Life at a Molecular Level

Which are true about DNA and RNA?

i Both of them contain ribulose sugar.

ii Their monomers are nucleosides.

iii Their nitrogenous bases are purines and pyrimidines.

iv Their sugar phosphate backbones are maintained by phosphodiester bonds.

• i and ii

• i and iv

• ii and iii

• iii and iv

Which of the following is the correct example of protein denaturation?

• A protein is exposed to extremely high heat, causing it to lose its secondary structure and be left with only its primary structure.

• A protein binds with a substrate, lowering the activation energy of a reaction.

• Amino acids fold into repeating patterns due to hydrogen bonding of the peptide backbone.

• Several amino acids are joined together via peptide bonds.

A DNA template strand contains the following sequence:

5′ AGGCTCCAG 3′

Which complementary RNA strand can be made from this sequence?

• 5′ GACCTCGGA 3′

• 5′ UCCGAGGUC 3′

• 5′ CUGGAGCCU 3′

• 5′ UGGCTCCUG 3′

Tags

NGSS.HS-LS3-1

Polypeptides are chains of amino acids linked together in a specific order.

What type of bonds are formed between these amino acids?

• Glycosidic linkage

• Phosphoester bond

• Ester linkage

• Peptide bond

The percentage of thymine (T) in a given segment of double-stranded DNA is 36%.

What are the percentages of the remaining nucleotides?

• 36% U, 14% C, 14% G

• 36% A, 14% C, 14% G

• 14% A, 36% C, 14% G

• 14% A, 14% C, 36% G

How are triglycerides formed?

• Triglycerides are formed through condensation, which results in the addition of H₂O molecules.

• Triglycerides are formed through hydrolysis, which results in the production of H₂O molecules.

• Triglycerides are formed through condensation synthesis, which results in the loss of H₂O molecules.

• Triglycerides are formed through hydrolysis, which results in the loss of H₂O molecules.

A(n) ____________ is a basic unit of a carbohydrate.

• Amino acid

• Disaccharide

• Monosaccharide

• Glycerol

A polysaccharide that makes plant cells and tissues structurally rigid is:

• Amylopectin

• Starch

• Glycogen

• Cellulose

The structure of the protein is shown in the diagram above.

Which product will be produced after the protein is organised?

• Keratin

• Protease

• Haemoglobin

• Collagen

Which property of water enables it to act as a biological lubricant?

• Water has a low viscosity

• Water has a high surface tension

• Water is a liquid at room temperature

• Water is a polar molecule