|
|
The familiar sounds of your heart are made by the heart's valves as they open and close.
In most climates, 8 to 10 glasses of water per day is recommended for adults. The best indicator for adequate fluid intake is frequent, clear urination.
People often find it difficult to accept the idea that bacteria can be beneficial and improve health. Lactic acid bacteria are good, and when eaten, these bacteria improve health and increase longevity. These bacteria included in foods such as yogurt.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
![H. erectus migrated out of Africa beginning about 1.8 million years ago and is first known from Geor](https://biology-forums.com/gallery/47/medium_275510_22_02_15_5_56_58_207731480.jpeg)
![Midway Island, an inhospitable atoll acquired in 1867, was valuable as a military base located midwa](https://biology-forums.com/gallery/47/medium_6_02_03_16_7_45_21_234011450.jpeg)