Question

Two Biology problems

Please answer all of these with details otherwise please 'do not answer any'

A. The figure above shows two types of carbohydrates commonly found in plants. Which of the following is a correct statement about these carbohydrates? a. A is an energy storage polysaccharide because its beta-glycosidic linkages are more resistant to hydrolysis. b. B is a structural polysaccharide because its beta-glycosidic linkages are more easily hydrolyzed. c. B is an energy storage polysaccharide because its alpha-glycosidic linkages are more easily hydrolyzed. d. A is a structural monosaccharide because its alpha-glycosidic linkages are more resistant to hydrolysis. e. Both A and B are correct statements. The correct answer is C: B is an energy storage polysaccharide because its alpha-glycosidic linkages are more easily hydrolyzed. Why is this answer correct? Because alpha-glycosidic linkages are a type of peptide bond that holds together the higher-level structure of all types of complex carbohydrates. Because alpha-glycosidic linkages are more likely to result in branches for higher-level structures which provide more space for water/enzymes to access them. Because beta-glycosidic linkages are broken down by condensation reactions rather than the hydrolysis reaction as is noted in the answer. Because alpha-glycosidic linkages store less energy than beta-glycosidic linkages which means that hydrolysis will proceed more easily. O Because even though beta-glycosidic linkages are common in energy storage polysaccharides, this specific one uses alpha-glycosidic linkages as an exception to the rule.

Answer 1

ANS 3 A is cellulose and B is starch

the correct is ans is option (B)

As you can see, the bends in alpha linkages will curve the molecules enough that stablization by hydrogen bonding is much less significant. Since the bonds are therefore more accessible to hydrolytic enzymes, the covalent linkages between monomers are more easily broken.

The basis for the answer is the "bends" in alpha linkages vs the "straightness" of beta linkages, and the resulting effect on stabilization of the molecules by hydrogen bonding with their neighbors. Cellulose, with its beta linkages, is fully "extended" because the alternating glucose molecules are at 180 degree turns to each other. This allows very easy hydrogen bonding, not only between monomers in the same fibril, but also with neighboring fibrils, making the entire structure much more stable and resistant to hydrolysis by, for example, digestive enzymes. This is why most animals like us cannot digest cellulose. Starch/glycogen, on the other hand, are composed of alpha linkages, which cause each glycosidic linkage to bend slightly.

O CH2OH (814)-linked D-glucose units CH2OH НО, HO 9 110 (a 1-4)-linked D-glucose units

As you can see, the bends in alpha linkages will curve the molecules enough that stablization by hydrogen bonding is much less significant. Since the bonds are therefore more accessible to hydrolytic enzymes, the covalent linkages between monomers are more easily broken. So you're right, a covalent bond is a covalent bond. But at the level of the biochemistry, different types of linkages have a significant role on the stability of the resulting polysaccharide.

ANS 4. (D)

These attractions are an example of hydrogen bonds, weak interactions that form between a hydrogen with a partial positive charge and a more electronegative atom, such as oxygen. The hydrogen atoms involved in hydrogen bonding must be attached to electronegative atoms, such as O\text{O}Ostart text, O, end text, N\text{N}Nstart text, N, end text, or F\text{F}Fstart text, F, end text.

polar covalent bond (H) St S. hydrogen bond

Water molecules forming hydrogen bonds with one another. The partial negative charge on the O of one molecule can form a hydrogen bond with the partial positive charge on the hydrogens of other molecules.

Water molecules are also attracted to other polar molecules and to ions. A charged or polar substance that interacts with and dissolves in water is said to be hydrophilic: hydro means "water," and philic means "loving." In contrast, nonpolar molecules like oils and fats do not interact well with water. They separate from it rather than dissolve in it and are called hydrophobic: phobic means "fearing." You may have noticed this as a not-so-handy feature of oil and vinegar salad dressings. Vinegar is basically just water with a bit of acid.