3.6.4.1 Principles of homeostasis and negative feedback

What is homeostasis in mammals primarily responsible for?

• Maintaining external environmental conditions

• Maintaining the internal environment within restricted limits

• Increasing metabolic rate

• Enhancing physical strength

Answer explanation

Homeostasis in mammals is primarily responsible for maintaining the internal environment within restricted limits, ensuring stable conditions for bodily functions despite external changes.

Why is maintaining a stable core temperature important for enzyme activity?

• It prevents enzymes from becoming too active

• It ensures enzymes do not denature

• It increases enzyme production

• It decreases enzyme efficiency

Answer explanation

Maintaining a stable core temperature is crucial because it ensures enzymes do not denature. High temperatures can disrupt the enzyme's structure, leading to loss of function, while optimal temperatures promote proper activity.

How does a stable blood pH affect enzyme activity?

• It allows enzymes to function optimally

• It causes enzymes to become inactive

• It reduces enzyme concentration

• It increases enzyme degradation

Answer explanation

A stable blood pH is crucial for enzyme activity, as it allows enzymes to maintain their optimal shape and function. Deviations in pH can lead to reduced activity or inactivation, making the correct choice "It allows enzymes to function optimally."

What is the significance of maintaining a stable blood glucose concentration?

• It prevents dehydration

• It ensures a constant supply of respiratory substrate

• It increases blood pressure

• It decreases metabolic rate

Answer explanation

Maintaining stable blood glucose levels is crucial as it ensures a constant supply of respiratory substrate, which is essential for energy production in cells. This prevents energy deficits that can impair bodily functions.

How does blood glucose concentration affect the water potential of blood?

• High glucose concentration increases water potential

• Low glucose concentration decreases water potential

• High glucose concentration decreases water potential

• Glucose concentration has no effect on water potential

Answer explanation

High glucose concentration decreases water potential because glucose is a solute that increases osmotic pressure, leading to a lower water potential in the blood.

What role does negative feedback play in homeostasis?

• It amplifies changes in the system

• It restores systems to their original level

• It disrupts homeostatic balance

• It prevents any changes in the system

Answer explanation

Negative feedback is crucial in homeostasis as it helps restore systems to their original level after a change occurs, maintaining balance and stability within the body.

Why is it beneficial for organisms to have separate mechanisms for negative feedback?

• It allows for faster responses

• It provides a greater degree of control

• It reduces energy consumption

• It simplifies the regulatory process

Answer explanation

Having separate mechanisms for negative feedback provides a greater degree of control, allowing organisms to fine-tune their responses to various stimuli and maintain homeostasis more effectively.

What happens to enzymes if the core temperature of a mammal is too high?

• Enzymes become more efficient

• Enzymes denature and lose function

• Enzymes replicate faster

• Enzymes become inactive temporarily

Answer explanation

If a mammal's core temperature is too high, enzymes denature, meaning they lose their specific structure and function. This disrupts metabolic processes, making 'Enzymes denature and lose function' the correct answer.

Which of the following is a consequence of unstable blood pH?

• Enhanced enzyme activity

• Enzyme denaturation

• Increased oxygen transport

• Improved metabolic rate

Answer explanation

Unstable blood pH can lead to enzyme denaturation, which disrupts their structure and function. This negatively impacts metabolic processes, unlike enhanced activity or improved rates, which require stable pH levels.

What is the primary function of glucose in the blood?

• To act as a structural component

• To serve as a respiratory substrate

• To regulate blood pressure

• To transport oxygen

Answer explanation

The primary function of glucose in the blood is to serve as a respiratory substrate, providing energy for cellular processes through metabolism. It is not a structural component, nor does it regulate blood pressure or transport oxygen.