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

5. Cell Components

Prokaryotic & Eukaryotic Cells

General Biology

5. Cell Components

Prokaryotic & Eukaryotic Cells

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Multiple Choice

Which of the following is a key difference between whales and fish?

Whales use gills for respiration, while fish use lungs.

Whales are mammals and breathe air using lungs, while fish are not mammals and use gills to extract oxygen from water.

Whales have scales covering their bodies, while fish have smooth skin.

Whales lay eggs in water, while fish give birth to live young.

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Verified step by step guidance

Step 1: Begin by identifying the key biological classification of whales and fish. Whales are mammals, which means they share characteristics such as breathing air using lungs, giving live birth, and having hair at some stage of their life cycle. Fish, on the other hand, are not mammals; they are aquatic vertebrates that use gills to extract oxygen from water and typically lay eggs.

Step 2: Examine the respiratory systems of whales and fish. Whales, as mammals, have lungs and must surface to breathe air. Fish, however, have gills that allow them to extract dissolved oxygen directly from water, making their respiratory systems fundamentally different.

Step 3: Consider the reproductive methods of whales and fish. Whales give birth to live young, a characteristic of mammals, while most fish lay eggs in water, which is typical of their reproductive strategy.

Step 4: Analyze the external body coverings of whales and fish. Whales have smooth skin and may have a layer of hair during certain stages of development, while fish are covered in scales, which serve as protection and aid in movement through water.

Step 5: Summarize the key differences based on the observations above: Whales are mammals that breathe air using lungs, give live birth, and have smooth skin, while fish are not mammals, use gills for respiration, lay eggs, and have scales covering their bodies.