Food and Energy

Students investigate the importance of energy and matter for cells by creating models that show the flow of matter and energy that occurs in cellular respiration and photosynthesis.

• Photosynthesis and cellular respiration are processes that allow cells to access energy.
• Knowing how organisms access energy is essential for understanding life itself because living things depend on a steady flow of energy to power all tasks needed for survival.
• To understand why food holds stored energy, it is important to start with the energy source. For deep-sea organisms, that energy source comes from deep within Earth’s interior. For most other organisms, that energy begins with the sun.
• Plants are an important part of most ecosystems on Earth because unlike animals or other organisms, plants are able to use the sun’s energy to make glucose, which has stored energy and can be used as building material for growth and development.
• Cellular respiration cannot happen without glucose or oxygen, and photosynthesis is the process that produces glucose and oxygen. At the same time, photosynthesis cannot happen without carbon dioxide, and cellular respiration produces carbon dioxide.

• Why do all animals need to eat food?
• What would happen at the cellular level if an organism stopped eating?
• How does food provide us with energy?
• Why are the nutrients in food important for organisms?
• Why is photosynthesis a chemical reaction?
• How would you describe the inputs and outputs required for photosynthesis?
• How do cellular respiration and photosynthesis depend on each other?

Misconception: Human cells are completely different from other animal cells, plant cells, and prokaryotic cells.

Fact: All cells, whether human, plant, or prokaryote, share certain similarities. All cells must perform essential life fun

Cellular respiration : the process in which oxygen is used to convert some of the energy in glucose into energy that is stored in molecules called adenosine triphosphate, or ATP

Nutrients : the chemicals that organisms need for energy and for building and maintaining the parts of a cell

Photosynthesis : the process of turning sunlight, carbon dioxide, and water into glucose and oxygen

Organisms in the Dark

Dr. Cindy Van Dover and a team of scientists spent 40 days sailing around the Indian Ocean. They were studying a newly discovered deep-sea hydrothermal vent.

Hydrothermal vents form along mid-ocean ridges, in places where the seafloor moves apart very slowly because of Earth’s tectonic plates. As the cold ocean water flows into the cracks in the seafloor, it is warmed by the hot interior. This causes a scalding hot mixture of water and minerals to get pushed upwards.

The scientists found dozens of red and white worm-like organisms growing around the hydrothermal vents. These tubeworms are 0.9 meters (3 feet) long. They have no eyes, no mouth, and no intestines.

Scientists are particularly interested in where the organisms deep under the ocean get energy to survive. Remember that all cells—and therefore all living things—need energy to survive. Unlike most organisms on Earth, the energy that supports life deep in the sea comes from within Earth itself.

As the scalding hot water erupts, it carries with it hydrogen sulfide and other molecules that contain chemical energy. Deep-sea bacteria take in the molecules to access that chemical energy, which they use to produce sugars that fuel their life processes. The tubeworms and other organisms eat the bacteria, accessing some of the energy to support their own life functions.

Energy and Matter Interact

Knowing how organisms access energy is essential for understanding life itself. Energy is essential for cells because every cell is constantly working, carrying out all of its essential life functions. Because of this, cells are never static or unchanging. In fact, all cells are always changing, generating energy, building proteins, transporting materials, and getting rid of waste.

All animals, including humans, get energy and nutrients when we eat and drink. Nutrients are the chemicals that organisms need for energy and for building and maintaining the parts of a cell. Nutrients include carbohydrates, fats, and proteins, as well as vitamins, minerals, and water.

In this lesson, students investigate science phenomena on the connection between cellular respiration and photosynthesis by creating models that show the flow of matter and energy that occurs in these processes. Students use their models to figure out how energy and matter interact in cells to allow for the growth, development, and survival of an organism.