Why is cellulose so difficult for most animals to digest?
1. they don’t have the proper enzyme to break the bonds between subunits
2. cellulose is made up of chitin, which is indigestible
3. the bonds holding cellulose subunits together are extremely strong, stronger than in any other macromolecule
4. there are many hydrogen bonds holding the subunits together

Catalytic efficiency of two different enzymes is compared by their :
1. Product
2. Molecular size
3. Km value
4. pH optimum value

Which statement regarding enzyme inhibition is correct?
1. Competitive inhibition occurs when a substrate competes with enzyme for binding to inhibitor protein
2. Competitive inhibition occurs when a substrate and the inhibitor compete for active site on the enzyme
3. Non-competitive inhibition of an enzyme can be overcome by adding a large amount of substrate
4. Non-competitive inhibitors often bind to the enzyme irreversibly

Cell membrane carbohydrates participate in
1. transporting substances between two protein layers
2. cell-to-cell recognition
3. attaching the membrane to cytoskeleton
4. cell adhesions

Carbohydrates are commonly found as starch in plant storage organs. Which of the following five properties of starch (a-e) make it useful as a storage material?
(i). easily translocated
(ii). chemically non-reactive
(iii). easily digested by animals
(iv). osmotically inactive
(v). synthesized during photosynthesis
The useful properties are:

A molecule of ATP is structurally most similar to :
1. RNA nucleotide
2. DNA nucleotide
3. amino acid
4. fatty acid

In feedback inhibition, a metabolic pathway is switched off by:
1. a rise in temperature
2. lack of a substrate
3. accumulation of the end product
4. competitive inhibition

The unique properties of each amino acid is determined by its particular :
1. R group
2. amino group
3. kinds of peptide bonds
4. number of bonds to other amino acids

In competitive inhibition, if the concentration of the substrate is increased :
1. the rate of the reaction is increased
2. the rate of the reaction is decreased
3. the rate of the reaction is not affected
4. the reaction direction is reversed

Identify the structure of the amino acid that is a Zwitter ion :

1.		2.
3.		4.