Problem 3 - Biology: The Dynamic Science

Question

Products of metabolism in humans, as in: a. terrestrial amphibians, can include urea, which requires more energy to produce than ammonia. b. birds and reptiles, can include uric acid, which is nontoxic and excreted as a paste. c. sharks, are primarily excreted as ammonia. d. hydra, must be isoosmotic with the water ingested. e. other mammals, cannot be water as water comes only from what they drink.

Step-by-Step Solution

Answer

The different organisms all have different strategies to excrete the metabolic waste. Urea, requiring more energy to produce, is excreted by amphibians. Birds and reptiles excrete non-toxic uric acid as a paste, which requires less water. Sharks excrete ammonia which becomes less toxic in their water environment. Hydra must maintain an isoosmotic balance with the water they're in. Other mammals don't secrete waste as water but regulate water meticulously to maintain internal homeostasis.

Step 1: Understand Urea Production in Terrestrial Amphibians

Terrestrial amphibians produce urea as a metabolic product. Producing urea requires more energy than producing ammonia, but it has the advantage of being less toxic. Thus, this enables these amphibians to survive in their environment without causing self-harm.

Step 2: Examine Uric Acid Production in Birds and Reptiles

Birds and reptiles excrete their metabolic waste in the form of uric acid, which is non-toxic and can be excreted as a paste. This reduces their need for water to dilute it, which is advantageous in dry environments.

Step 3: Discuss Ammonia Excretion in Sharks

Sharks primarily excrete ammonia. Because they live in a water environment, the toxicity of ammonia can be handled as it is diluted.

Step 4: Hydra's Isoosmotic Metabolism

Hydra, an aquatic organism, have a metabolism where metabolic waste must remain isoosmotic, or of equal solute concentration, with the water ingested. This helps to maintain a balance internally despite their simple body structure.

Step 5: Mammalian Metabolic Waste

Mammals, including humans, cannot excrete metabolic wastes simply as water. Water output from lungs, skin and excretory system is regulated meticulously to maintain internal homeostasis. The water they take in primarily comes from what they drink.