Question 1

Which of the following best describes the difference between a hypothesis and a scientific theory?

Accepted Answer

A hypothesis is a tentative explanation that can be tested, while a theory is a well-substantiated explanation supported by a large body of evidence.

Question 2

Which of the following statements about prokaryotic and eukaryotic cells is correct?

Accepted Answer

Eukaryotic cells have their genetic material enclosed within a nucleus, while prokaryotic cells do not.

Question 3

A neutral atom of sodium ($$^{23}\mathrm{Na}) $$has an atomic number of 11 and a mass number of 23. How many neutrons does it contain?

Accepted Answer

$$12$$

Question 4

Which of the following best explains why water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water molecules are polar, allowing them to surround and interact with charged and polar solutes.

Question 5

Which of the following statements about the structure of phospholipids and their role in biological membranes is correct?

Accepted Answer

Phospholipids have both hydrophilic and hydrophobic regions, allowing them to form bilayers in aqueous environments.

Question 6

A protein's tertiary structure is primarily stabilized by which of the following interactions?

Accepted Answer

Ionic, hydrophobic, and disulfide interactions between R-groups

Question 7

Which of the following best explains why cells are limited in size by their surface area-to-volume ratio?

Accepted Answer

As a cell grows, its volume increases faster than its surface area, limiting the rate of exchange of materials with the environment.

Question 8

Which of the following processes requires energy input in the form of ATP to move substances across the cell membrane?

Accepted Answer

Active transport

Question 9

Which of the following equations correctly represents the change in free energy ($$\Delta G) $$for a chemical reaction?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 10

During cellular respiration, which stage produces the most ATP?

Accepted Answer

Oxidative phosphorylation (electron transport chain and chemiosmosis)

Question 11

Which of the following best describes the role of the promoter in transcription?

Accepted Answer

It is the region where RNA polymerase binds to initiate transcription.

Question 12

A point mutation changes the codon $$UAC ($$tyrosine) to $$UAA ($$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 13

In a dihybrid cross between two heterozygous pea plants ($$YyRr 	imes YyRr$$), what is the probability of obtaining an offspring with the genotype $$yyrr$$?

Accepted Answer

$$\dfrac{1}{16}$$

Question 14

Which of the following mechanisms does NOT contribute to genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during S phase

Question 15

Which of the following statements about X-linked inheritance is correct?

Accepted Answer

Males are more likely to express X-linked recessive traits because they have only one X chromosome.

Question 16

Which of the following best describes the difference between complete dominance, incomplete dominance, and codominance?

Accepted Answer

In complete dominance, one allele completely masks the other; in incomplete dominance, the phenotype is intermediate; in codominance, both alleles are fully expressed.

Question 17

Which of the following best explains why an insertion or deletion mutation is more likely to be harmful than a substitution mutation?

Accepted Answer

Insertions and deletions can cause frameshift mutations, altering the reading frame of the gene.

Question 18

Which of the following is a correct description of the process of translation?

Accepted Answer

tRNA molecules bring amino acids to the ribosome, where the sequence of codons in mRNA determines the order of amino acids in the polypeptide.

Question 19

Which of the following best describes the law of independent assortment?

Accepted Answer

Alleles for different genes assort independently of one another during gamete formation.

Question 20

Which of the following is true regarding the structure of DNA and RNA nucleotides?

Accepted Answer

Both DNA and RNA nucleotides contain a phosphate group, a five-carbon sugar, and a nitrogenous base.

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