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

26. Prokaryotes

Prokaryotic Metabolism

General Biology

26. Prokaryotes

Prokaryotic Metabolism

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2:52 minutes

Problem 9

Textbook Question

Streptococcus mutans obtains energy by oxidizing sucrose. This bacterium is abundant in the mouths of Western European and North American children and is a prominent cause of cavities. The organism is virtually absent in children from East Africa, where tooth decay is rare. Propose a hypothesis to explain this observation. Outline the design of a study that would test your hypothesis.

Verified step by step guidance

Identify the key variables involved in the hypothesis: the presence of Streptococcus mutans, the consumption of sucrose, and the prevalence of tooth decay in different geographical regions.

Formulate a hypothesis based on the observation. For example, you might hypothesize that the lower prevalence of Streptococcus mutans in East African children is due to dietary differences, specifically lower consumption of sucrose, which in turn leads to less tooth decay.

Design a study to test the hypothesis. Consider a comparative study that examines the diets of children from Western Europe, North America, and East Africa, focusing on sucrose intake. Additionally, measure the prevalence of Streptococcus mutans in the mouths of children from these regions.

Include control variables in your study design to isolate the effect of sucrose consumption on the presence of Streptococcus mutans and the incidence of tooth decay. Control variables might include age, general dental hygiene practices, and access to dental care.

Outline how you will collect and analyze the data. This might involve dental examinations to assess tooth decay, microbiological swabs to detect Streptococcus mutans, and dietary surveys to estimate sucrose consumption. Statistical analysis can then be used to determine if there is a significant correlation between sucrose consumption, the presence of Streptococcus mutans, and the incidence of tooth decay.

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Key Concepts

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

Role of Streptococcus mutans in Dental Caries

Streptococcus mutans is a type of bacteria that plays a significant role in the development of dental caries (cavities). It metabolizes sugars, particularly sucrose, producing acids that demineralize tooth enamel. Understanding its metabolic pathways and how it thrives in certain environments is crucial for explaining its prevalence in specific populations.

Impact of Diet on Oral Microbiome

The oral microbiome is influenced by dietary habits, which can vary significantly between populations. Diets high in sugars and carbohydrates promote the growth of cariogenic bacteria like S. mutans, while diets low in these substances may support a healthier oral microbiome. This concept is essential for hypothesizing why children in East Africa, who may consume less sugar, have lower rates of tooth decay.

Hypothesis Testing and Study Design

Hypothesis testing involves formulating a testable statement based on observations, followed by designing a study to collect data that supports or refutes the hypothesis. A well-structured study might include comparing the diets and oral health of children from different regions, using methods such as surveys and microbiological analysis to assess the presence of S. mutans and dietary intake.

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