Grade-9 ASP Quiz-2

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This question refers to the following data in which the fatty acid composition of membrane phospholipids was analyzed in plants growing at two different temperatures.

Which of the following is true according to the data above?

• The saturation of fatty acids in phospholipids increases and decreases at increased temperatures.

• At higher temperatures, plants increase membrane fluidity by decreasing the saturation and increasing the chain length of the fatty acids in their phospholipids.

• The proportion of unsaturated fatty acids in membrane phospholipids decreases at higher temperatures.

• Increasing fatty acid saturation and chain length occur at both higher and lower temperatures.

The table lists the 20 amino acids that make up proteins organized by the chemical reactivity of their side chains. Which of the following statements correctly identifies the purpose of categorizing amino acids by the chemical nature of their side chains?

• The properties of a protein are a function of the shape of the protein that is determined by the composition of nonpolar amino acids.

• The chemistry of an amino acid determines which other amino acids it can form a peptide bond with, affecting the order of the amino acids in the proteins.

• The side chains of the amino acids determine the structure of a protein by determining the sequence of amino acids in the polypeptide.

• The function of a protein is mostly predictable by the side chain chemistry of the amino acids.

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The amino acid in Figure 1 is found in a region of a polypeptide that turns away from water. Which part of the amino acid most likely contributes to its hydrophobic behavior?

Amine (NH2) group Carboxyl (COOH) group Methyl (CH3) group Hydrogen (H) atom

• Amine (NH2) group

• Carboxyl (COOH) group

• Methyl (CH3) group

• Hydrogen (H) atom