AZSCI Stability and Change 1 — Questions and Answers
Question 1: The human body sweats when it gets too hot and shivers when it gets too cold. These responses are examples of the body trying to maintain a stable internal temperature. What is this process called?
- Metabolism
- Homeostasis (Correct answer)
- Evolution
- Respiration
Correct answer: Homeostasis
Homeostasis is the process by which biological systems maintain a stable internal environment despite changes in external conditions. Regulating body temperature is a classic example of a homeostatic mechanism.
Question 2: A forest ecosystem can remain relatively unchanged for hundreds of years. Which of the following would most likely disrupt the stability of this ecosystem and cause significant change?
- Seasonal changes in temperature and rainfall
- The introduction of an invasive insect species (Correct answer)
- The natural life and death cycles of its native trees
- A slight increase in the native deer population
Correct answer: The introduction of an invasive insect species
Introducing a non-native (invasive) species can drastically disrupt an ecosystem's stability. The new species may have no natural predators, outcompete native species for resources, and cause a cascade of changes throughout the food web.
Question 3: In a reversible chemical reaction, equilibrium is reached when...
- all of the reactants have been converted to products.
- the concentration of reactants equals the concentration of products.
- the rate of the forward reaction equals the rate of the reverse reaction. (Correct answer)
- the temperature of the system stops changing.
Correct answer: the rate of the forward reaction equals the rate of the reverse reaction.
Chemical equilibrium is a state of dynamic balance, not a state where the reaction has stopped. It is achieved when the rate at which reactants are forming products is exactly equal to the rate at which products are reverting to reactants. This results in no net change in the concentrations of substances.
Question 4: The rock cycle describes how rocks are continuously formed, broken down, and reformed into different types (igneous, sedimentary, metamorphic). This cycle is best described as a system in...
- a state of rapid, unpredictable change.
- a state of static, unchanging stability.
- a state of dynamic equilibrium over geologic time. (Correct answer)
- a process that is quickly coming to an end.
Correct answer: a state of dynamic equilibrium over geologic time.
The rock cycle represents a system that is constantly changing over vast geological timescales, yet it follows a predictable, cyclical pattern. This is a form of dynamic equilibrium, where change is constant but the overall system persists.
Question 5: The melting of Arctic sea ice exposes darker ocean water. This darker water absorbs more sunlight than the reflective ice, causing further warming and more ice to melt. This is an example of a:
- stabilizing system.
- negative feedback loop.
- positive feedback loop. (Correct answer)
- state of equilibrium.
Correct answer: positive feedback loop.
This is a positive feedback loop. An initial change (melting ice) causes an effect (more heat absorption) that amplifies the original change, leading to even more melting. Positive feedback loops drive systems away from stability.
Question 6: Newton's First Law of Motion states that an object at rest will stay at rest and an object in motion will stay in motion unless acted upon by an external force. This law describes a condition of:
- constant acceleration.
- stability or inertia. (Correct answer)
- gravitational change.
- chemical reaction.
Correct answer: stability or inertia.
Newton's First Law, also known as the law of inertia, describes the stability of an object's state of motion. An object's velocity (which includes speed and direction) will not change unless a net force acts on it. This is a fundamental principle of stability in physics.
Question 7: Over millions of years, the process of natural selection can lead to the evolution of new species. This represents a:
- rapid change within a stable system.
- short-term cycle of stability.
- gradual change in a system over a long timescale. (Correct answer)
- system that resists all forms of change.
Correct answer: gradual change in a system over a long timescale.
Evolution is a process of gradual change over very long periods. While individual organisms and populations are subject to forces that maintain stability (like stabilizing selection), the overall process of evolution is one of slow, directional change in response to environmental pressures.
AZSCI Stability and Change 1
The human body sweats when it gets too hot and shivers when it gets too cold.
These responses are examples of the body trying to maintain a stable internal temperature.
What is this process called?