
	Item 44 Anchor Papers

HSA 2007 Biology Item 44

CID: CIDe72a333470e886607b2e46ca25bc1bda
itemNum: 44
initialLetter
itemType: BCR
itemAnswerKey: N/A
itemMaxScorePoints: 4
origNum: x

Marine and land iguanas are two different species that inhabit the Galapagos Islands. Some scientists believe that both species diverged from a common ancestor. Marine iguanas eat algae. Land iguanas feed on cacti. Algae are more abundant in the ocean than cacti are on the islands. Both species lay their eggs in the sand.

Rats, cats, and goats have recently been introduced to the islands. Rats often feed on iguana eggs, cats eat baby iguanas, and goats eat cacti.

Explain how the two species of iguanas could have developed from a common ancestor. In your response, be sure to

name the process that explains how marine and land iguanas developed from a common ancestor
describe the steps involved in this process
explain how the introduction of rats, cats, and goats might affect both iguana species

Write your answer in your Answer Book.

Score Level 1 Anchor Paper
This response demonstrates some understanding of the question. The process is correctly identified (natural selection). Though not a definition of natural selection, the description does refer to reproduction (gametes randomly combine). No information beyond that given in the prompt is provided for the effects on the iguana population. The supporting details are only minimally effective.
Score Level 1 Anchor Paper
This response demonstrates some understanding of the question. The process is identified (evolution). A few steps in the process are listed (migrates; adapts to new environments). The effects of cats, rats, and goats are briefly listed (result in a decrease of population; land iguanas will have competition for food). The supporting details are only minimally effective.
Score Level 2 Anchor Paper
This response demonstrates a basic understanding of the question. The process is identified (Natural selection). Some possible steps are discussed (a group of iguanas were seperate from the other iguana because of a natural disaster; iguanas would begin to change & adapt to the new environment). The effects of rats, cats, and goats are explained (rats would eat both species eggs, decreasing potential population; the goat would eat much of the main food source for the land iguanas; Decreasing their population). Overall, the supporting details are adequate.
Score Level 2 Anchor Paper
This response demonstrates a basic understanding of the question. The process is identified (natural selection). Some steps of the process are outlined sequentially in a chart (population growth; scarcity; competition; adaptation; accumulation). The effects of rats, cats, and goats on both species are addressed (they could feed on them; scarcity of mates and the population would not grow). Overall, the supporting details are adequate.
Score Level 3 Anchor Paper
This response demonstrates a good understanding of the question. The process is identified (natural selection). Several details are provided about the steps of the process (food was scarce; adapations on the limbs to help the marine iguanas move more effectively; teeth would gradually change; iguanas that are not very well adapted to the ocean gradually die out; gene pool that produces these slight adapations more and more frequent). The discussion of the effects of rats, cats, and goats demonstrates synthesis and includes a common effect on both species (the rats and cats feed on the eggs and young iguanas of both species) and an effect unique to each (the goats would diminish their food supply [cacti] but not the algae). Overall, the supporting details are generally complete.
Score Level 3 Anchor Paper
This response demonstrates a good understanding of the question. The process is identified (evolution). The description of the process includes steps at the cellular level (random mutation in DNA), adaptation (became better adapted to live in a different environment), and reproduction (passing on the mutated gene to its offspring). Synthesis is demonstrated in the description of the effects of rats and cats on both iguana species (they eat the offspring … This will hurt the populations of both species). The more severe impact on land iguanas is described (their food source, cacti, is being eaten by goat; it is likely this species will die out). Terminology strengthens the response (random mutation).
Score Level 4 Anchor Paper
This response demonstrates a full and complete understanding of the question. The process is identified (Through the process of natural selection the species split; iguanas evolved into what they are today). The student uses pertinent and complete supporting details that demonstrate an integration of ideas as the steps in the process are tied in to how the two species could have developed from a common ancestor (natural adaptation that allowed it to digest alge better; the iguana reproduced and created a new species; Survival of the fittest allowed the iguanas to reproduce more offspring so the trait that allowed the iguana to digest algae got passed down from generation to generation). Synthesis of information is demonstrated by relating evolution of iguanas to the effect of cats and rats (through the process of natural selection and survival of the fittest, the fastest and most elusive baby iguanas will survive and evolve). Synthesis continues with the effects due to goats (less food for the iguanas to eat; iguanas that can survive with the least amount of food have a better chance of reproducing). Terminology enhances the response (natural adaptation; trait; survival of the fittest).

