1. Ch. 5 – Cycles in the Biosphere Bio – means “life”
Lesson 1
Oxygen & Carbon Dioxide

2. Photosynthesis & Respiration
Plants provide oxygen & food because they can carry out photosynthesis.
Photosynthesis is a process during which energy from the Sun is used to change carbon dioxide & water into glucose & oxygen.
The simple glucose provides energy for plants, for animals that eat the plants, & then for animals that eat other animals. The oxygen is released into the atmosphere.

3. Photosynthesis – cont.
Plants are not the only organisms that conduct photosynthesis. Tiny algae that live in water also carry out photosynthesis.
Essay question – In fact, algae in the ocean supply most of Earth’s oxygen.
What might happen if all of the algae in the world’s oceans suddenly stopped carrying out photosynthesis?
If these algae were unable to carry out photosynthesis, the atmosphere would have much less oxygen.

4. Photosynthesis – Cont.
During photosynthesis, the light energy from the Sun is converted into chemical energy. This energy stored in food. Living things need that energy to carry out all of their life processes.

5. Photosynthesis:
Carbon dioxide + water + energy  glucose + water
Respiration:
Glucose + oxygen  carbon dioxide + water + energy
Photosynthesis & respiration can be thought of as opposite processes. Plants produce oxygen that animals need & animals produce carbon dioxide that plants need.
The products of respiration are used for photosynthesis. In this way, oxygen & carbon dioxide keep cycling through the biosphere

6. Respiration
The way that most organisms are able to use the energy in food is through respiration.
Respiration is the process through which oxygen & glucose are combined to produce carbon dioxide & water.
During this process, stored energy is released.
Both plants & animals perform respiration.
Respiration is why oxygen is so important to life on Earth.

7. Respiration – Cont.
You take in oxygen with every breath. The blood carries it to cells throughout the body, where respiration constantly takes place.
The relationship between photosynthesis & respiration is one way that organisms depend on one another.
Animals & other organisms need plants for food & oxygen. Plants rely on other organisms for carbon dioxide.

8. Why is respiration necessary for both plants and animals?
They both use the process to release energy stored in sugar.

9. Carbon
Carbon is the 4th most abundant element on Earth & is the basic part of all living things.
Carbon is found in the Earth’s crust as fossil fuels such as coal, oil, & natural gas.
Carbon moves through our in environment through cycles

10. Carbon Cycle
Carbon moves through the carbon cycle mostly as carbon dioxide gas.
There are 4 ways carbon moves through the environment.
Photosynthesis – by plants, carbon dioxide is used
Respiration – plants and animals; carbon dioxide is produced
Decomposition – the break down of dead organisms; carbon dioxide is produced
Combustion (Burning) of fossil fuels - to run our cars, heat our homes, the making of products; carbon dioxide is produced

11. Oxygen
The flow of oxygen through the environment is essential for life.
Less than 1 % of the atmosphere consists of carbon dioxide, but oxygen makes up nearly 21 % of the atmosphere.
Like carbon, oxygen also cycles through the environment.

12. Oxygen Cycle Oxygen is produced during photosynthesis
Consumed during respiration
When water is evaporated into the atmosphere oxygen is produced, it is broken down chemically.
Oxygen is also consumed during combustion, rusting & when rocks are weathered.
Because oxygen is part of carbon dioxide, the oxygen cycle is linked to the carbon cycle. Both elements cycle between living & nonliving things in the environment. Look at diagram in text on pgs. B8&9

13. Events on Earth can upset these cycles – Essay question
If people slash & burn rainforests, photosynthesis decreases. Less oxygen will enter the atmosphere & less carbon dioxide will leave. If respiration were to increase (population increase), more oxygen would leave the atmosphere & more carbon dioxide would enter.
Read “Disrupting the Cycle” textbook pg. B10

14. What are some causes of increasing carbon dioxide in the environment?
Burning more fossil fuels leads to greater amounts of carbon dioxide in the atmosphere, & deforestation results in less carbon dioxide being removed from the atmosphere.

15. Ch. 5 Lesson 2 Nitrogen & Water
Most of Earth’s water is in the oceans. Most of the nitrogen is a gas in the air. Living things use both water & nitrogen, which cycle between Earth’s surface and atmosphere.

16. Nitrogen & Water
Nearly 80% of Earth’s atmosphere consists of nitrogen gas.
Plants & animals need nitrogen to form proteins & other important compounds. However, most living things cannot use nitrogen in the form in which it occurs in the atmosphere. It has to be converted to a usable form.
The process of changing nitrogen gas into usable nitrogen compounds is nitrogen fixation.

17. Nitrogen fixation
There are 2 main things responsible for nitrogen fixation: lightening & bacteria
Lightening – the energy released by lightening acts to combine nitrogen and oxygen in the air. The new compounds dissolve in rainwater.
Special bacteria – this produces most of the nitrogen fixation. Some bacteria live in soil, water, or on roots of some plants.

18. Nitrogen Cycle

19. Nitrogen cycle
Human activities can disrupt the nitrogen cycle, resulting in a shortage or surplus of usable nitrogen in the soil. When crops are harvested, the nitrogen in the plants leaves with the plants & does not return. Erosion & irrigation can also wash nitrogen out of the soil.
To replace nitrogen, farmers add nitrogen-rich fertilizers. They also plant peanuts or other plants that general support the special bacteria that produce nitrogen fixation.

