An animal's inputs of energy and materials would exceed its outputs
a. If the animal is an endotherm, which must always take in more energy because of its high metabolic rate
b. If it is actively foraging for food
c. If it is growing and increasing its mass
d. Never; due to homeostasis, these energy and material budgets always balance

Verified step by step guidance

1. Understand the concept of energy balance in animals: Energy balance refers to the relationship between the energy an animal takes in (through food) and the energy it expends (through activities and metabolic processes).
2. Consider the conditions under which an animal might take in more energy than it expends: This typically occurs during periods of growth, when the animal is building new tissues and increasing its mass.
3. Evaluate the options given in the problem: a) Endotherms have high metabolic rates, but this doesn't necessarily mean their energy input exceeds output. b) Actively foraging animals expend energy, which might not lead to a net gain. c) Growing animals require more energy for building tissues, which can lead to energy input exceeding output. d) Homeostasis aims for balance, but doesn't account for growth phases.
4. Focus on option c: Growing animals are in a phase where they are increasing their mass, which requires additional energy and materials beyond their immediate metabolic needs.
5. Conclude that during growth, an animal's energy and material inputs can exceed its outputs, as it is storing energy and materials for building new tissues.

Key Concepts

Endothermy

Endothermy refers to the physiological capability of an organism to maintain a stable internal body temperature through metabolic activity. Endotherms, such as mammals and birds, have high metabolic rates to generate heat, requiring substantial energy intake to sustain their body temperature, especially in varying environmental conditions.

Energy Balance in Growth

During growth, an organism's energy and material inputs often exceed outputs as it accumulates biomass. This surplus is necessary for synthesizing new tissues and supporting increased metabolic demands. Growth phases require additional nutrients and energy, leading to a positive energy balance until the organism reaches maturity.

Homeostasis

Homeostasis is the process by which biological systems maintain stability while adjusting to changing external conditions. It involves regulatory mechanisms that balance inputs and outputs of energy and materials to sustain optimal internal conditions. However, during certain life stages or activities, temporary imbalances can occur, such as during growth or intense physical activity.