Presentation on theme: "2.D: Growth and dynamic homeostasis are influenced by changes in the environment."— Presentation transcript:
2.D: Growth and dynamic homeostasis are influenced by changes in the environment
Organisms Respond to External Events I.e. taxis or kinesis – Many animals change speed based on light (pillbugs run wild when exposed to light) – Many animals change direction in response to stimuli (sharks swim towards blood) Plants grow towards light (phototropism)
Biotic vs. Abiotic Factors Biotic = Living Animals Plants Fungi Bacteria/ Archaeans Abiotic = Non-living Sunlight Water Vitamins/ Minerals/ Nutrients Temperature
Cells Are Affected by Both Biotic/Abiotic Factors i.e. bacterial cells attach to each other to form biofilms Cells shrink/grow depending on water availability Cells stop growing after a certain density (except in the case of cancers)
Organisms Interact with Biotic/Abiotic Factors Organisms access to nutrients is affected by other factors i.e. symbiosis, predator-prey, nutrient availability etc
Symbiosis-Two species living together Mutualism-both benefit Commensalism- one benefits, other unaffected Parasitism- one benefits at other’s expense "live microbial feed supplement which beneficially affects the host animal by improving its intestinal microbial balance".
Abiotic Effects on Growth Better nutrition Taller individuals More sunlight More plant growth
Evolution of Homeostatic Mechanisms Some mechanisms are conserved- showing common ancestry Others have changed, demonstrating divergent evolution
i.e. nitrogenous waste removal All animals produce nitrogen byproducts Animals in different environments have evolved different mechanisms for excreting these wastes
Ammonia Toxic byproduct of protein degradation In dilute concentrations is no big deal, so aquatic organisms can excrete it into water
Urea Mammals convert ammonia into urea Urea travels through the blood to the kidneys and is excreted with water and other substances as urine
Solid Uric Acid In birds and reptiles (and some desert mammals) nitrogen waste is excreted as a solid Prevents water loss and buildup of water wastes in the shell of an egg
Evolution of Circulatory System Shows Common Ancestry and Divergence
Your consent to our cookies if you continue to use this website.