BIO practice exam 2

The genetic code is redundant or degenerate because each amino acid can be coded by multiple codons.

True

When Friedich Meischer isolated cells from the pus containing bandages, what did he observe the "nuclein" were rich in?

phosphorus

The following is the order in which translation proceeds:

1. mRNA binds to the small ribosomal subunit and the initiator tRNA binds to the start codon. 

2. The next tRNA binds to the A site and a peptide bond is formed between the two amino acids.

3. The mRNA shifts the tRNA in the P site to the E site, causing it to leave the ribosome. 

4. Upon encountering a stop codon, the release factor aids in the hydrolysis of the newly synthesized polypeptide from the ribosome. 

True

Which of the following is TRUE for cells in the G₀ phase of the cell cycle?

The cells are not actively dividing.5

In organisms that are not actively growing or reproducing, mitosis is still required for activities like wound healing and tissue renewal.

True

Results for question 6.

6

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A centriole is the constricted point where sister chromatids are attached to each other. 

Correct answer:

False

Results for question 7.

7

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Which of the following describes a karyotype?

Correct answer:

It is an image of an individual's complete collection of chromosomes.

IResults for question 8.

8

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During DNA replication, the leading strand needs one RNA primer and the lagging strand needs several RNA primers.

Correct answer:

True

Results for question 9.

9

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During DNA replication, which enzyme is responsible for relieving torsional stress caused by the unwinding of the DNA double helix?

Correct answer:

Topoisomerase

Results for question 10.

10

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Which organelle is involved in the formation of spindle fibers during mitosis?

Correct answer:

Centrosome

Results for question 11.

11

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In a double-stranded DNA, the strand that is being transcribed by RNA polymerase is called the ___________ and it has a sequence ____________ to the mRNA strand being synthesized.

Correct answer:

template; complementary

Results for question 12.

12

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In humans, mitosis results in the production of genetically __________ and ___________ somatic cells.

Correct answer:

identical; diploid

Results for question 13.

13

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During post-transcriptional processing in eukaryotes, which of the following is added to the 3' end of the mRNA?

Correct answer:

poly-A tail

Results for question 14.

14

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Ribosomes are often attached to which organelle so that newly synthesized polypeptides can easily enter that organelle for post-translational modifications?

Correct answer:

Endoplasmic reticulum (ER)

0.25 / 0.25 points

In eukaryotes transcription and translation are spatially separated and do not occur simultaneously.

Correct answer:

True

Which stage of DNA packaging is referred to as "beads on a string" structure?

Correct answer:

10nm

Results for question 17.

17

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Which organism did Frederick Griffith use in his experiments that showed transformation in bacteria?

Correct answer:

Streptococcus pneumoniae

Results for question 18.

18

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Which of the following organisms require the protein FtsZ during binary fission?

Correct answer:

Prokaryotes

Results for question 19.

19

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There are 3 checkpoints in cell cycle regulation. Which checkpoint checks if spindle fibers are attached to the kinetochore of sister chromatids? 

Correct answer:

M checkpoint

Results for question 20.

20

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In 1958, Meselson and Stahl showed that DNA replication follows the _____________ model.

Correct answer:

Semi-conservative

Results for question 21.

21

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DNA replication takes place during G₂ phase of Interphase during the cell cycle.

Correct answer:

False

Results for question 22.

22

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Which of the following is involved in the splicing of introns and joining of exons into a functional mRNA?

Correct answer:

Spliceosome

Results for question 23.

23

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The following is the order in which mRNA is synthesized:

1. RNA Polymerase once bound to the promoter with the help of transcription factors, initiates mRNA synthesis at the start of the template strand.

2. RNA Polymerase continues to elongate the mRNA strand reading the template strand as the DNA helix keeps unwinding. 

3. mRNA transcript is released upon transcription termination.

4. In eukaryotes, this nascent mRNA the undergoes post-transcriptional processing. 

Correct answer:

True

Results for question 24.

24

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The "one gene one enzyme" hypothesis by Beadle and Tatum is still accurate to date and has never been modified. 

Correct answer:

False

During mitosis, in which phase does the nuclear envelope start breaking down?

Correct Answer:

Prophase

Results for question 26.

26

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How many chromosomes does a normal diploid human cell have?

Correct answer:

23 pairs

Results for question 27.

27

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DNA Polymerase can add new nucleotides to which end of the growing DNA strand?

Correct answer:

3' end

Results for question 28.

28

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Which of the following is NOT true for ribosomes?

Correct answer:

They are essential for mRNA synthesis.

Results for question 29.

29

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DNA that is accessible for gene expression is called ____________, whereas __________ is inaccessible for gene expression.

Correct answer:

euchromatin; heterochromatin

Results for question 30.

30

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During DNA replication, which enzyme is responsible for joining the Okazaki fragments to form the completed lagging strand?

Correct answer:

DNA ligase

Results for question 31.

31

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Which of the following enzymes is required for polymerase chain reaction (PCR)?

Correct Answer:

DNA polymerase

Results for question 32.

32

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DNA is synthesized in the 5' -> 3' direction, whereas RNA is synthesized in the 3' -> 5' direction.

Correct answer:

False

Results for question 33.

33

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Which is the first amino acid in every polypeptide synthesis during translation?

Correct answer:

Methionine

Results for question 34.

34

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Which enzyme is responsible for preventing gene erosion and delay cellular aging in the process?

Correct answer:

Telomerase

Results for question 35.

35

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HeLa cells make an immortal cell line, which were ethically obtained from Henrietta Lacks.

Correct Answer:

False

Results for question 36.

36

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mRNA is read as a template for protein synthesis in the form of __________, each of which is made of _______ nucleotides.

Correct Answer:

codons; 3

Results for question 37.

37

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Which of the following was shown in "Photo 51", a work by the famous Rosalind Franklin?

Correct answer:

The helical structure of DNA

Results for question 38.

38

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During cytokinesis, a cleavage furrow is formed to separate the cytoplasm in both plant and animal cells.

Correct answer:

False

Results for question 39.

39

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Beadle and Tatum worked with Neurospora crassa to show the "one gene one enzyme" hypothesis. Which nutrients were missing in the minimal medium that they used to grow this organism?

Correct Answer:

Vitamins only

Results for question 40.

40

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___________ protein develops in the centromeric region during ____________ of mitosis, which are then involved in the attachment of spindle fibers to the sister chromatids.

Correct answer:

Kinetochore; prometaphase