Question

1. which of these is the best explanation for why the meniscus of water in the capillary is convex? (1.1)

a. the adhesive forces are stronger than the cohesive forces.
b. the cohesive forces are stronger than the adhesive forces.
c. the surface tension of the water is causing water molecules to be drawn down.
d. water has formed polar covalent bonds with the capillary tube walls causing attracted to the walls of the capillary tube than with other water molecules.

1. collagen is a structural protein found in connective tissues such as skin, tendons composed of three polypeptide chains wound together in a triple helix. the gene polypeptide chains of collagen, col1a1, is on chromosome 17 in humans. mut result in changes in the amino acid sequence of the resulting collagen protein. if an amino acid deletion in the sequence of amino acids that make up one of the c affect the structure of collagen? (1.4, 1.5)

a. only the primary structure of collagen will be affected; the secondary and tert affected.
b. both the primary structure and secondary structure of collagen will be affecte not be affected.
c. the primary, secondary, and tertiary structures of collagen will be affected.
d. an amino acid deletion would not affect the structure of collagen.

1. what is the key structural difference between rna and dna? (1.6)

a. dna contains ribose sugar, while rna contains deoxyribose sugar.
b. rna contains thymine, while dna contains uracil.
c. dna is typically double - stranded, while rna is typically single - stranded.
d. rna is composed of amino acids, while dna is composed of nucleotides.

1. you are given a protein with the following amino acid sequence: methionine (nonpolar)-glycine (nonpolar)-serine (polar)-alanine (nonpolar)

if an amino acid substitution occurred in this polypeptide chain, predict which o significant impact on the structure and function of the protein. (1.5)
a. serine is replaced by tryptophan (nonpolar).
b. glycine is replaced by alanine (nonpolar).
c. alanine is replaced by leucine (nonpolar).
d. lysine is replaced by arginine (polar).
nitrogen is an important element in building both: (1.2)
proteins and lipids
nucleic acids and lipids
proteins and nucleic acids
carbohydrates and proteins

Explanation:

1. When the cohesive forces between water - water molecules are stronger than the adhesive forces between water and the capillary - tube walls, the meniscus of water is convex. For option a, if adhesive forces are stronger, the meniscus is concave. Option c, surface tension alone doesn't explain the convex meniscus in this context. Option d, polar covalent bonds with the walls would lead to stronger adhesion and a concave meniscus.
2. A change in the amino - acid sequence (such as an amino - acid deletion) affects the primary structure. Since the secondary and tertiary structures are determined by the primary structure, they will also be affected.
3. The key structural difference between DNA and RNA is that DNA is typically double - stranded while RNA is typically single - stranded. Option a has the sugar types reversed. Option b has the nitrogenous bases reversed (RNA has uracil instead of thymine in DNA). Option d has the composition of proteins and nucleic acids confused.
4. Serine is a polar amino acid. Replacing it with a non - polar tryptophan can significantly change the protein's structure and function due to changes in hydrophobic and hydrophilic interactions within the protein.

Answer:

1. b
2. c
3. c
4. a