1. Ingestion and Digestion:
* Ingestion: The animal takes in food through its mouth.
* Mechanical Digestion: The food is physically broken down into smaller pieces through chewing (in the mouth) and churning (in the stomach).
* Chemical Digestion: Enzymes secreted by the digestive system break down large food molecules into smaller, soluble molecules.
2. Absorption:
* The small, soluble molecules (e.g., amino acids, sugars, fatty acids) are absorbed from the digestive tract into the bloodstream.
3. Transport:
* The bloodstream carries these absorbed nutrients throughout the body, delivering them to individual cells.
4. Cellular Respiration:
* Cells use the absorbed nutrients (mainly glucose) as fuel for cellular respiration. This process generates energy (ATP) that powers cellular functions.
5. Biosynthesis (Building Complex Molecules):
* Protein Synthesis: Amino acids absorbed from the bloodstream are used to build new proteins.
* Lipid Synthesis: Fatty acids and glycerol are used to synthesize new lipids (fats and oils).
* Carbohydrate Synthesis: Glucose is used to synthesize complex carbohydrates, like glycogen, for energy storage.
* Nucleic Acid Synthesis: Building blocks from digested food are used to synthesize new DNA and RNA.
6. Cellular Growth and Repair:
* Newly synthesized molecules are used for cell growth, repair, and maintenance.
Therefore, the correct order of events is:
1. Ingestion and Digestion
2. Absorption
3. Transport
4. Cellular Respiration
5. Biosynthesis
6. Cellular Growth and Repair
