You're right! Organisms that perform photosynthesis, like plants, algae, and some bacteria, are able to convert sunlight into energy. Other organisms, like animals, fungi, and many bacteria, can't do this.

Here's how they generate energy instead:

1. Cellular Respiration: This is the primary way most organisms obtain energy. It involves breaking down glucose (a sugar) in the presence of oxygen to release energy. This process happens in the cells of all living things.

2. Chemosynthesis: Some organisms, mainly bacteria, can obtain energy from the oxidation of inorganic compounds like hydrogen sulfide, methane, or ammonia. This process is similar to photosynthesis in that it uses chemical energy to build organic molecules.

3. Heterotrophy: Many organisms cannot produce their own food and must consume other organisms to obtain energy. This is known as heterotrophy. There are different types:

* Herbivores: Eat plants

* Carnivores: Eat other animals

* Omnivores: Eat both plants and animals

* Decomposers: Break down dead organisms and waste products

In summary:

* Photoautotrophs (like plants) use sunlight for energy.

* Chemoautotrophs use chemical energy from inorganic compounds.

* Heterotrophs consume other organisms for energy.