providing multiple economic resources.

Wetlands act as natural filters, buffer floods, support biodiversity and fisheries, and are important for water regulation and livelihoods.

Many crops need pollinators for fruit set; fewer pollinators means lower yields and reduced food production and incomes for farmers.

A trophic cascade occurs when changes (e.g., removing predators) ripple through food webs, altering populations and ecosystem processes.

Vultures and other scavengers clean up carcasses, reducing disease risk and returning nutrients to the environment.

Seasonal migration follows resource availability—animals move to areas with fresh grass and water after rains to survive and reproduce.

Lichens are sensitive to air pollution; abundant, healthy lichens usually indicate cleaner air, making them useful bioindicators.