Quiz

QUIZ

1. In the Punnett square analysis of two parents that each have a dominant (T) allele and recessive (t) allele: what is the ratio of dominant to recessive phenotypes of offspring having the trait?

a. 1:2 b. 3:1 c. 1:3 d. 1:2

Answer: b. The ratio of dominant to recessive traits is 3:1 when using the Punnett square with three times as many dominant traits as recessive traits seen in the offspring.

2. In the Punnett square analysis of two parents that have a dominant T allele and a recessive t allele, what is the ratio of homozygous dominant to homozygous recessive genotypes in the offspring?

a. 1:1 b. 3:1 c. 1:3 d. 1:2

Answer: a. The ratio of homozygous dominant and homozygous recessive traits is 1:1 with the entire ratio of all genotypes being 1:2:1, with the ratio representing homozygous dominant: 2 heterozygous: homozygous recessive.

3. What is it called when a trait is equally expressed in the offspring of the male and female animal?

a. Autosomal dominant b. Codominance c. X-linked recessive d. Autosomal recessive

Answer: b. Codominance involves the equal expression in the offspring of alleles because an allele for the trait is neither dominant nor recessive but is considered codominant.

4. The parent who is homozygous for a dominant trait will pass the trait onto what percentage of their children on average?

a. 25 percent b. 50 percent c. 75 percent d. 100 percent

Answer: d. A total of 100 percent of the children of a parent with a homozygous dominant trait will get the trait. This is because they have no other allele to pass on to their offspring other than a dominant trait.

5. What type of chemical bond connects the sugar backbone in the DNA molecule?

a. Hydrogen bond b. Phosphodiester bond c. Hydroxyl bond d. Ester bond

Answer: b. There is a phosphodiester bond that links the sugars forming a sugar-phosphate-sugar bond between the 5-prime and the 3prime end of the adjoining deoxyribose sugars.

6. What aspect of chromatin most allows for the tight packaging of DNA into their tightly-wound structures?

a. Hydrogen bonding b. Double helix c. Histone proteins d. Chromosomes

Answer: c. While chromatin uses each of these features to shrink the size of the DNA molecule so it fits inside the cell nucleus, it is the

histone proteins that most allow for the folding and coiling of the DNA into the structure called chromatin.

7. Where in the cell does RNA polymerase function?

a. Ribosome b. Cytoplasm c. Endoplasmic reticulum d. Nucleus

Answer: d. RNA polymerase creates new RNA molecules from a DNA template gene. It operates in the nucleus where the DNA is located.

8. In prokaryotes, the genes are often located in operons. What is an operon?

a. A piece of DNA that codes for several proteins b. Areas of noncoding DNA c. Areas of regulatory genes along with introns d. Areas of DNA that code for pre-messenger RNA

Answer: a. An operon is a piece of DNA in prokaryotes that codes for several, often related, proteins.

9. About how many protein-coding genes are there in the human genome?

a. 2000 b. 6000

c. 20,000 d. 200,000

Answer: c. There are about 20,000 coding genes in the human genome, which represents about 1-2 percent of the total genome.

10. Where does most gene expression happen?

a. Post-translational modification b. Regulation of messenger RNA substance c. Translational stage of protein synthesis d. Transcription of DNA

Answer: d. Most gene expression happens at the transcriptional level, changing which genes get transcribed to RNA and which genes do not get transcribed.