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

30. Overview of Animals

Overview of Animals

General Biology

30. Overview of Animals

Overview of Animals

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2:25 minutes

Problem 3

Textbook Question

Which of the following was probably an important factor in bringing about the Cambrian explosion?
a. The movement of animals onto land
b. An increase in the concentration of atmospheric nitrogen
c. The emergence of predator-prey relationships
d. The origin of bilaterian animals

Verified step by step guidance

Understand the Cambrian explosion: It was a period approximately 541 million years ago when there was a rapid diversification of multicellular organisms, leading to the appearance of most major animal phyla.

Consider the options: (A) movement of animals onto land, (B) increase in atmospheric nitrogen, (C) emergence of predator-prey relationships, (D) origin of bilaterian animals.

Evaluate option (A): The movement of animals onto land occurred much later than the Cambrian explosion, so it is unlikely to be a contributing factor.

Evaluate option (B): While atmospheric changes can influence evolution, nitrogen is not directly linked to the diversification seen in the Cambrian explosion.

Evaluate options (C) and (D): The emergence of predator-prey relationships (C) could drive evolutionary changes due to natural selection pressures, and the origin of bilaterian animals (D) represents a significant evolutionary development that could lead to diversification.

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Key Concepts

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

Cambrian Explosion

The Cambrian Explosion refers to a period approximately 541 million years ago when there was a rapid diversification of life forms on Earth. This event is marked by the sudden appearance of most major animal phyla in the fossil record. It is significant because it represents a major evolutionary milestone, leading to the complex ecosystems we see today.

Predator-Prey Relationships

Predator-prey relationships involve interactions where one organism (the predator) hunts and consumes another organism (the prey). These interactions can drive evolutionary changes, as prey species develop adaptations to avoid predation, and predators evolve strategies to catch prey. Such dynamics can lead to increased biodiversity and complexity in ecosystems, potentially contributing to events like the Cambrian Explosion.

Bilaterian Animals

Bilaterian animals are organisms with bilateral symmetry, meaning they have a distinct front and back, as well as a top and bottom. This body plan allows for more complex structures and functions, such as a centralized nervous system. The emergence of bilaterians is considered a key evolutionary development, as it enabled greater mobility and diversity, which may have played a role in the Cambrian Explosion.