Topic 7 - Keystone Sample Quiz

1. Although all of the cells of a human develop from one fertilized egg, the human is born with many different types of cells. Which statement best explains this observation?

Developing cells may express different parts of their identical genetic instructions.

Different chromosomes are present in each cell.

Mutations occur during development as a result of environmental conditions.

Some cells develop before other cells.

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Explanation

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2. The flounder is a species of fish that can live in very cold water. The fish produces an "antifreeze" protein that prevents ice crystals from forming in its blood. The DNA for this protein has been identified. An enzyme is used to cut and remove this section of flounder DNA that is then spliced into the DNA of a strawberry plant. As a result, the plant can now produce a protein that makes it more resistant to the damaging effects of frost. This process is known as

Sorting of genes

Genetic engineering

Recombination of chromosomes

Mutation by deletion of genetic material

The process described involves manipulating the DNA of the strawberry plant by inserting a section of flounder DNA that codes for an antifreeze protein. This manipulation of genetic material to introduce new traits into an organism is known as genetic engineering. It allows for the transfer of genes between different species to confer desired characteristics, in this case, making the strawberry plant more resistant to frost damage.

Explanation

The process described involves manipulating the DNA of the strawberry plant by inserting a section of flounder DNA that codes for an antifreeze protein. This manipulation of genetic material to introduce new traits into an organism is known as genetic engineering. It allows for the transfer of genes between different species to confer desired characteristics, in this case, making the strawberry plant more resistant to frost damage.

3. Which process will increase variations that could be inherited?

Mitotic cell division

Active transport

Recombination of genes

Synthesis of proteins

Recombination of genes is the process that increases variations that could be inherited. During recombination, genetic material from two different parental sources is exchanged, leading to the creation of new combinations of genes. This process introduces genetic diversity into the population, as it allows for the mixing and shuffling of genetic information. In contrast, mitotic cell division, active transport, and synthesis of proteins do not directly contribute to increasing variations that could be inherited.

Explanation

Recombination of genes is the process that increases variations that could be inherited. During recombination, genetic material from two different parental sources is exchanged, leading to the creation of new combinations of genes. This process introduces genetic diversity into the population, as it allows for the mixing and shuffling of genetic information. In contrast, mitotic cell division, active transport, and synthesis of proteins do not directly contribute to increasing variations that could be inherited.

4. Young birds that have been raised in isolation from members of their species build nests characteristic of their species. This suggests that the nest-building behavior is

A disadvantage to the survival of the species

Learned by watching members of their species

Genetically inherited from parents

A direct result of the type of food the bird eats

The fact that young birds raised in isolation from members of their species still build nests characteristic of their species suggests that nest-building behavior is genetically inherited from parents. This implies that the ability to build nests is passed down through genes rather than being learned by watching other birds.

Explanation

The fact that young birds raised in isolation from members of their species still build nests characteristic of their species suggests that nest-building behavior is genetically inherited from parents. This implies that the ability to build nests is passed down through genes rather than being learned by watching other birds.

5. For centuries, certain animals have been crossed to produce offspring that have desirable qualities. Dogs have been mated to produce Labradors, beagles, and poodles. All of these dogs look and behave very differently from one another. This technique of producing organisms with specific qualities is known as

Gene replication

Natural selection

Random mutation

Selective breeding

The technique described in the passage involves intentionally mating animals with specific desired qualities in order to produce offspring with those same qualities. This process is known as selective breeding, as it involves selecting certain individuals to breed based on the traits they possess. This is different from gene replication, which refers to the process of DNA being copied to create new cells, and random mutation, which refers to spontaneous changes in genetic material. Natural selection is a process in which organisms with advantageous traits are more likely to survive and reproduce, but it is not the same as the intentional breeding described in the passage.

