Bio Exam 5

What types of animals are osmoconformers, both generally and specifically (e.g. examples)? What is the osmolarity of their tissues relative to their environment?

All osmoconformers are marine animals (examples: jellyfish, sea urchins, octopi). Relative to seawater, their tissues are isoosmotic.

Why do animals produce ammonia? Why is ammonia toxic?

Ammonia is very toxic in part because its ion, ammonium (NH4+) interferes with the oxidative phosphorylation stage of cellular respiration.

What types of animals are terrestrial osmoregulators, both generally and specifically (e.g. examples)? What is the osmolarity of their tissues relative to their environment? What types of mechanisms must they use to maintain osmoregulatory homeostasis? What specific adaptations do they have that allow them to maintain homeostasis?

Examples: dogs, birds. Terrestrial animals must continually take in water to counteract water loss, and/or use mechanisms to conserve water internally. Water loss via urine/feces, sweat, breathing or panting/water gain via ingestion and metabolism (cellular respiration). Electrolyte loss via urine/electrolyte gain via ingestion. Body coverings (shells of snails) that prevent dehydration, and behavioral modifications (insects close tracheal openings).

Define excretion. What is the connection between osmoregulation and excretion?

Excretion is the process that rids the body of nitrogenous metabolites and other metabolic waste products.

What types of animals are freshwater osmoregulators, both generally and specifically (e.g. examples)? What is the osmolarity of their tissues relative to their environment? What types of mechanisms must they use to maintain osmoregulatory homeostasis? What specific adaptations do they have that allow them to maintain homeostasis?

Frogs, freshwater fish with tissues hyperosmotic relative to the surrounding water (the solution inside the body must contain more solutes than the solution outside). Freshwater osmoregulators solve the problem of water balance by drinking very little water and excreting large amounts of very dilute urine. Freshwater osmoregulators must also continually take in solutes because they cannot tolerate solute levels as low as freshwater. To increase salt intake, freshwater fish typically use their gills.

Distinguish between isoosmotic, hyperosmotic, and hypoosmotic solutions in terms of solute and water concentration. What is the direction of osmosis between two isoosmotic solutions? between a hyperosmotic solution and a hypoosmotic solution?

Isoosmotic solutions are solutions with equal concentrations of solutes (no net movement of water). A hyperosmotic (higher solute, lower water) solution has a higher solute concentration than a hypoosmotic solution -- water will move by osmosis from a hypoosmotic solution to a hyperosmotic one.

What types of animals are marine osmoregulators, both generally and specifically (e.g. examples)? What is the osmolarity of their tissues relative to their environment? What types of mechanisms must they use to maintain osmoregulatory homeostasis? What specific adaptations do they have that allow them to maintain homeostasis? Answers these questions for both freshwater osmoregulators and terrestrial osmoregulators as well.

Marine vertebrates such as whales, dolphins, marine fish, and turtles. Their tissues are hypoosmotic relative to salt water (the solution inside the body must contain fewer solutes than the solution outside). Marine osmoregulators must continually take in (drink) water to counteract water loss and lose little water in the urine (produce small amounts of concentrated urine). Marine osmoregulators must also continually discard excess solutes; to rid the body of the excess salts taken in, marine fish typically use both their gills and kidneys.

Distinguish between the three different types of nitrogenous waste animals excrete. What types of animals excrete each type? What are the major advantages and disadvantages associated with processing and excreting each type of waste? What factors are typically correlated with the type of waste production found in animal species?

Most terrestrial animals and many marine osmoregulators do not have access to enough water to dilute and excrete toxic ammonia, instead producing urea. Urea is soluble in water. The main advantage of producing urea is its low toxicity - animals can transport urea in the circulatory system, and store it safely at fairly high concentrations, which helps to prevent water loss, disadvantage is energy cost.

Distinguish between an osmoconformer and osmoregulator.

Osmoconformer, i.e. be isoosmotic with the surrounding environment. Osmoregulator, i.e. control the internal osmolarity independent of the surrounding environment.

What is osmoregulation and why is it necessary? What role/s do electrolytes play in osmoregulation?

Osmoregulation is the process by which animals control solute concentrations and balance water gain and loss. Cells require precise concentrations of electrolytes to function normally.

What types of osmoregulatory adaptations do you find in migrating fish?

Salmon, sea bass and other fish that migrate between freshwater and seawater undergo dramatic physiological (hormonal) changes that affect their osmoregulatory capabilities. When they migrate to the ocean: Discard solutes from their body with chloride cells Produce small amounts of urine to decrease water loss When in rivers and streams: Bring solutes into their body with chloride cells Produce large amounts of dilute urine.

Define osmolarity.

The total solute concentration of a solution, measured as moles of solute per liter of solution.