§-Module

Homeostasis (Module 2)

8 dot points across 8 inquiry questions, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

How do organisms keep their internal environment stable when conditions change?

Homeostasis involves a stimulus-response model in which a change in external or internal environmental conditions is detected and appropriate responses occur via negative feedback; in vertebrates, receptors and effectors are linked via a control centre by nervous or hormonal pathways, or both

TASC Biology Level 3 (BIO315124, criterion 6): what homeostasis is, the stimulus-response model (stimulus, receptor, control centre, effector, response), negative feedback, tolerance limits, and how nervous and hormonal pathways link receptors to effectors.

7 min read →

How are nerve impulses generated, conducted and passed between neurons?

Neural pathways consist of cells that transport nerve impulses from sensory receptors to neurons and on to effectors: the passage of nerve impulses involves transmission of an action potential along a nerve axon, and synaptic transmission by neurotransmitters and signal transduction

TASC Biology Level 3 (BIO315124, criterion 6): neuron structure, how the resting potential is maintained, the stages of an action potential (threshold, depolarisation, repolarisation, hyperpolarisation) and the ion channels involved, and how neurotransmitters carry the signal across a synapse.

9 min read →

How do hormones carry messages that change the activity of target cells?

Hormones alter the metabolism of target cells, tissues or organs by increasing or decreasing their activity; in animals, most hormones are produced in endocrine glands as a result of nervous or chemical stimulation and travel via the circulatory or lymph system to the target cells, tissues or organs

TASC Biology Level 3 (BIO315124, criterion 6): what hormones are, how endocrine glands release them in response to nervous or chemical stimulation, how they travel in the blood and act only on target cells with matching receptors, and the three hormones the course names: insulin, glucagon and ADH.

7 min read →

How do humans keep their body temperature within a narrow range?

Analyse thermoregulation in humans, including stimulus-response models, feedback loops and the associated messages and organ structures

TASC Biology Level 3 (BIO315124, criterion 6): how the hypothalamus and skin thermoreceptors detect temperature change, and how vasodilation and vasoconstriction, sweating, piloerector muscles, shivering and behaviour return body temperature to normal by negative feedback.

7 min read →

How is blood glucose kept within a narrow range?

Analyse glucose regulation in humans, including stimulus-response models, feedback loops and the associated hormones (insulin and glucagon) and organ structures

TASC Biology Level 3 (BIO315124, criterion 6): how the pancreas detects changes in blood glucose and releases insulin or glucagon, how the liver and body cells respond, the negative feedback loops for high and low blood glucose, and a general understanding of type 1 and type 2 diabetes.

7 min read →

How do the hypothalamus, ADH and the kidneys keep the body's water balance stable?

Analyse osmoregulation in humans, including stimulus-response models, feedback loops and the associated hormone (antidiuretic hormone) and organ structures, including kidney nephron function

TASC Biology Level 3 (BIO315124, criterion 6): the structure of the nephron, filtration and reabsorption, the components of urine, and how the hypothalamus and ADH adjust water reabsorption in the collecting ducts by negative feedback when the body is dehydrated or has too much water.

9 min read →

How does water move from the roots to the leaves, and what affects the rate of transpiration?

Investigate the transport of water from the roots via xylem (involving root pressure, cohesion of water molecules and transpiration) to the leaves and the factors that influence the rate of transpiration (light intensity, temperature, wind and humidity)

TASC Biology Level 3 (BIO315124, criterion 6): how water enters root hair cells, moves up the xylem by root pressure, cohesion and transpiration pull, and leaves through stomata, and how light intensity, temperature, wind and humidity change the rate of transpiration, including potometer experiments.

8 min read →

How do desert animals and xerophytes maintain water balance in arid environments?

Understand the various mechanisms that animals and plants use to maintain water balance, involving structural features and behavioural and physiological responses, in an arid environment (desert animals and xerophytes)

TASC Biology Level 3 (BIO315124, criterion 6): the structural, behavioural and physiological ways desert animals and xerophytes reduce water loss and gain water, with Australian examples such as the spinifex hopping mouse, the thorny devil, spinifex grass, eucalypts and acacias.

7 min read →