Let’s get it started! What property of water molecules explains adhesion and cohesion? What property allows water to float? What is term for the process in which water vapor enters the atmosphere from plants? What type of bond holds water together?

Video to get started NASA on the importance of the water cycle

If you have notes, open them up! We are going to go through this week’s activities on the unique properties of water and connect them to biology. I would have your activity packet out so you can compare and not have to rewrite the answers.

Activity A. Why is the water cycle so essential to living things? The water cycle moves fresh water between the Earth’s atmosphere, its surface and the organisms living within the biosphere of Earth.

Activity H Draw the model of a water molecule Activity H Draw the model of a water molecule. What does each part represent? Why does it form this shape? Each line represents a shared pair of an electrons. One electron is from Hydrogen. One Electron is from Oxygen. They share electrons to be stable. Shared electrons form a covalent bond. These two spheres on the oxygen atom represent unshared electrons. These unshared electrons repulse and bend the shared electrons causing the water molecule to be bent.

Activity C Explain what is happening in the beaker. Draw it.

Why? Hydrogen bonding

Biological connection from http://www. pitara Only the top layer of the lake or river freezes. Underneath the frozen upper layer, the water remains in its liquid form and does not freeze. Also, oxygen is trapped beneath the layer of ice. As a result, fish and other aquatic animals find it possible to live comfortably in the frozen lakes and ponds.

Activity G HOT What temperature is the water Activity G HOT What temperature is the water? What is happening to the molecules of the water?

Biology connection: But why doesn’t the entire body of water freeze, like a giant, lake-sized ice-cube? Generally, all liquids expand on heating, but water is an exception to this rule. If water is heated, its volume gradually decreases. (This decrease in volume continues till the temperature rises to 4 °C.) At temperatures over 4 °C water starts expanding. It then keeps expanding with the further rise in temperature, till finally at 100 °C it turns into steam. In other words, at 4 °C, water has the least volume (occupies the least amount of space) and maximum density (is at its heaviest). This irregular expansion of water is called anomalous expansion. This anomalous expansion plays an important role by only freezing the upper layer in lakes and rivers.