Anchor Papers ~ Biology ~ Item 44

HSA 2007 Biology Item 44

CID: CIDe72a333470e886607b2e46ca25bc1bda
itemNum: 44
initialLetter
itemType: BCR
itemAnswerKey: N/A
itemMaxScorePoints: 4
origNum: x

Rats, cats, and goats have recently been introduced to the islands. Rats often feed on iguana eggs, cats eat baby iguanas, and goats eat cacti.

Explain how the two species of iguanas could have developed from a common ancestor. In your response, be sure to

name the process that explains how marine and land iguanas developed from a common ancestor
describe the steps involved in this process
explain how the introduction of rats, cats, and goats might affect both iguana species

Write your answer in your Answer Book.

Score Level 1 Anchor Paper
This response demonstrates some understanding of the question. The process is correctly identified (natural selection). Though not a definition of natural selection, the description does refer to reproduction (gametes randomly combine). No information beyond that given in the prompt is provided for the effects on the iguana population. The supporting details are only minimally effective.

Score Level 1 Anchor Paper
This response demonstrates some understanding of the question. The process is identified (evolution). A few steps in the process are listed (migrates; adapts to new environments). The effects of cats, rats, and goats are briefly listed (result in a decrease of population; land iguanas will have competition for food). The supporting details are only minimally effective.

Score Level 2 Anchor Paper

This response demonstrates a basic understanding of the question. The process is identified (Natural selection). Some possible steps are discussed (a group of iguanas were seperate from the other iguana because of a natural disaster; iguanas would begin to change & adapt to the new environment). The effects of rats, cats, and goats are explained (rats would eat both species eggs, decreasing potential population; the goat would eat much of the main food source for the land iguanas; Decreasing their population). Overall, the supporting details are adequate.

Score Level 2 Anchor Paper

This response demonstrates a basic understanding of the question. The process is identified (natural selection). Some steps of the process are outlined sequentially in a chart (population growth; scarcity; competition; adaptation; accumulation). The effects of rats, cats, and goats on both species are addressed (they could feed on them; scarcity of mates and the population would not grow). Overall, the supporting details are adequate.

Score Level 3 Anchor Paper

This response demonstrates a good understanding of the question. The process is identified (natural selection). Several details are provided about the steps of the process (food was scarce; adapations on the limbs to help the marine iguanas move more effectively; teeth would gradually change; iguanas that are not very well adapted to the ocean gradually die out; gene pool that produces these slight adapations more and more frequent). The discussion of the effects of rats, cats, and goats demonstrates synthesis and includes a common effect on both species (the rats and cats feed on the eggs and young iguanas of both species) and an effect unique to each (the goats would diminish their food supply [cacti] but not the algae). Overall, the supporting details are generally complete.

Score Level 3 Anchor Paper

This response demonstrates a good understanding of the question. The process is identified (evolution). The description of the process includes steps at the cellular level (random mutation in DNA), adaptation (became better adapted to live in a different environment), and reproduction (passing on the mutated gene to its offspring). Synthesis is demonstrated in the description of the effects of rats and cats on both iguana species (they eat the offspring … This will hurt the populations of both species). The more severe impact on land iguanas is described (their food source, cacti, is being eaten by goat; it is likely this species will die out). Terminology strengthens the response (random mutation).

Score Level 4 Anchor Paper

This response demonstrates a full and complete understanding of the question. The process is identified (Through the process of natural selection the species split; iguanas evolved into what they are today). The student uses pertinent and complete supporting details that demonstrate an integration of ideas as the steps in the process are tied in to how the two species could have developed from a common ancestor (natural adaptation that allowed it to digest alge better; the iguana reproduced and created a new species; Survival of the fittest allowed the iguanas to reproduce more offspring so the trait that allowed the iguana to digest algae got passed down from generation to generation). Synthesis of information is demonstrated by relating evolution of iguanas to the effect of cats and rats (through the process of natural selection and survival of the fittest, the fastest and most elusive baby iguanas will survive and evolve). Synthesis continues with the effects due to goats (less food for the iguanas to eat; iguanas that can survive with the least amount of food have a better chance of reproducing). Terminology enhances the response (natural adaptation; trait; survival of the fittest).