Course review
Review each learning objective in this topic, then open its concept explanation or question set.
Learning objective
• A zygote divides to produce unspecialized cells that later differentiate • Differentiation occurs when different genes are activated in different cells • Morphogen gradients control gene expression and body pattern formation
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Stem cells self-renew by repeated division while remaining undifferentiated • Stem cells have potency: the capacity to differentiate into mature cell types • Embryonic stem cells have broader potential than most adult stem cells
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Stem cell niches provide signals that maintain, activate, or differentiate stem cells • Bone marrow niches regulate haematopoietic stem cells that form blood cells • Hair follicle bulge niches contain multipotent stem cells for hair regeneration
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Totipotent cells can form all body cells plus placental cells • Pluripotent cells form all body cell types but not placenta or totipotent cells • Multipotent adult stem cells repair and maintain limited tissues or organs
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Specialized cells vary widely in size according to function • Egg cells are large for nutrient storage; sperm are small with a long flagellum • Neurons can be very long, and striated muscle fibres are extended multinucleate cells
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Surface area controls exchange, while volume controls metabolic demand • As cells grow, volume increases faster than surface area • Low surface area-to-volume ratio limits diffusion and therefore cell size
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Erythrocytes are flattened, biconcave, flexible, and lack a nucleus for oxygen exchange • Proximal convoluted tubule cells have apical microvilli and basal invaginations • Mitochondria in PCT cells support active transport during reabsorption
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Type I pneumocytes are flattened and thin to minimize diffusion distance • Tight connections reduce leakage of tissue fluid into alveoli • Type II pneumocytes are cuboidal, contain lamellar bodies, and secrete surfactant
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Cardiac muscle is branched, myogenic, striated, and joined by intercalated discs • Intercalated discs contain gap junctions for synchronized heart contraction • Skeletal muscle fibres are long, multinucleate, striated, and packed with myofibrils and mitochondria
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Sperm have a haploid nucleus, acrosome, mitochondria-rich middle piece, and flagellum • The acrosome digests the zona pellucida and the flagellum enables motility • Secondary oocytes have nutrient-rich cytoplasm, zona pellucida, cortical granules, and follicle cells
Start with the concept explanation, then practise to create mastery evidence.