Learning Objectives/Practice Questions · Helmont’sExperiment •Although Van Helmont did not realize it, carbon dioxide in the air made a major contribution to the mass of his

Lesson Overview Energy and Life

Learning Objectives/Practice Questions

1a) Where does the mass of a tree come from?

1b) Summarize van Helmont’s experiment. What was his conclusion? Identify a flaw in his experiment, and suggest a way he could have addressed this flaw.

2) What are ADP and ATP? How are they similar? Different?

3) Explain how the ADP-ATP system is like a battery.

4) Summarize the two main ways that living organisms can obtain energy. Give examples of each.


Where does the mass of a tree come from?



a) The soil

b) The water

c) The air

d) The sunlight

e) Other?

Design an experiment to test your prediction.


Caution: wordy borrowed slides ahead!


Helmont’s Experiment

• Dutch physician Jan Van Helmont devised an experiment to determine how plant growth actually works

• Found the mass of a pot of dry soil and a small seedling• Planted the seedling in the pot of soil

• Watered regularly for 5 years

• Result: tree gained about 75 kilograms; mass of soil unchanged

• Conclusion: most of the mass must come from water because that is all he added to the pot



What was a flaw in his experiment?



a) The soil

b) The water

c) The air

d) The sunlight

e) Other?


Video

https://www.youtube.com/watch?v=2KZb2_vcNTg



a) The soil

b) The water

c) The air

d) The sunlight

e) Other?




• Although Van Helmont did not realize it, carbon dioxide in the air made a major contribution to the mass of his tree

• It is the carbon in carbon dioxide that is used to make carbohydrates in photosynthesis


Priestley’s Experiment

• Took a candle, placed a glass jar over it, and watched as the flame gradually died out• Something in the air was necessary to keep a candle

burning•When that substance was used up, the candle went

out


Priestley’s Experiment

•Priestley then placed a spring of mint under the jar and allowed a few days to pass, the candle could be relighted and would remain lighted for awhile

•The mint had produced the substance required for burning


Plants produce oxygen!



Lesson Overview

8.1 Energy and Life

(6-1 Equivalent)


Discussion:

- What is energy?

- What do cells use it for?

- What is the law of conservation of energy? What are the implications for cells?


Chemical Energy and ATP

Energy is the ability to do work.

Cells use energy to:

• Build new molecules

• Contract muscles

• Transport substances across cell membranes

Without the ability to obtain and use energy, life would cease to exist.


Chemical Energy and ATP

• Adenosine triphosphate (ATP):

• An important compound used to store and release energy

• Made of: adenine, a 5-carbon sugar called ribose, and three phosphate groups


Storing Energy

• Adenosine diphosphate (ADP):

• Differs from ATP: two phosphate groups

• Also stores energy (less than ATP)

• ADP is like a rechargeable battery:• Extra energy used to add

phosphate group to ADP; makes ATP


Releasing Energy

• Cells can release the energy stored in ATP by breaking the bonds between the second and third phosphate groups.

• Because a cell can add or subtract these phosphate groups, it has an efficient way of storing and releasing energy as needed.




Using Biochemical Energy: Examples

Active transport:

• Uses ATP energy to move substances across membrane

• Maintains balance of ions on each side of membrane

• Examples:

• Proton pumps

• Sodium-potassiumpumps in most cellmembranes



ATP powers movement, providing the energy for motor proteins that contract muscle and power the movement of cilia and flagella.

•



Energy from ATP powers the synthesis of proteinsand responses to chemical signals at the cell surface.


Using Biochemical Energy

• ATP best used for short-term energy storage

• Most efficient: keep a little bit of ATP at a time

• Cells can regenerate ATP from ADP as needed by using the energy in foods likeglucose


Heterotrophs and Autotrophs

Discussion:

- How do you get your energy?

- What are some other ways that organisms get their energy?



Heterotrophs: organisms that obtain food by consuming other living things



Autotrophs: organisms that make their own food

Photosynthesis:

• Process where autotrophs use sunlight energy to produce high-energy carbohydrates that can be used for food

• Plants, algae, and some bacteria

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Learning Objectives/Practice Questions · Helmont’sExperiment •Although Van Helmont did not realize it, carbon dioxide in the air made a major contribution to the mass of his