The need for photosynthesis

Explain that the sun is the ultimate source of energy for nearly all life on Earth.
Differentiate between producers and consumers and explain how energy flows from producers through consumers in simple food chains.
Describe the vital role of photosynthesis in maintaining the balance of oxygen and carbon dioxide levels in the atmosphere.

The sun is the ultimate source of energy for Earth, but animals can't directly use sunlight for energy.
Photosynthetic organisms, like plants and algae, are special because they can capture light energy from the sun using chlorophyll.
During photosynthesis, plants and algae use captured light energy to convert simple substances (carbon dioxide and water) into organic molecules, mainly glucose (a sugar).

Producers:
- Organisms like plants and algae are called producers because they produce their own food. They use simple substances from their environment (carbon dioxide, water) and energy from sunlight to make glucose (a sugar).
- These organic molecules form the essential energy store that fuels ecosystems.
Consumers:
- Animals are called consumers because they need to consume (eat) other organisms (plants or animals) to get their energy and nutrients.
- Herbivores (plant-eaters) get energy by eating plants.
- Carnivores (meat-eaters) get energy by eating herbivores (or other carnivores).
Whether you eat plants or animals, the energy in your food ultimately traces back to sunlight captured during photosynthesis.

Photosynthesis plays a critical role in maintaining the balance of gases in our atmosphere:

Producing Oxygen: As a byproduct of making glucose, photosynthesis releases oxygen into the air. This is the oxygen that animals, including humans, need to breathe for aerobic respiration. Without photosynthesis, there wouldn't be enough oxygen to support most animal life.
Removing Carbon Dioxide: Photosynthesis takes carbon dioxide out of the atmosphere to use it as a reactant. This helps to regulate the levels of carbon dioxide, an important greenhouse gas, in the atmosphere.

Sun (or Solar energy): The ultimate source of energy for most ecosystems on Earth.
Photosynthesis: The process used by producers to convert light energy into chemical energy in the form of glucose.
Producers: Organisms, like plants and algae, that make their own food using energy from sunlight.
Consumers: Organisms that obtain energy by eating other organisms (producers or other consumers).
Food chains: Diagrams that show the flow of energy from one organism to another in an ecosystem.
Oxygen: A gas produced during photosynthesis that is essential for the respiration of most animals.
Carbon dioxide: A gas used by plants in photosynthesis, taken from the atmosphere.
Atmosphere: The layer of gases surrounding the Earth, where the balance of oxygen and carbon dioxide is maintained by photosynthesis.
Ecosystems: Communities of living organisms interacting with each other and their physical environment.

Construct or interpret simple food chains involving different producers and consumers, explaining the direction of energy flow from the sun through the organisms.
Investigate the impact of human activities, such as deforestation or pollution affecting photosynthetic organisms, on the balance of gases in the atmosphere and the stability of food chains.