VCE Biology Units 3 and 4

Examine how cell structure underpins function, aligning with core concepts in VCE biology units 3 and 4.

Investigate biomacromolecules, their structural features, and their functions within biological systems. Examine how these large molecules influence cellular processes and overall biology.

transcription by RNA polymerase copies DNA into mRNA, introns are removed and exons joined to form mRNA, which is translated into a polypeptide that folds into a protein.

Learn how diffusion, osmosis, facilitated diffusion, and active transport move substances across membranes. The video explains gradients, water flow through channels, and energy-driven transport.

Photosynthesis converts light energy into chemical energy to form glucose through two stages: light-dependent and independent, using chlorophyll and a cake analogy to show inputs like water and carbon dioxide.

Explores glycolysis, the citric acid cycle, and the electron transport chain, showing how glucose converts to ATP, with CO2 release and proton-driven ATP synthesis across the inner mitochondrial membrane.

Explore how the nervous and endocrine systems maintain homeostasis via sensors and effectors, using negative feedback with insulin and glucagon, and positive feedback like uterine contractions.

Explore neuron structure, from the nucleus in the cell body to the axon and dendrites, and learn how Schwann cells support axons while distinguishing sensory, interneurons, and efferent neurons.

Explore neuron networks, including divergent networks where one pre-snap neuron connects with many posts and active neurons, and convergent networks where many pre-snap neurons connect with one person.

Explore how the central nervous system, brain and spinal cord, integrates sensory input with motor responses, and how the autonomic nervous system—sympathetic and parasympathetic—regulates muscles, glands, and digestion.

Explore brain structure and function, from brain stem and cerebellum regulating breathing and balance to the thalamus and hypothalamus directing sensory input and hormonal homeostasis.

hormones travel through the bloodstream and trigger actions in distant cells; peptide and protein hormones bind cell-surface receptors, while steroid hormones cross membranes to act inside cells.

Explore how plant hormones regulate cell elongation and cause the plant to bend toward light, with xylem transport and environmental factors driving the response.

Auxin, a plant hormone, diffuses and elongates existing cells on one side of the shoot. Uneven distribution triggers growth toward the light, producing positive phototropism.

Explore the three lines of defense in immunity, from phagocytes and interferon in the innate response to antibodies, B and T cells, and memory cells in the adaptive response.

Explore the first line of defense in the immune system, detailing non-specific barriers like mucous membranes, skin, stomach acids, and natural flora, and contrast with specific immunity.

The second line of defense activates phagocytes such as macrophages and neutrophils, plus natural killer cells to engulf pathogens via phagocytosis, while complement and interferon coordinate inflammation and antiviral responses.

Explore the third line of defense with B cells and T cells. Learn how B cells produce antibodies and memory cells, while T cells activate other immune cells.

Explore the structure of an antibody, including heavy and light chains, the variable region that binds antigens, and the constant region that engages macrophages.