Year 9 Biology 2025

Ecology

The study of how living things interact with each other and their environment.

Ecosystem

A community of living things and their non-living surroundings working together.

Biome

A large region with a specific climate and types of plants and animals (e.g., desert, rainforest).

Community

All the different species living together in one area.

Population

A group of individuals of the same species living in one place.

Habitat

The natural home or environment of an organism.

Competition

When organisms fight for the same resources like food, water, or space.

Predation

When one organism (the predator) hunts and eats another (the prey).

Symbiosis

A close long term relationship between two different species.

Mutualism

A type of symbiosis where both species benefit.

Commensalism

A relationship where one species benefits and the other is not affected.

Parasitism

A relationship where one species benefits and the other is harmed.

Trophic level

A step or level in a food chain (e.g., producer, primary consumer, secondary consumer).

Heterotroph

An organism that gets its food by eating other organisms.

Autotroph

An organism that makes its own food, usually by photosynthesis.

Biomass

The total mass of living material in an area or ecosystem.

Chemical energy

Energy stored in the bonds of chemical substances like glucose.

Osmosis

The movement of water across a membrane from an area of low concentration to high concentration.

Transpiration

The process of water moving through a plant and evaporating from the leaves.

Xylem

Plant tissue that carries water and minerals from roots to leaves.

Phloem

Plant tissue that transports sugars and nutrients around the plant.

Neuron

A nerve cell that carries messages around the body.

Axon

The long part of a neuron that carries electrical messages away from the cell body.

Dendrite

Branch-like parts of a neuron that receive signals from other cells.

Synapse

The tiny gap between neurons where messages are passed using chemicals called neurotransmitters.

Central Nervous System (CNS)

The brain and spinal cord; it controls most body functions.

Reflex arc

The pathway that controls an automatic, fast response to a stimulus.

Stimulus

A change in the environment that causes a response.

Receptor

A structure that detects a stimulus (e.g., in the eyes, skin, or ears).

Hormone

A chemical messenger made by glands that travels in the blood to control body functions.

Pituitary

The "master gland" that controls other glands and many body processes.

Thyroid

A gland in the neck that controls metabolism and energy use.

Adrenal Glands

Glands that release adrenaline to prepare the body for "fight or flight."

Sensory neuron

Carries messages from receptors to the CNS.

Relay neuron (interneuron)

Passes messages within the CNS (brain and spinal cord)

Motor neuron

Carries messages from the CNS to muscles or glands (effectors).

Effector

A muscle or gland that responds to a message from the nervous system.

Glucose

A simple sugar used by cells for energy.

Oxygen

A gas needed for cellular respiration.

Carbon dioxide

A gas produced as a waste during respiration. Removed through exhalation.

Water

A product of respiration and essential for life processes.

Energy

The ability to do work; released during respiration.

Homeostasis

Keeping internal conditions (like temperature or blood sugar) stable.

Negative feedback

A process that reverses a change to keep conditions stable.

Stimulus response model

Describes how the body detects and responds to changes (stimulus → receptor → modulator → effector → response).

Modulator

The control centre that processes information and sends instructions (e.g., brain or spinal cord).

Pancreas

An organ that helps control blood sugar by producing insulin and glucagon.

Glycogen

The stored form of glucose in the liver and muscles.

Insulin

Hormone that lowers blood sugar levels.

Glucagon

A hormone that raises blood sugar levels.

Hypothalamus

Part of the brain that controls temperature, hunger, and other automatic functions.

Mucous

A sticky substance that traps dust and germs.

Phagocytosis

When white blood cells surround and engulf (eat) harmful microbes.

Antigen

A molecule on a pathogen that triggers an immune response.

Antibodies

Proteins made by the immune system to attack specific antigens.

Lymphocytes

White blood cells that produce antibodies and help fight infection.

Abiotic Factors

The non-living parts of an environment such as sunlight, temperature, water, and soil.

Biotic Factors

Fire-stick farming

A traditional Indigenous Australian practice of using controlled burns to manage the land, promote new plant growth, and attract animals for hunting.

Goitre

An enlargement of the thyroid gland, usually caused by a lack of iodine in the diet or other thyroid problems.

Estrogen

Produced by the ovaries in females, responsible for the development of female secondary sexual characteristics and regulation of the menstrual cycle.

Testosterone

Produced mainly by the testes in males, responsible for the development of male secondary sexual characteristics and supporting sperm production.

Thyroxine

Hormone produced by the thyroid gland, which controls metabolism, growth, and development in the body.

Melatonin

Produced by the pineal gland in the brain, which helps regulate sleep.