Black bears can hibernate for up to 7 months without food or water (lines 1–2) - AQA - A-Level Biology - Question 10 - 2020 - Paper 1

Black bears are able to survive for extended periods without food or water during hibernation due to several physiological adaptations.

First, they rely on fat stores accumulated during the pre-hibernation period. Fat is metabolized for energy, which provides the necessary calories to sustain basic metabolic functions. This process leads to decreased energy requirements as the bears enter a state of lower metabolic activity, enabling them to preserve energy efficiently.

Secondly, the bears' metabolism slows significantly during hibernation, reducing the overall need for food and water. This lower metabolic rate is facilitated by hormonal changes that decrease the heart rate and overall energy expenditure. Additionally, the bears enter a state of torpor, where they significantly lower their movement, which further conserves energy.

In summary, the combination of fat utilization, reduced metabolic demands, and decreased activity makes it feasible for black bears to undergo prolonged periods of hibernation without needing food or water.