Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

42. Osmoregulation and Excretion

Osmoregulation and Excretion

General Biology

42. Osmoregulation and Excretion

Osmoregulation and Excretion

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1:01 minutes

Problem 6

Textbook Question

African lungfish, which are often found in small stagnant pools of fresh water, produce urea as a nitrogenous waste. What is the advantage of this adaptation?
a. Urea takes less energy to synthesize than ammonia.
b. Small stagnant pools do not provide enough water to dilute ammonia, which is toxic.
c. Urea forms an insoluble precipitate.
d. Urea makes lungfish tissue hypoosmotic to the pool.

Verified step by step guidance

Understand the context: African lungfish live in small stagnant pools of fresh water, which can have limited water availability and may not be able to dilute waste products effectively.

Identify the problem with ammonia: Ammonia is a common nitrogenous waste in aquatic animals, but it is highly toxic and requires a lot of water to be safely excreted.

Consider the properties of urea: Urea is less toxic than ammonia and can be excreted with less water, making it a more suitable waste product in environments where water is scarce.

Evaluate the options: Option b suggests that small stagnant pools do not provide enough water to dilute ammonia, which aligns with the need for a less toxic waste product like urea.

Conclude the advantage: The adaptation of producing urea allows lungfish to survive in environments with limited water by reducing the toxicity of their nitrogenous waste, supporting option b.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nitrogenous Waste Products

Nitrogenous waste products are byproducts of protein metabolism that need to be excreted from the body. The primary forms are ammonia, urea, and uric acid. Ammonia is highly toxic and requires a lot of water to be safely excreted, while urea is less toxic and can be excreted with less water, making it advantageous in water-limited environments.

Ammonia Toxicity

Ammonia is a nitrogenous waste that is highly toxic to organisms. It requires a large amount of water to be diluted to non-toxic levels, which is why aquatic animals in water-rich environments can excrete it directly. In contrast, animals in environments with limited water, like the African lungfish, need to convert ammonia into less toxic substances like urea.

Adaptation to Stagnant Water Environments

Adaptations to stagnant water environments involve physiological changes that allow organisms to survive in conditions with limited water flow and oxygen. For the African lungfish, producing urea instead of ammonia is an adaptation that reduces water dependency for excretion, allowing survival in small, stagnant pools where water is scarce and ammonia cannot be easily diluted.

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