Science 8 A Unit 3 Review

Which option explains why genes are sections of chromosomes, but chromosomes are not made up of genes?

• Genes are partly in chromosomes and partly in DNA.

• There are sections of chromosomes that are not genes.

• Genes are partly in chromosomes and partly in proteins.

• Each chromosome is its own, single gene.

Read the statement.

Scientists have discovered that under certain conditions, electrons have a probability of jumping through space and reappearing elsewhere.

Which example uses this probability to help reveal patterns?

• using this discovery to obtain additional resources for scientific research

• writing a science-fiction story that uses teleportation based on electrons jumping

• coming up with a physical model that would explain why electrons behave in this manner

• building a microscope that uses this principle to view objects as small as individual atoms

Read the statements.

In eukaryotic organisms, genes usually consist of two alleles. The two alleles are often on different parts of the same chromosome.

These sentences contain incorrect information. Which option describes the mistake?

• In eukaryotic organisms, the two alleles of the gene are on different chromosomes.

• In eukaryotic organisms, the two alleles of the gene are joined end to end on the same chromosome.

• In eukaryotic organisms, genes are usually spread over four or more chromosomes.

• In eukaryotic organisms, genes usually consist of a single allele.

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Which of Mendel’s discoveries had the most important role in leading scientists to understand DNA held the genetic code?

• The cross between a tall pea plant and a short pea plant always results in tall pea plants.

• Genes are made up of two alleles, and each allele comes from one parent.

• Some traits disappear in some generations and then reappear in future generations.

• Some genes are dominant over the others.

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Read the statements.

When Mendel first crossed a tall pea plant with a short pea plant, the offspring were always tall. When Mendel crossed the offspring with each other, the second-generation offspring had some short plants.

What conclusion can be drawn from this observation?

• The first-generation plants would also have short ones. Mendel did not do enough trials.

• There is a 25% chance that any second-generation plant will be tall.

• There is a 25% chance that any second-generation plant will be short.

• Short plants showed up every other generation in pea plants.

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