Cycles in NatureUnit B Chapter 1 Life Science

Investigation: How Plants Use Carbon Dioxide 1. PUT ON SAFTEY GOGGLES! LEAVE THEM ON UNTIL #4

IS COMPLETED! Fill one beaker about two-thirds full of water. Use the dropper to add BTB to water until the solution turns blue. BTB is an indicator of carbon dioxide when it turns blue.

2. DO NOT SUCK ON THE STRAW OR SWALLOW THE SOLUTION! Put the plastic straw in the solution and blow into it. What do you observe? Record your observations.

3. Put the elodea into one test tube, and use the funnel to fill the tube with BTB solution from the beaker. The other test tube will only be filled with BTB.

4. Seal the test tubes with caps. Carefully turn them upside down. Place them in the empty beaker.

5. Place container by sunny window. Predict what changes will occur in each test tube. Observe the next day and record observations.

Brainstorm!

Silently read pages B2-B3. With your group, create three questions you have about the chapter.

Lesson 1: How Natural Materials are Reused Natural Cycles Earth’s materials are

constantly being cycled among organisms and the environment.

The air we breath has large amounts of oxygen, nitrogen and carbon.

Nitrogen Cycle

78% of Earth’s atmosphere is made of Nitrogen, but most organisms can’t use nitrogen in this form.

Nitrogen Cycle – Nitrogen gas is fixed, or changed into forms of nitrogen that plants can use. Two forms of fixed nitrogen are:

1. Ammonia 2. Nitrates

Bacteria in soil and lumps on roots can fix nitrogen. Nitrogen can also be fixed by lightening. Finally, nitrates and ammonia are returned to the soil

through waste and decaying protein.

The Nitrogen Cycle

Carbon – Oxygen Cycle Carbon –Oxygen Cycle –

use two processes to cycle carbon and oxygen through the environment:1. Photosynthesis2. Respiration

Photosynthesis: - Process in which, plants take in carbon dioxide and release oxygen.

Respiration: - the process that releases energy from food. Oxygen is taken from air or water and carbon dioxide is released into the environment.

Changing the Balance What problems could cutting down Earth’s forests

cause? Why is too much Carbon Dioxide in the atmosphere

bad? What can humans do to reduce CO2 in the atmosphere?

Review Questions1. Name two places where carbon is stored?

Ocean and Atmosphere 2. Where do bacteria fix nitrogen gas?

In roots and soil3. How do photosynthesis and respiration affect the carbon-oxygen cycle.

Photosynthesis removes carbon dioxide from the air and adds oxygen, Respiration does the opposite.

4. How might building a shopping mall on land where there is now a park affect the amount of carbon dioxide in the air?

It would increase carbon dioxide in the air.5. Which human activity does NOT increase the amount of carbon dioxide in the air?

a) Cutting down treesb) Heating buildings with coalc) Driving carsd) Planting corn

Lesson 2:Why is the Water Cycle Important

THINK! How much of Earth’s surface is covered in water How much of that water is fresh water?

Water Cycle

Evaporation – the process of liquid water changing to a gas (water vapor).

Condensation – water vapor changing back into liquid water.

Precipitation – any form of water that falls to Earth.

Transpiration - plants and animals putting water back into the environment.

Continued…

Why do you think it’s important to conserve water?

What begin the water cycle process?

Humans and the Water Cycle

Less that 1 % of Earth’s fresh water can be used.

Most is frozen in polar ice caps.

Humans can harm fresh water supplies through fertilizers and soil that carry harmful chemicals.

Conserving water is very important.

How can you conserve water?

Review Questions1. What is the process by which liquid water becomes water vapor?

Evaporation2. What is the process by which water vapor becomes cloud droplets?

Condensation3. Where is most of Earth’s fresh water?

Ice Caps, Glaciers4. What do you think causes dew to form on plant leaves during a cool night?

As temperatures fall, water vapor condenses in the air and leave drops on the leaves.

5. About how much of all the fresh water on Earth can be used by people and other land organisms?

a) Less than 1%b) More than 10%c) More than 95%d) 100%