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

6. The Membrane

Biological Membranes

General Biology

6. The Membrane

Biological Membranes

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Multiple Choice

Why are cell membranes composed primarily of hydrophobic molecules?

Cell membranes must be composed of polar molecules in order to interact with the aqueous solutions inside cells.

In order to maintain a proper pH, cell membranes must be hydrophobic.

Cell membranes must be hydrophobic in order to allow polar and charged molecules to enter and leave the cell.

In order to perform their function of separating the aqueous solutions outside cells from the aqueous solutions inside cells, cell membranes cannot be soluble in water.

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Verified step by step guidance

Understand the structure of cell membranes: Cell membranes are primarily composed of a lipid bilayer, which consists of phospholipids. Each phospholipid molecule has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails.

Recognize the role of hydrophobic molecules: The hydrophobic tails of phospholipids face inward, away from water, while the hydrophilic heads face outward towards the aqueous environment. This arrangement creates a barrier that separates the inside of the cell from the outside environment.

Consider the function of the cell membrane: The cell membrane's primary function is to act as a selective barrier, controlling the movement of substances in and out of the cell. The hydrophobic core of the membrane prevents the free passage of polar and charged molecules, which are typically soluble in water.

Evaluate the importance of the hydrophobic nature: The hydrophobic nature of the cell membrane is crucial for maintaining the integrity of the cell, preventing the dissolution of the membrane in the aqueous environment, and ensuring that the cell can maintain its internal conditions.

Conclude with the correct reasoning: The cell membrane must be hydrophobic to effectively separate the aqueous solutions inside the cell from those outside, ensuring that the membrane itself is not soluble in water and can perform its function as a barrier.