STMF Biology exam year 9 2025

Biotic Environment

Living components that interact with each other and abiotic (non-living) components in an environment.

Indigenous (native) species

Evolved and are an integral part of the natural system.

Alien/exotic species

Introduced into an ecosystem, potentially causing disruptions and displacement of native organisms.

Producers (autotrophs)

Convert inorganic molecules into organic compounds.

Consumers (heterotrophs)

Rely on other living organisms for food.

Herbivores

Primary consumers that eat plants.

Carnivores

Secondary consumers that feed on herbivores.

Omnivores

Eat both plants and animals; may be secondary or tertiary consumers.

Decomposers (detritivores)

Decompose plants, animals, and faeces, returning nutrients to the environment.

Endemic Species

Living organisms found only in one area with specialized adaptations.

Symbiosis

Close association between two organisms where one or both benefit.

Mutualism

Beneficial to both organisms.

Commensalism

One species benefits, the other is neither harmed nor helped.

Parasitism

One species (parasite) benefits, the other (host) is harmed.

Endoparasites

Live inside the host.

Ectoparasites

Live outside the host.

Competition

Occurs when organisms depend on a common resource that is in short supply.

Intraspecific competition

Competition between organisms of the same species.

Interspecific competition

Between organisms of different species.

Populations

A group of organisms of the same species living together in the same habitat and capable of interbreeding.

Carrying capacity

The maximum number of individuals of a species that can be supported by available resources.

Ecology

Study of interactions between biotic (living) and abiotic (non-living) components of an environment.

Chemical Pest Control

Effective but harmful to the environment and humans.

Biological Pest Control

Uses other organisms (predators, parasites, pathogens) to limit pest numbers; less harmful to the environment.

Xylem and phloem

Form vascular bundles, providing both transport and support.

Xylem Vessels

Transport water and minerals from roots to leaves.

Phloem Vessels

Transport food (sucrose and amino acids).

Transpiration

Water loss through stomata in leaves.

Diffusion

Passive movement from high to low concentration; linked to kinetic energy.

Osmosis

Passive diffusion of water from dilute to concentrated solution through a semi- permeable membrane.

Active Transport

Movement requiring energy from low to high concentration.

Hypotonic Solution (Animal Cells)

Water enters the cell, causing it to burst (lysis).

Hypertonic Solution (Animal Cells)

Water leaves the cell, causing it to shrivel.

Isotonic Solution (Animal Cells)

No net water movement.

Hypotonic Solution (Plant Cells)

Water enters, cell becomes turgid, turgor pressure increases.

Hypertonic Solution (Plant Cells)

Water exits, cell becomes flaccid (wilting), plasmolysis occurs.

Breathing (ventilation)

Moving air in/out of the lungs.

Gas exchange

Transfer of gases from high to low concentration in alveoli (humans) or leaves (plants).

Cellular respiration

Releasing energy from glucose; may or may not require oxygen.