What you’ll learn 8 learning objectives Choose one objective for a focused lesson, or study the complete topic.
96 min Start full topic B4.1.1 Habitat definition • Habitat is the place where an organism, population, species, or community lives • Habitat descriptions can include geographic location, physical position, and ecosystem type • Microhabitats are small areas with conditions different from the surrounding habitat LOW frequency · 1 paper 10 min View concept B4.1.2 Adaptations to abiotic environment • Adaptations improve survival under abiotic conditions such as water availability, salinity, oxygen, and wind • Marram grass has rolled, hairy leaves and thick cuticle to reduce water loss in dunes • Mangroves use aerial roots, pneumatophores, salt exclusion, or salt excretion in saline low-oxygen swamps LOW frequency · 3 papers 15 min View concept B4.1.3 Abiotic variables affecting distribution • Species distribution depends on abiotic variables such as temperature, salinity, pH, light, rainfall, humidity, and substratum • Limiting factors can restrict survival, growth, reproduction, or activity by deficiency or excess • Plant limiting factors include light, water, nutrients, carbon dioxide, and temperature LOW frequency · 13 papers 14 min View concept B4.1.4 Range of tolerance of limiting factor • A range of tolerance lies between critical minimum and maximum limits • The optimum zone supports highest survival, growth, abundance, and reproduction • Zones of stress and intolerance explain reduced abundance or absence along environmental gradients LOW frequency · 7 papers 13 min View concept B4.1.5 Coral reef formation conditions • Coral reefs need warm, shallow, clear, sunlit, saline water with suitable pH • Reef-building corals rely on photosynthetic symbiotic algae • Low nutrients, sediment, cold water, or reduced light can limit reef formation LOW frequency · 1 paper 10 min View concept B4.1.6 Terrestrial biome distribution • Terrestrial biome distribution is mainly determined by temperature, rainfall, and insolation • Productivity depends strongly on water availability and photosynthesis rate • Latitude and seasonal variation help explain rainforest, temperate forest, taiga, grassland, tundra, and desert distribution LOW frequency · 7 papers 12 min View concept B4.1.7 Biomes • Biomes are groups of ecosystems with similar communities due to similar abiotic conditions • Similar biomes can evolve similar forms through convergent evolution • Examples include tropical rainforest, temperate forest, taiga, grassland, tundra, and hot desert LOW frequency · 3 papers 11 min View concept B4.1.8 Adaptations to hot deserts and tropical rainforest • Hot desert strategies include expire, evade, or endure under heat and water scarcity • Camels, cacti, scorpions, and kangaroo rats show water-saving, heat-avoidance, or storage adaptations • Tropical rainforest adaptations include pitcher plant nutrient capture, gibbon brachiation, flying lizard gliding, and orchid mantis mimicry LOW frequency · 2 papers 11 min View concept
