IB Biology Topic 3 Videos

This video introduces how organisms are named using the binomial naming system and explains the rules that govern scientific names. It also explores what defines a species, the limitations of the biological species concept, and how new species arise through speciation.

This video reviews chromosome structure in prokaryotes and eukaryotes and explains how chromosome number helps distinguish species. It then introduces karyotyping, chromosomal conditions, and the evidence supporting the fusion origin of human chromosome 2.

This video explains what a genome is and how genome size and base pair number help differentiate species. It also explores genome sequencing through the Human Genome Project, including its current use in evolutionary biology and future role in personalised medicine.

This video revisits the biological species concept at higher level, including its limitations in asexual organisms and horizontal gene transfer. It introduces dichotomous keys and DNA barcoding as modern methods for identifying and distinguishing species.

This video explains the hierarchical system of classification from domain to species and distinguishes between artificial and natural classification. It also explores the development of modern classification systems, including Woese’s three-domain model.

This video introduces cladistics as a method of classifying organisms based on evolutionary relationships. It explains how cladograms are constructed using morphology or DNA data and outlines the principles of parsimony and molecular clocks.

This video covers the principles of gas exchange and the key features of efficient gas exchange surfaces. It focuses on mammalian lungs, including alveolar structure and adaptations that maximise oxygen and carbon dioxide diffusion.

This video explains how ventilation occurs through inhalation and exhalation using antagonistic muscles. It also introduces spirometry, spirographs, and how lung volumes change during exercise.

This video explores gas exchange in plants by examining leaf structure and the role of stomata and guard cells. It also explains transpiration, the factors affecting its rate, and methods used to measure transpiration experimentally.

This video explores the structure and function of haemoglobin, foetal haemoglobin, and myoglobin. It explains cooperative binding, the Bohr shift, and how oxygen dissociation curves change under different physiological conditions.

This video introduces the structure and function of the human cardiovascular system, including arteries, veins, and capillaries. It also explains how coronary heart disease develops and outlines key risk factors linked to heart attacks.

This video examines transport in plants by focusing on stem and root structure and vascular bundles. It explains xylem adaptations and how the transpiration stream moves water through plants using pressure gradients, cohesion, and adhesion.

This video examines tissue fluid formation at capillary beds and explains how hydrostatic and osmotic pressures drive exchange. It also introduces the lymphatic system and its role in fluid balance and immune transport.

This video compares single and double circulatory systems and explains why mammals require double circulation. It also reviews heart structure and adaptations that enable efficient, one-way blood flow.

This video explains the electrical control of the heart and the sequence of events in the cardiac cycle. It links pressure changes to valve movement and outlines the pathway of blood flow through the heart and body.

This video explores root pressure as a mechanism supporting water movement in plants and introduces mycorrhizal associations. It also explains phloem structure and the mass flow mechanism that drives translocation from source to sink.

This video introduces locomotion as a key survival process and distinguishes between sessile and motile organisms. It then explores aquatic locomotion, highlighting swimming and diving adaptations in marine mammals.

This video examines the structure of skeletal muscle, focusing on sarcomeres and the proteins involved in contraction. It also explains motor units and how neurons coordinate muscle fibre activation.

This video explains the sliding filament mechanism of muscle contraction and the role of calcium, ATP, and cross-bridge cycling. It also explores antagonistic muscle pairs and how they coordinate opposing movements.

This video explores how bones and joints enable movement through lever systems and synovial joint structure. It also explains joint range of motion and methods used to measure joint angles.

This video introduces the hierarchical organisation of living systems from cells to whole organisms. It also explains how body systems are integrated through nervous and endocrine signalling to maintain coordination and homeostasis.

This video explores the structure and functions of the central nervous system, including the brain and spinal cord. It also introduces the autonomic and enteric nervous systems and explains how they regulate involuntary processes such as digestion and heart rate.

This video explains how the peripheral nervous system transmits information between the body and the CNS using sensory and motor neurons. It also examines nerve structure and shows how reflex arcs produce rapid, protective responses.

This video focuses on the roles of the cerebellum and medulla oblongata in coordinating movement and regulating vital involuntary functions. It explains how heart rate and ventilation are controlled through sensory input and feedback mechanisms.

This video explains how the endocrine system uses hormones to produce long-lasting, body-wide responses. It explores sleep regulation through melatonin and the fight-or-flight response mediated by adrenaline.

