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

25. Phylogeny

Cladistics

General Biology

25. Phylogeny

Cladistics

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Multiple Choice

Traditionally, scientists have identified 4 Kingdoms in the domain Eukaryota: the animals, the plants, the fungi, and the protists. Some scientists argue that the protists actually represent multiple kingdoms, and that there should be many more kingdoms in the domain Eukaryota. Based on the tree, why do some scientists argue for so many kingdoms?

Protists represent a polyphyletic group, so they should not be grouped together.

Protists are a paraphyletic group and modern systematics is usually based on monophyletic groups.

Some protists are more closely related to the archaea and bacteria making them a polyphyletic group.

Protists are a monophyletic group but do not represent a true clade according to modern classification.

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Verified step by step guidance

Examine the phylogenetic tree provided in the image. Notice that the tree is divided into different branches representing various groups within the domain Eukaryota.

Identify the groups labeled as 'Protists' in the tree. These groups are marked with red lines and include Amoebozoa, Excavata, Glaucocystophytes algae, Red algae-Rhodophytes, Green algae-Chlorophytes, Green algae-Charophytes, and SAR.

Observe that the protists do not form a single, cohesive group on the tree. Instead, they are spread across different branches, indicating that they do not share a common ancestor exclusive to them, which is a characteristic of a polyphyletic group.

Understand that a polyphyletic group consists of organisms that are grouped together based on similar characteristics but do not share a recent common ancestor. This is why some scientists argue that protists should not be grouped together as a single kingdom.

Recognize that modern systematics often prefers classification based on monophyletic groups, which include all descendants of a common ancestor. Since protists are spread across different branches and do not form a monophyletic group, scientists propose dividing them into multiple kingdoms to better reflect their evolutionary relationships.