Biology: DNA, Systems, and Exchange

Construct and interpret labelled models of DNA and RNA that distinguish their nucleotide components, bases, strand structure, and biological functions.

Determine complementary DNA and mRNA sequences by applying the base-pairing rules A–T, A–U, and C–G.

Trace gene expression from DNA through transcription and translation to a polypeptide, explaining the roles of mRNA, tRNA, and rRNA and where each process occurs.

Explain how an enzyme’s active-site shape determines substrate specificity and predict how a change in enzyme shape affects its function.

Predict the movement of substances by diffusion, osmosis, or active transport from concentration information, including when ATP is required.

Explain how surface-area-to-volume ratio, short exchange distances, cell specialisation, and the cell–tissue–organ–system hierarchy enable multicellular organisms to function.

Trace blood through pulmonary and systemic circulation and predict changes in oxygen and carbon dioxide at the lungs and body tissues, linking exchange to alveolar and capillary adaptations.

Trace the digestion and absorption of carbohydrates, proteins, and lipids, linking enzyme action and the structures of folds, villi, microvilli, capillaries, and lacteals to efficient absorption.

Trace filtrate through a nephron and distinguish filtration, selective reabsorption, and excretion by predicting the fates of water, glucose, amino acids, urea, blood cells, and proteins.

Predict changes in ADH secretion, kidney water reabsorption, urine concentration, and blood water concentration during dehydration and excess water intake.