Biology EOC Second Semester

Which molecule would be found within the nucleus?

• mRNA

• tRNA

• DNA

Which molecule is able to go between the nucleus and ribosomes found within the cytoplasm?

• DNA

• mRNA

• tRNA

How does natural selection affect populations?

• By creating variation in individuals that allows them to better adapt to changing environmental conditions.

• By increasing the rate of beneficial mutations which allow individuals to increase their rate of reproduction.

• By reducing variation between individuals in a population thereby making the population more homogenous and likely to survive.

• By acting on variations between individuals that make some better adapted to their environment and more likely to survive and reproduce.

In most species, scientists have observed that related individuals share about 80% of the same genes. Cheetahs today, however, are known to share 99% of the same genes.

What does this lack of genetic diversity imply about the history of the cheetah population?

• Cheetahs never have experienced mutations.

• Cheetahs have experienced the bottleneck effect

• Cheetahs interbred with other large cat species.

• Cheetahs share a common ancestor with other large cat species.

The European corn borer is a pest whose larvae cause damage to corn crops in the United States. Pesticides can be used to control the larvae. As an alternative, scientists have developed a genetically engineered form of corn called the Bt strain. It produced a toxin in its cells called Bt, which is poisonous to the corn borer larvae. Farmers who plant fields of Bt corn are required by law to plant fields of non-Bt corn nearby as well.

Which statement explains why farmers would be required to plant non-Bt corn near the Bt corn?

• to provide controls for Bt toxin experiments with corn borers

• to keep corn borers from cross-pollinating Bt and non-Bt corn

• To slow reproductive selection for a Bt toxin-resistant corn borer

• To prevent movement of corn borers from Bt to non-Bt corn fields

In Labrador Retriever dogs, the black coat color allele (B) is dominant over the chocolate coat color allele (b). However, some litters produce dogs that have a yellow coat color. Scientists have determined this is because of a second gene that can influence coat color. If this eumelanin gene is recessive for both alleles (e), the dog's coat will be yellow regardless of the alleles for the other coat color gene.

A dog breeder sets up a cross between two dogs that are heterozygous for both coat color (Bb) and eumelanin (Ee).

What percentage of the dogs will be yellow?

• 56%

• 18%

• 25%

• 6%

Scientists collect data on the size and number of worms that three bird species prefer to eat. The feeding preference data of three bird species are shown.

Which statement is supported by the data?

• no competition for food exists within any of the three bird species

• at least three different species of worms are eaten by the three bird species

• selection pressure from the three bird species will result in a worm population with only small and large worms

• less competition between the three bird species will be observed if a range of differently sized worms is available.

Which statement describes crossing over as it occurs in meiosis?

• the alleles of a gene separate

• spindle fibers pull apart sist chromatids

• genes move to opposite ends of the chromosomes

• homologous chromosomes exchange segments of DNA

Which molecule was coded for by the longest piece of DNA?

• A protein with 25 amino acids

• A polysaccharide with 60 sugars

• An mRNA molecule with 20 codons

• An mRNA molecule with 45 nucleotides

• A

• B

• C

• D