9.2: Osmoregulation and Excretion

Question 1

What is osmoregulation, and how is it related to osmosis? ``````

Answer 1

1. Osmoregulation:
   ○ The process by which animals maintain a balance of water and solutes in their bodies to ensure homeostasis.
   
   2. Osmosis:
      ○ The passive movement of water across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.
   3. Relationship:
      ○ Osmoregulation controls water movement (via osmosis) to prevent dehydration or overhydration.

Question 2

Compare and contrast osmoconformers and osmoregulators.

Answer 2

1. Osmoconformers:
   ○ Match their internal osmolarity to the surrounding environment.
   ○ Typically marine animals (e.g., jellyfish, sharks).
   ○ Energy-efficient but dependent on stable external conditions.
   
   2. Osmoregulators:
      ○ Maintain a constant internal osmolarity regardless of the environment.
      ○ Found in both freshwater and terrestrial animals (e.g., fish, mammals).
      ○ Requires significant energy expenditure.

Question 3

What are the different nitrogenous waste products, and how are they related to the animal’s

Answer 3

1. Ammonia:
   ○ Highly toxic; requires large amounts of water for excretion.
   ○ Common in aquatic animals (e.g., fish).
   
   2. Urea:
      ○ Less toxic; requires moderate water for excretion.
      ○ Found in mammals, amphibians, and cartilaginous fish.
   3. Uric Acid:
      ○ Least toxic; excreted as a paste to conserve water.
      ○ Found in birds, reptiles, and insects.
   4. Relation to Environment:
      ○ Water availability dictates the type of nitrogenous waste excreted.

Question 4

What are the four main types of excretory systems in animals?

Answer 4

1. Protonephridia:
   ○ Found in flatworms.
   ○ Use flame cells to filter and excrete waste.
   
   2. Metanephridia:
      ○ Found in annelids (e.g., earthworms).
      ○ Tubules collect and excrete waste from the coelom.
   3. Malpighian Tubules:
      ○ Found in insects.
      ○ Remove waste from hemolymph and excrete it into the digestive tract.
   4. Kidneys:
      ○ Found in vertebrates.
      ○ Filter blood and excrete waste as urine.
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