What is the Internal Energy Reserve in Plants and Animals?

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Accepted Answer

Internal energy reserves are the stored forms of energy that plants and animals rely on during periods when external energy sources (like sunlight for plants or food for animals) are limited. These reserves act like biological “batteries,” ensuring survival, growth, and reproduction even under stress or scarcity.

Internal Energy Reserves in Plants

Plants produce energy through photosynthesis, converting sunlight into glucose. Since they cannot always photosynthesize (e.g., at night or during drought), they store energy in specific forms:

Starch – The primary energy reserve in most plants, stored in roots, tubers (potatoes), seeds, and stems.
Oils (lipids) – Found in seeds like sunflower, mustard, and groundnut; provide long-term, high-energy reserves.
Sucrose – Transport sugar in plants, often stored temporarily in leaves or stems.

During germination or stress, plants break down these reserves to release glucose for respiration and growth.

Also Check: What is Quasi Static Process?

Internal Energy Reserves in Animals

Animals obtain energy from food but store excess nutrients for future use. Their major energy reserves include:

Glycogen – The animal equivalent of starch, stored mainly in the liver and muscles; used for short-term, quick energy needs.
Fats (Triglycerides) – Stored in adipose tissues; the most concentrated energy reserve, used during fasting, hibernation, or migration.
Proteins (as a last resort) – In extreme starvation, body proteins may be broken down to supply energy, though this is not the primary pathway.

For example, bears rely heavily on fat reserves during hibernation, while humans use glycogen stores between meals and switch to fat metabolism during prolonged fasting.