SSCE VCE Biology Regulation of Plant and Animal Systems: Homeostasis is essential for the

Question

Homeostasis is essential for the survival of any organism.

**a. i. What is homeostasis?**

Homeostasis is the regulation of internal conditions within an organism to maintain a stable internal environment, despite changes in external conditions.

**a. ii. State one variable, other than body temperature and blood calcium levels, that is under homeostatic control in a mammal. Explain why the homeostatic control of this variable is essential for survival.**

Variable: Blood glucose

Explanation: Blood glucose levels are essential for cellular respiration, as glucose is the primary energy source for cells. If glucose levels are too low, it can lead to loss of energy, causing impaired cell function and, ultimately, organ failure. Conversely, excessively high glucose levels can cause damage to blood vessels and lead to conditions like diabetes.

The flow chart below summarises a sequence of events occurring inside a rod cell in the retina of the human eye.

**b. i. Explain why a rod cell is regarded as a receptor in this system.**

A rod cell is considered a receptor because it detects light stimuli and converts them into electrical impulses, allowing for vision in low light conditions.

**b. ii. Many of a human's regulating systems are based on negative feedback: Does the series of events taking place in a rod cell form part of a negative feedback system? Explain your answer.**

Yes, the series of events forms part of a negative feedback system. When light hits the rod cells, a series of biochemical reactions occurs, leading to hyperpolarization of the cell, which reduces the release of neurotransmitters. This change helps modulate the response to light, preventing overstimulation of the visual system and maintaining balance in sensory input.

Homeostasis is essential for the survival of any organism - VCE - SSCE Biology - Question 6 - 2012 - Paper 1

Worked Solution & Example Answer:Homeostasis is essential for the survival of any organism - VCE - SSCE Biology - Question 6 - 2012 - Paper 1

What is homeostasis?

State one variable, other than body temperature and blood calcium levels, that is under homeostatic control in a mammal. Explain why the homeostatic control of this variable is essential for survival.

Explain why a rod cell is regarded as a receptor in this system.

Many of a human's regulating systems are based on negative feedback: Does the series of events taking place in a rod cell form part of a negative feedback system? Explain your answer.

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