Question 1

Which of the following statements best explains why cellulose cannot be digested by humans, while starch can be?

Accepted Answer

The glycosidic linkages in cellulose are beta ($\beta$) linkages, which human enzymes cannot hydrolyze, while starch contains alpha ($\alpha$) linkages that can be digested.

Question 2

A dehydration reaction is crucial in the synthesis of biological polymers. Which of the following best describes what occurs during this reaction?

Accepted Answer

A water molecule is removed, forming a new covalent bond between two monomers.

Question 3

Which of the following molecules is NOT a true polymer?

Accepted Answer

Lipid

Question 4

A patient is diagnosed with a genetic disorder that alters the primary structure of hemoglobin. Which level of protein structure is directly affected first, and what is the likely consequence?

Accepted Answer

Primary structure; the sequence of amino acids is changed, potentially altering all higher levels of structure.

Question 5

Which of the following best explains why phospholipids form bilayers in aqueous environments?

Accepted Answer

Their hydrophobic tails avoid water, while their hydrophilic heads interact with water, causing self-assembly into bilayers.

Question 6

Which of the following is a correct description of the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have the maximum number of hydrogen atoms and no double bonds; unsaturated fatty acids have one or more double bonds.

Question 7

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes act as catalysts, speeding up chemical reactions without being consumed.

Question 8

A mutation causes a protein to lose its tertiary structure but retain its primary and secondary structures. Which of the following is most likely to occur?

Accepted Answer

The protein will lose its specific three-dimensional shape, likely resulting in loss of function.

Question 9

Which of the following statements about nucleic acids is correct?

Accepted Answer

A nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups.

Question 10

Which of the following best explains why trans fats are considered unhealthy compared to cis fats?

Accepted Answer

Trans fats have a straighter structure, allowing them to pack tightly and increase the risk of cardiovascular disease.

Question 11

Which of the following is a function of cholesterol in animal cells?

Accepted Answer

It is a component of cell membranes and a precursor for steroid synthesis.

Question 12

A scientist is studying a molecule with the formula $C_{6}H_{12}O_{6}$. Which class of biological molecule does this most likely represent, and what is its primary function?

Accepted Answer

A monosaccharide; serves as a quick energy source.

Question 13

Which of the following best describes the flow of genetic information in a cell?

Accepted Answer

$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$

Question 14

Which of the following is true about the structure of DNA?

Accepted Answer

The two strands run antiparallel and are held together by hydrogen bonds between complementary bases.

Question 15

Which of the following best explains why glycogen is an effective energy storage molecule in animals?

Accepted Answer

Glycogen is highly branched, allowing rapid release of glucose when energy is needed.

Question 16

A person is unable to produce the enzyme lactase, which breaks down lactose into glucose and galactose. Which type of reaction is impaired in this individual?

Accepted Answer

Hydrolysis reaction

Question 17

Which of the following is a correct pairing of a protein function and its example?

Accepted Answer

Enzymatic protein – Digestive enzyme catalyzing hydrolysis of food molecules

Question 18

Which of the following best describes the difference between a nucleotide and a nucleoside?

Accepted Answer

A nucleoside contains a nitrogenous base and a pentose sugar, while a nucleotide also contains one or more phosphate groups.

Question 19

Which of the following best explains why proteins can have such a wide variety of functions in cells?

Accepted Answer

The sequence and arrangement of 20 different amino acids allow for diverse structures and functions.

Question 20

Which of the following is a real-life example of a disease associated with protein misfolding?

Accepted Answer

Alzheimer’s disease

Structure and Function of Large Biological Molecules (Macromolecules)

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