Read “Biology: Exploring Life” pp. 81-86

1. What does it mean that water is a polar molecule? Draw two water molecules in the space below and explain how they can be compared to two magnets.• Polar = one end has +

charge, the other –

• The + end of one molecule is attracted to the – end of another.

In magnets and molecules….opposites attract

2. How does cohesion and adhesion of water molecules help plants?

Water molecules’ attraction to each other (cohesion) and to the walls of plant veins (adhesion) enables water to get from roots of trees to tops.

3. Explain two different ways water can moderate temperatures (keep temperatures from becoming too hot or too cold).

• Water in sweat helps cool you down.• Large bodies of water store heat energy

from the sun during the day, keeping land cool.

• At night, they give off heat, keeping land warm.

4. How does the low density of ice help support life on Earth?

• When water in lakes freezes, it floats.

• This forms a blanket on top, keeping heat in and keeping rest of lake from freezing solid.

5. How does water’s ability to dissolve other substances help support life on Earth?

Enables living things to transport oxygen, nutrients, waste in bodies dissolved in water or blood.

6. How does the Earth’s distance from the sun help living things use water?• Not so close to sun that water boils away.

• Not so far that water all frozen.• Water can move around planet as liquid and gas. • Can be stored as solid in winter to be used later in summer.

Ingredients for Life: Water

https://www.youtube.com/watch?v=XtctQxn4eHM

Why does life on Earth depend on water? Where else in the solar system are we most likely to find water and/or life?

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times.

“Our quest on Mars has been to ‘follow the water,’ in our search for life in the universe, and now we have convincing science that validates what we’ve long suspected,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington. “This is a significant development, as it appears to confirm that water -- albeit briny -- is flowing today on the surface of Mars.”

Finish for homework! (slideshow on class website)

7a. What percent of the world’s water supply is fresh and drinkable? Color in the Prediction bar graph below:

Green = salt water red = frozen fresh water (glaciers, ice caps) blue = liquid fresh water

Prediction:5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

  

7b. Go to the “Water: A Freshwater Story” link on the class website to find the actual percentages and color accordingly in the bar graph below.Actual:Green = salt water red = frozen fresh water (glaciers, ice caps) blue = liquid fresh water

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

  

• 97.5% salt water• 2% frozen water in ice caps• Less than 0.5% fresh liquid water (lakes, rivers, etc.)

8. What are 5 good ways to conserve water in your everyday life?

• Turn off when brushing teeth.• Water plants in morning or evening.• Take shorter showers.• Use Energy Star appliances.• Tell your elected rep to make

farmers, industries use less water.