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

12. Meiosis

Genetic Variation During Meiosis

General Biology

12. Meiosis

Genetic Variation During Meiosis

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Multiple Choice

Where are populations with high frequencies of the sickle-cell trait most commonly found?

In populations living near the Arctic Circle

In areas with high altitudes, such as the Andes mountains

In northern European countries with cold climates

In regions where malaria is or was historically prevalent, such as sub-Saharan Africa

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Verified step by step guidance

Understand the sickle-cell trait: The sickle-cell trait is a genetic condition caused by a mutation in the hemoglobin gene. Individuals with one copy of the sickle-cell allele (heterozygous) have some resistance to malaria, a disease caused by Plasmodium parasites transmitted by mosquitoes.

Recognize the relationship between malaria and the sickle-cell trait: The sickle-cell trait provides a selective advantage in regions where malaria is prevalent. This is because the altered hemoglobin in individuals with the trait makes it harder for the malaria parasite to survive and reproduce within red blood cells.

Identify regions with high malaria prevalence: Malaria is most common in tropical and subtropical regions, particularly sub-Saharan Africa, parts of South Asia, and some areas of Central and South America. Historically, these regions have had high rates of malaria transmission.

Connect the sickle-cell trait to population genetics: Over generations, natural selection has increased the frequency of the sickle-cell allele in populations living in areas with high malaria prevalence. This is an example of balanced polymorphism, where the heterozygous condition provides a survival advantage.

Conclude that populations with high frequencies of the sickle-cell trait are found in regions where malaria is or was historically prevalent, such as sub-Saharan Africa, rather than areas with cold climates or high altitudes.