1. Assimilation refers to the process that organisms transform nutrients obtained from the external environment into their own components or energy storage. That is, a series of metabolic pathways by which organisms use energy to synthesize small molecules into large molecules are important processes in biological metabolism.

2. Alienation refers to the molecules of organic nutrients (such as sugar, lipid, protein, etc.). ) is degraded from the environment or stored by cells into smaller and simpler final products (such as carbon dioxide, lactic acid, ethanol, etc.). ) Through step-by-step reaction.

3. From the point of metabolism, people go from fertilized eggs to adulthood because they absorb more nutrients than they consume.

Extended information 1. Biology can be divided into autotrophs and heterotrophs by assimilation.

1, autotroph: an organism that can synthesize its own organic matter from inorganic matter belongs to autotroph. Such as cyanobacteria, nitrifying bacteria and green plants.

2. heterotrophs: Organisms that can only ingest ready-made organic matter from outside belong to heterotrophs. Such as most animals and fungi.

Generally speaking, nitrification is a typical example of assimilation. The same is true of photosynthesis, because in this process, plants use carbon dioxide and sunlight to make their own food (organic molecules) and store these organic molecules in the plants themselves.

Generally speaking, all higher plants and some lower plants can carry out photosynthesis.

2. The types of alienation are aerobic, anaerobic and facultative anaerobic.

1, aerobic type

Most animals and plants need to live in an oxygen-rich environment. In the process of alienation, they must constantly absorb oxygen from the external environment to oxidize and decompose the organic matter in their bodies and release energy to maintain their own life activities. This metabolic type is called aerobic type, also called aerobic respiration type.

2. Anaerobic

Such organisms include some animals, such as lactic acid bacteria and parasites that live in animals. In the absence of oxygen, they can still oxidize the organic matter in the body and obtain the energy needed to maintain their own life activities. This type of metabolism is called anaerobic, also known as anaerobic respiration.

3. facultative anaerobic type

This organism carries out aerobic respiration under the condition of sufficient oxygen, completely decomposes organic matter into carbon dioxide and water, and incompletely decomposes organic matter into lactic acid or alcohol and water under the condition of lack of oxygen. A typical facultative anaerobic organism is yeast.

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