1. Practice Questions Day 2: Ecosystem stability and Changes
1) Surtsey is an island located south of Iceland. The island was formed by a volcanic eruption and first appeared in The table below contains descriptions of changes in the population and diversity of species on Surtsey.
Which of these lists the descriptions in the correct order of ecological succession on Surtsey?
A. I, II, IV, III B. IV, III, I, II
C. III, I, II, IV D. II, IV, I, III D (R)
2) The diagram shows the flow of organic molecules through an ecosystem. One process that occurs in this ecosystem is labeled X, and another process that occurs is labeled Y.
Which two processes are identified by the labels X and Y?
A. X: Respiration
Y: Predation
B. X: Adaptation
Y: Decomposition
C. X: Fermentation
Y: Nitrogen fixation
D. X: Decomposition
Y: Respiration
12E (S)
3) As ecosystems move through the stages of succession, the populations of organisms in them change. Which of the following describes the stage of succession likely to have the most species diversity?
A. A newly formed volcanic island
B. An agricultural field that has not been plowed for one year
C. A temperate forest that has never been cleared by logging
D. A field that is regularly mowed
11D (R)
4) Dead zones are low-oxygen areas that develop on the seafloor. Scientists hypothesize that phytoplankton blooms cause these dead zones. Phytoplankton blooms occur when excess nutrients are introduced by pollution from fertilizers, sewage plants, and the burning of fossil fuels. Which of the following would most likely cause an increase in these contributors to dead zones?
A. Rainfall patterns that increase freshwater runoff from terrestrial ecosystems
B. Replacing coal-fired power plants with windmills
C. Farming practices that reduce nitrate and phosphate applications
D. Constructing efficient water-recovery and treatment plants
12D (S)/
12F (R)

2. 5) In recent years humans have interfered with the natural balance within deer populations in various ecosystems. The interference includes eliminating predators of the deer. Which of the following statements correctly describes the long-term outcome of this interference?
F The deer that are the fastest and most agile will survive and reproduce.
G The deer population will be too large to be supported by producers.
H Other browsing species will thrive and outcompete the deer.
J The producers will evolve into species that are less palatable to the deer.
12D (S)
6) The mimosa plant displays thigmotropism by collapsing its leaves in response to touch, as shown in the pictures below. The plant on the left is undisturbed. The upper stem of the plant on the right has been touched.
What is the most likely benefit of this mechanism for the plant?
A. Protection from a loss of minerals to the environment
B. Protection from poor light availability
C. Protection from herbivores by becoming less attractive
D. Protection from overwatering
11B (S)
7) Hydrothermal vents form deep in the ocean when iron-rich magma is released from openings on the seafloor. These vents spew extremely hot water (400°C) mixed with methane and sulfur. Bacteria that thrive in this hostile environment form the base of a food chain that leads to colonization by tube worms, mussels, and many other life-forms. When a hydrothermal vent becomes inactive and cold, the bacterial community that lives in the hot fluid methane and sulfur dies out. Which organisms most likely succeed the original community in this ecosystem?
A. Cold-tolerant bacteria that feed on sulfur and iron in the vents
B. Giant kelp that use sulfur in photosynthesis
C. Fish that do not need oxygen for cellular respiration
D. Ocean mammals that tolerate cold and act as top predators in the food chain
12F (R)
8) The graph shows the basic changes in a forest community
after a disturbance occurred.
The information shown in the graph suggests that the changes in the forest community were caused by —
A. tree-leaf replacement after a storm
B. repeated habitat destruction
C. succession after a fire
D. decreased species diversity
11D (R)