Explanation

The technique described in the passage involves intentionally mating animals with specific desired qualities in order to produce offspring with those same qualities. This process is known as selective breeding, as it involves selecting certain individuals to breed based on the traits they possess. This is different from gene replication, which refers to the process of DNA being copied to create new cells, and random mutation, which refers to spontaneous changes in genetic material. Natural selection is a process in which organisms with advantageous traits are more likely to survive and reproduce, but it is not the same as the intentional breeding described in the passage.

6. A chemical known as 5-bromouracil causes a mutation that results in the mismatching of molecular bases in DNA. The offspring of organisms exposed to 5-bromouracil can have mismatched DNA if the mutation occurs in

The skin cells of the mother

The gametes of either parent

All the body cells of both parents

Only the nerve cells of the father

The correct answer is that the offspring of organisms exposed to 5-bromouracil can have mismatched DNA if the mutation occurs in the gametes of either parent. This is because gametes are the reproductive cells that combine during fertilization to form the offspring. Any mutation in the DNA of the gametes can be passed on to the offspring and result in mismatched bases in their DNA.

Explanation

The correct answer is that the offspring of organisms exposed to 5-bromouracil can have mismatched DNA if the mutation occurs in the gametes of either parent. This is because gametes are the reproductive cells that combine during fertilization to form the offspring. Any mutation in the DNA of the gametes can be passed on to the offspring and result in mismatched bases in their DNA.

7. The diagram below shows a normal gene sequence and three mutated sequences of a segment of DNA. Which row in the chart below correctly identifies the cause of each type of mutation?

1

2

3

4

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Explanation

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8. Which diagram best represents the relative locations of the structures in the list below? A–chromosome B–nucleus C–cell D–gene

1

2

3

4

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Explanation

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9. Even though identical twins have the same genetic material, they may develop slightly different characteristics because

Each twin receives different chromosomes from the egg

One twin may only have genes from the father

Gene expression may be influenced by factors that switch genes on and off

A gene mutation may have occurred before the zygote divided

Identical twins have the same genetic material because they originate from the same fertilized egg. However, they may develop slightly different characteristics because gene expression can be influenced by various factors that switch genes on and off. These factors can include environmental influences, lifestyle choices, and epigenetic modifications. Therefore, even though twins have the same genes, their gene expression can differ, leading to variations in their physical and behavioral traits.

Explanation

Identical twins have the same genetic material because they originate from the same fertilized egg. However, they may develop slightly different characteristics because gene expression can be influenced by various factors that switch genes on and off. These factors can include environmental influences, lifestyle choices, and epigenetic modifications. Therefore, even though twins have the same genes, their gene expression can differ, leading to variations in their physical and behavioral traits.

10. At warm temperatures, a certain bread mold can often be seen growing on bread as a dark-colored mass. The same bread mold growing on bread in a cooler environment is red in color. Which statement most accurately describes why this change in the color of the bread mold occurs?

Gene expression can be modified by interactions with the environment.

Every organism has a different set of coded instructions.

The DNA was altered in response to an environmental condition.

There is no replication of genetic material in the cooler environment.

The change in color of the bread mold from dark-colored to red in a cooler environment suggests that gene expression can be modified by interactions with the environment. This means that the environmental conditions, such as temperature, can influence how genes are expressed and result in observable changes in the organism's characteristics, such as color. The other options, such as every organism having a different set of coded instructions or the DNA being altered in response to an environmental condition, do not specifically explain the observed change in color. The option stating that there is no replication of genetic material in the cooler environment is unrelated to the color change.

Explanation

The change in color of the bread mold from dark-colored to red in a cooler environment suggests that gene expression can be modified by interactions with the environment. This means that the environmental conditions, such as temperature, can influence how genes are expressed and result in observable changes in the organism's characteristics, such as color. The other options, such as every organism having a different set of coded instructions or the DNA being altered in response to an environmental condition, do not specifically explain the observed change in color. The option stating that there is no replication of genetic material in the cooler environment is unrelated to the color change.