UNIT 9 Review

A television is a device that converts electrical energy into light and sound energy. However, this energy transformation is not 100% efficient.

What happens to the electrical energy that enters a television but is not converted into light or sound?

• It returns to the electrical socket to create new energy.

• It is transformed into heat energy.

Answer explanation

The electrical energy that is not converted into light or sound in a television is transformed into heat energy. This is a common byproduct of energy conversion processes, indicating inefficiency.

Student researching a northern forest ecosystem learns the following information about feeding relationships in the ecosystem.

Which food web best represents the flow of energy in these feeding relationships?

• 
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Observe the illustration of a simple circuit below.

Which of the following statements best describes the energy transformation that takes place in this circuit?

• Electrical to chemical to mechanical to light (radiant) energy.

• Mechanical to chemical to electrical to light (radiant) energy.

Answer explanation

The correct choice, 'Mechanical to chemical to electrical to light (radiant) energy,' describes the energy transformation accurately. Mechanical energy initiates the process, converting to chemical energy, then to electrical energy, and finally to light energy.

Naima loves using her battery-powered toothbrush in the mornings.  It makes her teeth feel so fresh and clean. 

Which of the following describes the energy transformations taking place within her toothbrush?

• Chemical→ Mechanical → Electrical and Sound

• Chemical → Electrical → Mechanical and Sound

Answer explanation

The correct choice is Chemical → Electrical → Mechanical and Sound. The toothbrush converts chemical energy from its battery into electrical energy, which then powers the mechanical movement of the brush, producing sound.

After researching the diets of several birds inhabiting a nearby pond, a student goes on a field investigation to observe the feeding habits of the birds. The student records information from research and observations in the table.

Based on the information the student collected, which two species of bird will most likely compete for the same limiting factors?

• Great Blue Heron and Great Egret

• Great Blue Heron and Pied-billed Grebe

Answer explanation

The Great Blue Heron and Pied-billed Grebe both feed on similar aquatic prey, making them likely competitors for food resources in the pond, while the Great Egret has different feeding habits.

A partial food web is shown.

The numbers in the boxes represent animals in the food web.

 

Which of the following statements best explains the process of energy transfer in the food web?

• Organism 3 is a primary consumer of organisms 5 and 7 because they receive energy from plants only.

• Organism 6 could be a decomposer that receives its energy from breaking down the remains of organism 7.

Answer explanation

Organism 6 is correctly identified as a decomposer, as it obtains energy by breaking down the remains of organism 7, illustrating the vital role of decomposers in recycling energy within the food web.

Caleb is riding his bicycle. He works very hard to reach the top of a hill and then coasts down the other side.

Which statement best explains what happens as Caleb rides down the hill?

• Chemical energy is transformed into mechanical and thermal energy and the total amount of energy is conserved during the entire bike ride.

• Chemical energy is transformed into mechanical and thermal energy and the total amount of energy decreases at the bottom of the hill.

Answer explanation

As Caleb rides down the hill, his chemical energy from pedaling is converted into mechanical energy (motion) and thermal energy (friction). The total energy remains constant, demonstrating the conservation of energy throughout the ride.

Mangrove trees are common to the Florida Everglades. The tree roots serve as a place for freshwater oysters to attach when the tide is high, as shown in the picture below. The oysters are protected from predators when attached to the roots underwater.

The oysters do not harm the trees, nor do they provide any benefit to the trees. Which of the following relationships is most similar to the relationship between the mangrove trees and the oysters?

• Mutualism - Spider crabs are camouflaged by the green-brown algae growing on their shells.

• Commensalism - A whale is unaffected by the attached remora fish feeding on the whale’s leftover food.

Answer explanation

The relationship between mangrove trees and oysters is similar to commensalism, where one species benefits without affecting the other. The remora fish feed on leftover food from whales without harming them, just like oysters on mangroves.

Which of the statements below is the best comparison of the symbiotic relationships described above?

• Relationship A is mutualism and relationship B is predation.

• Relationship A is mutualism and relationship B is parasitism.

Answer explanation

Relationship A is mutualism, where both species benefit, while relationship B is parasitism, where one species benefits at the expense of the other. This distinction clarifies why the correct choice is that A is mutualism and B is parasitism.

Which of the following statements is the best description of what happens to a population when a resource that is a limiting factor in the environment suddenly becomes scarce?

   

• The population size will decrease to a size that can be supported by that limiting factor.

• The population size will increase until that limiting factor becomes abundant again.

Answer explanation

When a limiting resource becomes scarce, the population cannot be sustained at its previous size. Therefore, it will decrease to a level that can be supported by the available resources.