20. Lets image we planted 2 plants at the same time
Lets image we planted 2 plants at the same time. They have received the same amount of water & sunlight, but for some reason Plant B is much taller then Plant A. Can you give a reason why they may be different and how we might improve Plant A’s growth?
Plant A may not be getting as much nitrogen as Plant B. Plant A’s growth might be I improved by adding nitrogen-rich fertilizer to the soil.

21. Water in the Environment
All living things are made up mostly of water. Living things need water to carry out life processes.
Water as a cycle through the environment like carbon & nitrogen.
Most of Earth’s water is contained in oceans & is salty. Fresh water is found in lakes, rivers, & streams. Some water is underground. Water is also frozen in snow, ice, glaciers, & polar ice caps.
Water in the atmosphere is water vapor & tiny droplets of water or ice in clouds.

22. Water cycle
The water cycle is the continuous movement of water from Earth’s atmosphere & back to the surface.
Water cycles over & over again Earth’s air, ground, oceans, & living things. The power for the water cycle comes from the Sun. Without it, water would stay in the oceans.

23. Water Cycle Process Evaporation & Transpiration
Energy from the Sun causes water in the oceans & on land to heat up. When this happens, water evaporation increases. During, evaporation, water consumes energy & changes from the liquid state to the gas state. Water in the gas state is called water vapor.
Plants also release water into the atmosphere. The process through which water evaporates from a plant’s leaves is known as transportation.

24. Water Cycle Process – Cont.
Precipitation
Water vapor in the atmosphere can condense into tiny droplets of water and form clouds. When the droplets become heavy enough, they fall to Earth as rain, sleet, hail, or snow. Water that falls to the Earth from a cloud is called precipitation.
Most precipitation falls on Earth’s oceans. The precipitation that falls on land is either absorbed into the ground or flows to a body of water. Then the cycle continues. Look at diagram in Txt. pg. B17

25. Describe the role of trees & other plants in the water cycle – Essay question
During transpiration, water evaporates from the leaves of plants and enters the atmosphere as water vapor. Water vapor will condense to form clouds. Eventually, the water will fall back to Earth’s surface as precipitation.

26. Water Conservation
Although almost ¾ of Earth’s surface is covered with water, about 97% of Earth’s water is salt water in oceans.
Of the remaining 3%, less than 1% is usable fresh water. This water is not spread evenly around Earth.
Water Conservation is key to survival.

27. Ch. 5 Lesson 3 Food Chain
Energy moves in one direction through the ecosystem from producers to consumers

28. Trophic Levels
Organisms that make food are known as autotrophs or producers. Plants (which include trees) & algae are producers.
Energy is stored in food. A plant uses some of the energy for its own life processes. It stores the rest. An animal that eats a plant obtains the stored energy. It then uses some of the energy & stores the rest. If another animal then eats the 1st animal, it obtains the stored energy. In this way, energy flows through an ecosystem.

29. Trophic Levels – Cont.
Suppose, for example, that a mouse eats a plant. Energy is transferred from the plant to the mouse. If a hawk then eats the mouse, energy is transferred from the mouse to the hawk. Each step in the movement of energy is known as a tropic level. Look at diagram in txtbook pg. B25
This is an example of a food chain,also.

30. Trophic Levels – Cont.
The lowest level on the trophic level is the producers – trees, ferns, mosses, algae
The second level is the Primary consumers, this consists of heterotrophs – organisms that can not make their own food. – squirrels, deer, seed-eating birds, insects, herring & other small fish, baleen whales.
The third and last level is the Secondary Consumers, an organisms that eats a primary consumer

31. Trophic Levels – Cont.
Note that energy flows in one direction, from producers up through the trophic levels.
In nature, food chains & trophic levels may overlap. Some animals eat both producers & primary consumers. For example, bears eat fruit & fish. Some of the fish they eat may be secondary consumers that eat other fish.
Overlapping food chains in an ecosystem for a food web.

32. Scavengers & Decomposers
Scavengers are organisms that live off dead animals. Example of large scavengers: vultures, hyenas, & ravens. Many insects are scavengers too.
Scavengers help the break down of a dead organism.
Dead organisms that are left to decompose, meaning to rot or break down, are food for decomposers.
Organisms called decomposers live by breaking apart dead organic matter into simpler parts.

33. Decomposers- Cont.
Bacteria are Earth’s most important decomposers. Fungi & many protists are decomposers, too.
Decomposers play a very important role by breaking down old organisms, they return minerals & nutrients to the soil.
What is the relationship between decomposers & other organisms? – Essay question
Decomposers break down the wastes of other organisms themselves when they die. They return chemicals to the soil to be used by other organsism.

34. Energy Pyramid
We talked how energy is transferred to one trophic level to the next, but remember, only the stored energy can be transferred.
A energy pyramid is a model that shows how energy moves from one level to another. It shows that there is more energy available for use at lower trophic levels. Only about 10% of the energy from each level is passed on to the next level.
Look at energy pyramid in Txtbook pg. B27

35. Energy Pyramid- Cont. Scientists also use a pyramid of biomass.
A pyramid of biomass is a model that shows how much organic matter each trophic level produces.
Only about 10% of the biomass from each level is passed on to the next level.
Read Pg. B28 and learn about The energy pyramid & Agriculture.

36. Suppose that the number of secondary consumers in an ecosystem increased. How might this change affect other organisms in this ecosystem? – Essay question
If the number of secondary consumers increased, they would eat all the primary consumers. The secondary consumers would then have no food, which could cause their populations to get smaller.