Fruits preserved in cold storage chambers last longer because the low temperature reduces their metabolic activity and slows the rate of respiration of the fruits.

Introduction / Context:
Cold storage of fruits is a common post harvest technology used to keep fruits fresh for a longer period of time. Consumers often notice that fruits kept in a refrigerator or cold store spoil more slowly than fruits kept at room temperature. This question tests your understanding of why low temperature extends the shelf life of fruits, focusing on the biological process of respiration rather than simple ideas like darkness or humidity.

Given Data / Assumptions:

• Fruits are living tissues that continue to respire after harvest.
• Cold storage means the temperature is significantly lower than normal room temperature.
• We assume that no other major preservation chemicals are being added, so the main factor is temperature.
• Fruit quality is affected by the rate of ripening and the growth of microorganisms.

Concept / Approach:
After harvest, fruits are still alive and continue to carry out respiration. In respiration, stored sugars are broken down to release energy, carbon dioxide and water. This process is essential for the fruit cells but also leads to ripening and eventual senescence or ageing. The rate of respiration is strongly influenced by temperature. At lower temperatures, enzyme activity slows down and respiration rate decreases. When respiration slows, the ripening and ageing processes also slow, and fruits stay firm and edible for a longer time. Therefore the key reason for longer storage life in cold conditions is reduced respiration, not increased oxygen or darkness.

Step-by-Step Solution:
Step 1: Recall that fruits are living organs which continue to respire even after being picked from the plant. Step 2: Understand that respiration uses stored food in the fruit and produces energy, carbon dioxide and water, leading gradually to ageing and softening. Step 3: Remember that enzyme controlled reactions such as respiration are slower at low temperatures. Step 4: Recognise that in a cold store, the temperature is lowered to reduce respiration rate and thereby slow ripening and spoilage. Step 5: Match this reasoning with the option stating that the rate of respiration of the fruits is decreased at low temperature.

Verification / Alternative check:
In horticulture and food science, charts of respiration rate versus temperature show that climacteric fruits such as bananas, apples and mangoes respire rapidly at warm temperatures but much more slowly in cool conditions. Cold storage is carefully designed to maintain an optimum low temperature that is above the chilling injury level but low enough to slow metabolic activity. This scientific evidence supports the statement that reduced respiration is the main reason for extended shelf life in cold stores.

Why Other Options Are Wrong:
Option a suggests that exposure to humidity is increased, but high humidity alone does not guarantee longer life and can even encourage fungal growth if not controlled.
Option b states that more oxygen is available, but excess oxygen could actually speed up respiration and spoilage rather than slow it.
Option c claims that fruits last longer simply because they are stored in a dark place, but darkness by itself does not significantly slow respiration compared to temperature reduction.

Common Pitfalls:
Many learners think that fruits stop all biological activity after harvest, which is not true. Another common misconception is that darkness is the main factor in preservation, similar to how light affects some chemical reactions. In reality, the most important factor in cold storage is temperature control, which directly influences respiration rate and enzyme activity. Understanding the relationship between temperature and metabolism helps avoid these misunderstandings.

Final Answer:
Fruits last longer in cold storage because the rate of respiration of the fruits is decreased at low temperature.