New York State Chemistry RegentsNew York State Earth Science Regents

Heredity and Genetics
Living Environment Regents June 2004 Question 01 PDF Print E-mail


Correct Answer: (2) contain identical genes

Cloning is the process of making a lineage of genetically identical individuals. This naturally occurs in bacteria, plants and some insects that reproduce asexually.

Incorrect Answers:

Clones have the same genotype. Appearance and behavior are usually affected by the environment (phenotype) and thus, it is not necessary that clones would have identical appearance and behavior.

Mutation is the change in the DNA sequence of an individual. Since clones have identical DNA, mutation is absent.

Enzymes are proteins which are produced by the dictation of the genes. Clones have the same genes, then same enzymes will be formed.

Living Environment Regents June 2004 Question 02 PDF Print E-mail


Correct Answer: (2) A theory is an assumption made by scientists and implies a lack of certainty.

Theory is an idea or explanation which has not yet been proved to be correct. According to the gene-chromosome theory, genes are segments of DNA positioned on chromosomes in homologous pairs. This theory is not yet proven, however, it is used as an assumption in studying genetics.

Living Environment Regents June 2004 Question 04 PDF Print E-mail


Correct Answer: (3) Genes are found on chromosomes. Chromosomes are found in nuclei.

Nucleus (plural, nuclei) is the chromosome-containing organelle of a eukaryotic cell. Chromosome is a thread-like association of genes in the nucleus of all eukaryotic cells and most visible during mitosis and meiosis. Chromosomes consist of DNA and protein. Gene is one of the many discrete hereditary information located on the chromosomes and consisting of DNA.

Living Environment Regents June 2004 Question 08 PDF Print E-mail


Correct Answer: (3) The expression of gene A varies with the environment.

The expression of gene A was affected by light. When the organism with gene A was exposed to light, the final appearance was green. On the other hand, when it was in the dark, the final appearance was white.

Incorrect Answers:

Based on the table, the expression of gene B was not affected by the environmental condition. Whether the organism with gene B was exposed to light or darkness, the final appearances were the same.

Living Environment Regents June 2004 Question 09 PDF Print E-mail


Correct Answer: (1) a sequence of paired bases

DNA is composed of nitrogenous bases paired by hydrogen bonds. These bases have specific pairing system, wherein Adenine and Thymine can only bond with each other, while Cytosine and Guanine pair with each other.

Living Environment Regents June 2004 Question 10 PDF Print E-mail


Correct Answer: (2) different parts of an individual's DNA are used to direct the synthesis of different proteins in different types of cells.

The DNA contains codons that code for amino acids to be produces during translation or protein synthesis. During cell differentiation, the proteins formed will form into different cells with particular structure based on their functions.

Incorrect Answer:

Mutation is the change in the DNA sequence. Formation of different cells is not always caused by mutation. The difference of structure and function of beta and acinar cells are due to different expression of genes during cell differentiation.

Homeostasis refers to the body's mechanism to maintain a stable and constant environment.

Both genes for acinar and beta cells are contributed by the same parents. During fertilization, the genes of the parents are combined.
Living Environment Regents June 2004 Question 26 PDF Print E-mail


Correct Answer: (1) Interbreeding between members of the population increased the mutation rate.

One of the conditions of faster mutation rate is the large number of interbreeding organisms in the population. The variation reached its stable state, and thus, the population became stabilized.

Incorrect Answers:

Since there was less competition, then there was no scarcity of food and other resources.

Based on the graph, the population size neither decreased not increased, but it became stabilized at a certain level.

Living Environment Regents June 2004 Question 34 PDF Print E-mail


Correct Answer: (4) blocking the expression of a gene that helps the colonies to organize.

When this is successfully accomplished, the colonies formed will be weak and can easily be washed away by the use of detergent.

Incorrect Answers:

Antibiotics and detergents were not useful for the impediment of biofilm production, as well as cutting the tubes.

Living Environment Regents June 2004 Question 35 PDF Print E-mail


Correct Answer: (1) cellular communication

A neuron is a nerve cell and is the fundamental unit of the nervous system. It has structures and properties that allow conduction of signals by taking advantage of the electrical change across its cell membrane.

Living Environment Regents June 2004 Question 39 PDF Print E-mail


Correct Answer: (1) human insulin

Insulin was previously harvested from animals with similar insulin characteristics. However, these insulin produced by animals causes production of antibodies in the human body. Thus, scientist produced human insulin by injecting an insulin gene to a bacterial vector (E. coli).

Incorrect Answers:

Antibodies are proteins produced by the body that recognize foreign or harmful materials in the body. These are not produced by the bacterial cell injected with insulin gene.

Enzymes are proteins that speed up various metabolic processes of the body. They are also not produced by E. coli injected with insulin gene.

Insulin production was necessary for humans who have low insulin levels, especially who have a disease called diabetes mellitus. Therefore, the insulin needed must be the same with the insulin produced by the human body.

Living Environment Regents June 2004 Question 50 PDF Print E-mail


Correct Answer: (3) Val-Glu-Phe-Asp-Asp-Thr

The letters A, C,T, and G represent the nitrogenous bases found in the DNA. A stands for adenine, C stands for cytosine, T for thymine and G for guanine. A group of three nucleotides codes for an amino acid. Therefore, the following amino acid sequence woul be produced in the given DNA base sequence:

CAA   GGT    AAA   TTA    TTG    TGA

Val      Glu     Phe     Asp     Asp     Thr

Living Environment Regents June 2004 Question 51 PDF Print E-mail


Correct Answer: mutation

Mutation refers to any change in the DNA sequence. An agent that causes mutation is called a mutagen. Mutagens include high energy radiation, chemicals, and even high temperatures. There are four known types of chromosomal mutations: deletion, insertion, inversion or translocation.

Living Environment Regents June 2004 Question 52 PDF Print E-mail


This is called a point mutation. The mutated DNA would have an amino acid threonine instead of proline. The error my or may not interfere with the protein function.

Living Environment Regents June 2004 Question 61 PDF Print E-mail


Correct Answer: Bear 1 and 3 are most closely related.

The bands represent the rate of movement of the DNA fragments depending on their molecular weights. Since the DNA samples of Bears 1 and 3 reached the negative end at the same rate, they are most closely related.

Living Environment Regents June 2004 Question 62 PDF Print E-mail


Biometric identification system can also be used to identify the common traits and possible evolutionary linkages between the bears.

Living Environment Regents June 2004 Question 63 PDF Print E-mail


Correct Answer: (1) size

Agarose gel electrophoresis is a method used to separate DNA or RNA molecules by size. The negatively charged nucleic acid molecules move through an agarose matrix with an electric field (electrophoresis).


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