Ecosystem Stability SCA Review

What is the relationship shown in the image?

• Predation

• Commensalism

• Competition

• Parasitism

• Mutualism

Answer explanation

The image likely depicts organisms vying for the same resources, indicating competition. In competition, both species are negatively affected as they struggle to obtain limited resources, distinguishing it from other relationships.

In phloem flows _______

• food (glucose)

• water (H₂0)

Answer explanation

In phloem, food in the form of glucose is transported from the leaves to other parts of the plant. This process is essential for providing energy and nutrients, making 'food (glucose)' the correct answer.

Fire ants have a powerful venom that is deadly to the small animals they eat. The deadly venom has reduced the populations of birds that build nests on the ground.

The relationship between fire ants and ground-nesting birds is an example of:

• producer/consumer

• predator/prey

• scavenger/decomposer

• parasite/host

Answer explanation

The relationship between fire ants and ground-nesting birds is predator/prey, as fire ants (predators) use their venom to kill small animals, including birds (prey), affecting their populations.

Mistletoe extracts water and nutrients from the spruce tree to the detriment (ill effect) of the spruce. This is an example of which type of symbiosis?

• parasitism

• commensalism

• mutualism

• predation

Answer explanation

Mistletoe extracts resources from the spruce tree, harming it in the process. This relationship is an example of parasitism, where one organism benefits at the expense of another.

The two types of vascular tissue in plants are the _____________ and the _________________?

• bark, wood

• ground, dermal

• roots, stem

• phloem, xylem

Answer explanation

The two types of vascular tissue in plants are phloem and xylem. Phloem transports nutrients, while xylem carries water and minerals, making them essential for plant growth and function.

A young tree was hit by a lawn mower that scraped off a large section of bark all the way through to the wood. Within a few days, leaves on several of the branches began to die. What is the most likely cause of the leaves dying?

• The leaves were diseased already, and they died coincidentally when the bark was injured.

• The wood was weakened by the injury and could no longer support the weight of the branches above it.

• The bark contained the xylem and phloem tubes and, once they were damaged, they could no longer produce glucose to feed the leaves.

• The vascular tissue under the bark was damaged and could no longer transport water and nutrients to the leaves.

Answer explanation

The bark injury damaged the vascular tissue, preventing the transport of water and nutrients to the leaves. Without these essential resources, the leaves began to die.

Analyze the positions of the plants and the animals in the food web pictured above. What type of impact could occur if there were a sudden decrease in the snake population?

• There would be a decrease in the number of shrews, rabbits, and mountain lions.

• There will be an increase in the number of rabbits and shrews.

• There will be a decrease in the number of cacti and sagebrush plants.

• The mountain lion population will increase.

Answer explanation

If the snake population decreases, their prey, such as rabbits and shrews, would have less predation pressure. This would likely lead to an increase in the populations of rabbits and shrews, as they would thrive without snakes.

What is the relationship shown in the image?

• Predation

• Commensalism

• Competition

• Parasitism

• Mutualism

Answer explanation

The image likely depicts a predator-prey relationship, where one organism (the predator) hunts and consumes another (the prey). This is characteristic of predation, making it the correct choice.

How do changes in one population in a food web affect other populations?

• Changes in one population can only affect other populations if they are closely related genetically.

• Changes in one population can affect other populations through direct and indirect interactions in the food web as this can affect the flow of energy in ecosystems.

• Changes in one population only affect the population directly above it in the food web.

• Changes in one population have no impact on other populations.

Answer explanation

Changes in one population can impact others in a food web through direct and indirect interactions, influencing energy flow and ecosystem dynamics. This highlights the interconnectedness of species within the ecosystem.

Cattle egrets are birds that live near large grazing animals. They feed on insects that are exposed as the grazing animals walk through grass. A scientist theorizes that these species could eventually develop a mutualistic relationship. Which of the following situations, if observed, would support this scientist's theory?

• Cattle are not affected by cattle egrets.

• Cattle are seen feeding on cattle egrets.

• Cattle egrets begin to eat ticks living on cattle.

• Cattle egrets begin to draw nutrients from cattle.

Answer explanation

Cattle egrets eating ticks on cattle would indicate a mutualistic relationship, as the egrets benefit from food while helping the cattle by reducing parasites. This supports the scientist's theory of mutualism.