1. Autotrophs: These organisms make their own glucose through photosynthesis. This process uses sunlight, water, and carbon dioxide to produce glucose and oxygen. Examples of autotrophs include plants, algae, and some bacteria.

2. Heterotrophs: These organisms obtain glucose by consuming other organisms. They eat plants (herbivores), animals (carnivores), or both (omnivores). The glucose in their food is broken down through digestion and absorbed into the bloodstream.

Here's a breakdown of how each method works:

Photosynthesis:

1. Light-dependent reactions: Sunlight is captured by chlorophyll in chloroplasts, converting light energy into chemical energy in the form of ATP and NADPH.

2. Light-independent reactions (Calvin cycle): Carbon dioxide is taken in from the atmosphere and combined with ATP and NADPH to produce glucose.

Heterotrophic Nutrition:

1. Ingestion: Organisms consume food containing glucose.

2. Digestion: Enzymes break down complex carbohydrates (like starch) into simpler sugars, including glucose.

3. Absorption: Glucose is absorbed into the bloodstream through the intestines.

In both cases, the glucose is then transported to the cells where it is used as fuel in cellular respiration.

Important Note:

* Some organisms can use other sources of energy for cellular respiration, such as fats and proteins.

* Cellular respiration is a complex process that occurs in multiple stages, but the ultimate goal is to convert glucose into energy in the form of ATP.