Now consider the big oak tree at the edge of the field.

The oak tree in the sun, full of green leaves.

Nobody feeds the oak tree either. Its leaves make its food, using sunlight.

The oak tree: does it make its own food? Yes, using sunlight.

Now consider the green stuff floating on the pond by the fence. Those tiny green specks are pond algae.

Pond algae: tiny green living things floating on the water.

Pond algae have no leaves. But they are green, and they make their own food, using sunlight.

Pond algae: do they make their own food? Yes, using sunlight.