Unit 2 Evolution

Why do some scientists believe that RNA, rather than DNA, was the first genetic material?

• a)RNA has both information storage and catalytic properties.
• RNA contains uracil in place of thymine
• RNA could have evolved into DNA.
• a)RNA can replicate more accurately than DNA. 

The conditions on early earth most likely______.

• Extremely cold temperatures
• Lack of water vapor in the air
• Presence of self-replicating molecules
• Very low levels of free oxygen

Why did scientists revise the classification of organisms into three domains?

• Analysis of genetic data from different organisms showed there were many conflicts with the five-kingdom system.
• Organisms were reclassified as autotrophs, heterotrophs, or decomposers, based on their method of obtaining energy.
• The kingdoms Monera and Protista were determined to be obsolete, and domains were created in an effort to simplify classification.
• Two kingdoms were eliminated when plants, animals, and fungi were combined to form one domain that includes only eukaryotes.

Why did scientists revise the classification of organisms into three domains?

• Analysis of genetic data from different organisms showed there were many conflicts with the five-kingdom system.
• Organisms were reclassified as autotrophs, heterotrophs, or decomposers, based on their method of obtaining energy.
• The kingdoms Monera and Protista were determined to be obsolete, and domains were created in an effort to simplify classification.
• Two kingdoms were eliminated when plants, animals, and fungi were combined to form one domain that includes only eukaryotes. 

In black birds, the allele for red eyes (r) is recessive to the allele for black eyes (R). A population that is in Hardy-Weinberg equilibrium has an allele frequency of r = 0.4. If there are 250 offspring in the next generation, which of the following would be expected? 

• 40 birds with red eyes and 210 birds with black eyes
• 62 birds with red eyes and 188 birds with black eyes
• 90 birds with red eyes and 160 birds with black eyes
• 100 birds with red eyes and 150 birds with black eyes

In black birds, the allele for red eyes (r) is recessive to the allele for black eyes (R). A population that is in Hardy-Weinberg equilibrium has an allele frequency of r = 0.4. If there are 250 offspring in the next generation, which of the following would be expected? 

• 40 birds with red eyes and 210 birds with black eyes
• 62 birds with red eyes and 188 birds with black eyes
• 90 birds with red eyes and 160 birds with black eyes
• 100 birds with red eyes and 150 birds with black eyes

Which of the following best compares the effects of artificial selection and gene flow on the genetic makeup of a population?

• Artificial selection and gene flow are both random, but artificial selection decreases genetic variation and gene flow increases it.
• Artificial selection and gene flow are both selective, but artificial selection increases genetic variation and gene flow decreases it.
• Artificial selection is random and increases genetic variation, while gene flow is selective and decreases it. 
• Artificial selection is selective and decreases genetic variation, while gene flow is random and increases it. 

An observable trait in a reptile species is determined by a single gene, for which there are only two alleles. The dominant allele, R, expresses complete dominance over the recessive allele, r. The table below shows the number of individuals over five generations with the dominant and recessive phenotypes. 

• Gene flow is causing r to increase in frequency. 
• Genetic drift is causing R to increase in frequency.
  
• The allele R is being selected against and is unstable in frequency. 
  
• The population is in Hardy-Weinberg equilibrium for this trait.
  

You discover three fossil organisms and want to determine their dates. You measure the percentage  of carbon-14 (half-life 5,730 years) remaining in the fossils. Which of the following correctly places them in order from oldest to youngest?

• A, B, C
  
• B, C, A
  
• C, A, B

If the mitochondria and chloroplasts in eukaryotic cells resulted from endosymbiosis, what feature(s) might we expect these organelles to contain?

• a plasma membrane, DNA, and ribosomes
  
• a plasma membrane, nucleus, and ribosomes
  
• nucleus, DNA, and ribosomes
  
• a plasma membrane, nucleus, and cilia