(9-12) A1

Science Curriculum Preview Committee Clarification of Learning Results

Revised 04/07/04

9-12

A1: Explain the role of DNA in resolving questions of relationship and evolutionary change.

Curriculum Organizing Questions

Why is DNA important to a cell?

Why is DNA important to a species?

Where do you find identical DNA?

Where do you find similarities in DNA?

Where do you find differences in DNA?

What do major similarities or differences in DNA indicate?

How can organisms that look very different have similar DNA?

How is DNA used to resolve disputes about relationship?

How do scientists use DNA to study evolution of organisms?

What do scientists look for when they study DNA?

How has modern use of DNA substantiated evidence for evolution?

Elaboration
The variety of earth's life forms is apparent not only from the study of anatomical and behavioral similarities and differences among organisms, but also from the study of similarities and differences among their molecules. SFAA pgs. 60-61. Students should take their study to the molecular level and learn that it is possible to infer relatedness among organisms from DNA or protein sequences, and that the DNA code is virtually the same for all life forms. Benchmarks p. 105. Knowledge of DNA contributes to the evidence for life having evolved from common ancestors and provides a plausible mechanism for the origin of new traits.Benchmarks p.124. Molecular evidence substantiates the anatomical evidence from fossils and provides additional detail about the sequence in which various lines of descent branched off from one another.Benchmarks 5F2.

Learning transcription and translation are not necessary for achieving this standard.

Specific Ideas

In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA. NSES C2a.

All cells of a single organism have essentially identical DNA.

There are similarities in DNA observed among diverse species of living organisms.

The degree of kinship between organisms for species can be estimated from the similarity of their DNA sequences. Benchmarks 5A2.

DNA sequences often match classification of organisms that is based on anatomical similarities. Benchmarks 5A2.

DNA provides for the continuity of species as well as the variation that in time can lead to differences within a species and to entirely new species. Benchmarks pg.108.

The millions of different species of organism that live on earth today are related by descent from common ancestors. NSES C3d.

DNA evidence substantiates the anatomical evidence for evolution and provides additional detail about the sequence in which various lines of descent branched off from one another. Benchmarks 5F2.

Developmental & Instructional Implications
The idea of mutation needs to be carefully developed. Many students think that mutations can be intentional, or can happen within an individual's life time (to its benefit). The idea that a mutation must be present in the sex cells in order to be passed on tends to be poorly understood.

An inquiry based approach is suggested.

Modern ideas of evolution provide a scientific explanation for three main sets of observable facts about life on earth: the enormous number of different life forms, we see about us, the systematic similarities in anatomy and molecular chemistry we see in that diversity, and the sequence of changes in fossils found in successive layers of rock that have been formed over more than a billion years. Because molecular biology will continue into the twenty-first century as a major frontier of science, students should understand the chemical basis of life not only for its own sake, but because of the need to take informed positions on some of the practical and ethical implications of humankind's capacity to manipulate living organisms. Benchmarks 5F7.

Examples

Back to Big Ideas Grid A Back to Standard A Back to Index

Curriculum Organizing Questions	Why is DNA important to a cell? Why is DNA important to a species? Where do you find identical DNA? Where do you find similarities in DNA? Where do you find differences in DNA? What do major similarities or differences in DNA indicate? How can organisms that look very different have similar DNA? How is DNA used to resolve disputes about relationship? How do scientists use DNA to study evolution of organisms? What do scientists look for when they study DNA? How has modern use of DNA substantiated evidence for evolution?
Elaboration	The variety of earth's life forms is apparent not only from the study of anatomical and behavioral similarities and differences among organisms, but also from the study of similarities and differences among their molecules. SFAA pgs. 60-61. Students should take their study to the molecular level and learn that it is possible to infer relatedness among organisms from DNA or protein sequences, and that the DNA code is virtually the same for all life forms. Benchmarks p. 105. Knowledge of DNA contributes to the evidence for life having evolved from common ancestors and provides a plausible mechanism for the origin of new traits.Benchmarks p.124. Molecular evidence substantiates the anatomical evidence from fossils and provides additional detail about the sequence in which various lines of descent branched off from one another.Benchmarks 5F2. Learning transcription and translation are not necessary for achieving this standard.
Specific Ideas	In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA. NSES C2a. All cells of a single organism have essentially identical DNA. There are similarities in DNA observed among diverse species of living organisms. The degree of kinship between organisms for species can be estimated from the similarity of their DNA sequences. Benchmarks 5A2. DNA sequences often match classification of organisms that is based on anatomical similarities. Benchmarks 5A2. DNA provides for the continuity of species as well as the variation that in time can lead to differences within a species and to entirely new species. Benchmarks pg.108. The millions of different species of organism that live on earth today are related by descent from common ancestors. NSES C3d. DNA evidence substantiates the anatomical evidence for evolution and provides additional detail about the sequence in which various lines of descent branched off from one another. Benchmarks 5F2.
Developmental & Instructional Implications	The idea of mutation needs to be carefully developed. Many students think that mutations can be intentional, or can happen within an individual's life time (to its benefit). The idea that a mutation must be present in the sex cells in order to be passed on tends to be poorly understood. An inquiry based approach is suggested. Modern ideas of evolution provide a scientific explanation for three main sets of observable facts about life on earth: the enormous number of different life forms, we see about us, the systematic similarities in anatomy and molecular chemistry we see in that diversity, and the sequence of changes in fossils found in successive layers of rock that have been formed over more than a billion years. Because molecular biology will continue into the twenty-first century as a major frontier of science, students should understand the chemical basis of life not only for its own sake, but because of the need to take informed positions on some of the practical and ethical implications of humankind's capacity to manipulate living organisms. Benchmarks 5F7.
Examples