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

13. Mendelian Genetics

Non-Mendelian Genetics

General Biology

13. Mendelian Genetics

Non-Mendelian Genetics

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Multiple Choice

In people with sickle-cell disease, red blood cells break down, clump, and clog the blood vessels. The blood vessels and the broken cells accumulate in the spleen. These events lead to physical weakness, heart failure, joint pain, and brain damage. Such a suite of symptoms can be explained by __________.

the polygenic nature of sickle-cell disease

an epistatic interaction between the sickle-cell allele and a proteolytic enzyme gene

a bacterial infection interacting with the sickle-cell allele

side effects of the drugs used to cure sickle-cell disease

the pleiotropic effects of the sickle-cell allele

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Verified step by step guidance

Understand the concept of pleiotropy: Pleiotropy occurs when one gene influences multiple phenotypic traits. In the case of sickle-cell disease, the sickle-cell allele affects various systems in the body, leading to multiple symptoms.

Identify the symptoms associated with sickle-cell disease: These include physical weakness, heart failure, joint pain, and brain damage, all of which are linked to the sickle-cell allele.

Recognize that the symptoms are not caused by multiple genes (polygenic) or interactions with other genes (epistasis), but rather by the single sickle-cell allele affecting multiple traits.

Consider the other options: A bacterial infection or side effects of drugs would not explain the inherent genetic cause of the symptoms.

Conclude that the suite of symptoms is best explained by the pleiotropic effects of the sickle-cell allele, as it directly causes the diverse range of symptoms observed in individuals with the disease.