Problem 5 - Campbell Biology

Question

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.

Step-by-Step Solution

Answer

Option (C)

Step 1: Understand the Question

The question asks under which condition an animal's inputs (energy/materials taken in) would surpass its outputs (energy/materials expended).

Step 2: Analyze Option (A)

Option (A) states that if the animal is an endotherm, it must intake more energy due to its high metabolic rate. While endotherms do have high metabolic rates, this doesn’t necessarily mean their inputs will always exceed their outputs.

Step 3: Analyze Option (B)

Option (B) suggests that an animal actively foraging for food will have inputs exceeding outputs. Foraging requires energy expenditure, so this may not result in a surplus of inputs.

Step 4: Analyze Option (C)

Option (C) states that if an animal is growing and increasing its mass, its inputs would exceed outputs. Growth involves consuming more energy and materials than it expends to support tissue development and increase in biomass.

Step 5: Analyze Option (D)

Option (D) claims that due to homeostasis, energy and material budgets always balance. Homeostasis regulates internal conditions, but growing animals still take in more energy and materials than they expend.

Step 6: Select the Correct Option

Based on the analysis, Option (C) is the correct answer as growing animals typically have inputs exceeding their outputs to support growth and mass increase.

Key Concepts

endotherms

Endotherms are animals that maintain a constant body temperature by producing heat internally. This characteristic is usually found in mammals and birds. The metabolic processes in endotherms require a significant amount of energy because they need to keep their body warm even when the environmental temperature is low. Maintaining such body temperatures involves:

• Higher food consumption
• Faster metabolism
• Constant internal body temperature regulation

However, this doesn’t always mean their energy inputs exceed their outputs. The relationship between their energy intake and expenditure is complex and often balanced unless specific conditions, like growth or illness, alter it.

metabolic rate

Metabolic rate refers to the speed at which an animal's body converts food into energy. This process includes all chemical reactions occurring in the body to maintain vital functions such as breathing, circulation, and cell repair.

Animals with a high metabolic rate, like endotherms, require more frequent and substantial energy intake because:

• They expend more energy on maintaining body heat
• They need to support their higher energy needs
• They engage in more activity and movement

In essence, metabolic rate is a measure of energy turnover, essential for understanding how animals manage their energy balance.

growth and energy expenditure

When animals grow, their bodies need more energy and materials like proteins and minerals to form new tissues. This phase of life means their inputs (what they eat and drink) exceed their outputs (the energy they use up).

This happens because:

• New cells and tissues are constructed
• More energy is required to support developmental processes
• There’s an increase in body mass that needs sustenance

In growing animals, like young mammals or birds, it is typical for energy intake to surpass energy expenditure to support continuous growth and development.

homeostasis

Homeostasis is the process by which animals maintain a stable internal environment despite changes in external conditions. This regulation can affect temperature, pH levels, hydration, and nutrient balance. Homeostasis is crucial for survival and efficient functioning of the organism. It involves:

• Regulating internal temperature
• Maintaining balanced hydration levels
• Ensuring proper nutrient and energy levels

Although homeostasis strives for balance, it doesn't prevent increased energy and material intake during periods of growth or when recovering from illness or injury. These specific scenarios result in temporary imbalances where inputs exceed outputs.