This video explains indeterminate plant growth and the role of meristems and phytohormones in regulating development. It also outlines micropropagation and how auxin–cytokinin balance controls root and shoot formation.

This video explores phototropism and how auxin redistribution causes directional growth in response to light. It also explains fruit ripening as a positive feedback process driven by ethylene.

This video introduces the immune system and its components, including the primary and secondary defence. It then covers the primary defence in more depth, and concludes by covering the mechanism of clotting.

This video covers the foundational concept of antigen recognition in the secondary defence system, and how this differs per cell types. It then reinforces this point by delving into blood transfusions and how these relate to immune responses.

This video completes the content of the immune system by covering the innate and adaptive immune responses in detail, including phagocytes, T cells, B cells, and antibodies. It finishes by introducing the concept of the secondary immune response.

This video begins by introducing the spread of HIV and its mechanism of action. It then moves on to discuss how antibiotics work, why antibiotic resistance is a problem, and the strategies we use to mitigate it.

This video explains the concept of zoonotic diseases and why they are challenging. It then explains why vaccines are a useful strategy, and discusses what happened during COVID-19. It concludes by introducing statistical calculations of COVID-19 data.

This video recaps the types of reproduction, and then delves into sexual reproduction, including the sources of genetic variation, gametes, and reproductive strategies. It finished by covering the male and female reproductive anatomies.

This video delves into the details of the menstrual cycle, including the basic mechanisms of the follicular and luteal phases, and the hormones involved. It summarises the information by discussing the menstrual cycle graph in detail.

This video goes into depth on the mechanism of fertilization in sexual reproduction, and what the advantages of this process are. It then covers the process of in-vitro fertilization (IVF) in women who struggle to conceive naturally.

This video introduces plant reproduction by covering the reproductive anatomy of flowering plants. It then delves into the concept of cross-pollination, self-pollination, and mechanisms to prevent self-pollination.

This video examines plant reproduction in detail, including the processes of pollination, fertilization, and seed dispersion. It then continues with the beginning of plant life by discussing seed anatomy, and the process of germination.

This video examines spermatogenesis and oogenesis, highlighting key hormonal control and meiotic differences. It also reviews fertilization and the mechanisms that prevent polyspermy.

This video follows development from zygote to embryo, implantation, and early placental formation. It also explains how pregnancy tests detect hCG using antibody-based assays.

This video explores placental structure and function, focusing on exchange between maternal and foetal blood. It then explains the hormonal positive feedback loop involving oxytocin that drives labour and birth.

This video explains the hormonal cascade controlling puberty and the development of secondary sexual characteristics. It also examines menopause, hormone replacement therapy, and the importance of distinguishing correlation from causation in medical research.

This video introduces alleles as different versions of the same gene and explains how dominance, co-dominance, and incomplete dominance affect phenotype. It uses ABO blood groups and Mirabilis jalapa flowers to illustrate key inheritance patterns.

This video explains how Punnett grids are used to predict inheritance and explores Mendel’s pea plant experiments and laws of inheritance. It also introduces phenotypic plasticity, showing how environmental factors can influence phenotype without changing genotype.

This video examines monogenic genetic diseases, including phenylketonuria and sex-linked conditions such as haemophilia. It also explains how pedigree charts are used to identify inheritance patterns across generations.

This video explores genetic variation, distinguishing between discrete and continuous variation and introducing polygenic traits. It also teaches how to interpret box and whisker plots to analyse biological data and identify outliers.

This video introduces dihybrid inheritance and explains the difference between unlinked and linked genes. It explores independent and dependent assortment, the effects of crossing over, and how inheritance ratios change when genes are linked.

This video explains how the chi-squared test is used to determine whether genes are linked or assort independently. It walks through the calculation process and shows how to interpret statistical significance in dihybrid crosses.

This video explains how basic homeostatic responses work via negative feedback. It then delves into the depths of glucose regulation via the role of the pancreas, mechanisms of insulin & glucagon, and the differences between Type 1 and Type 2 diabetes.

This video explores how the body maintains a stable internal temperature using hormonal and nervous responses and thyroxin. It then delves into the body responses to cold and heat to complete the picture of thermoregulation.

This video introduces osmoregulation and distinguishes it from excretion. It examines kidney structure and nephron anatomy, outlining how filtration and selective reabsorption maintain water and solute balance.

This video explains ultrafiltration, selective reabsorption, and the role of the loop of Henlé and ADH in regulating water balance. It also explores how blood flow is redistributed during different activity levels to maintain homeostasis.