IB Unit 2: Molecular Biology

B. Fatty acid

What substance is represented by this structure? A. Glycerol B. Fatty acid C. Cellulose D. Glycogen

D. Hydrogen

What type of bond is labeled X? A. Ionic B. Peptide C. Covalent D. Hydrogen

D. Polar amino acids

A channel protein is used to transport ions across a membrane. What would you expect to find lining the inside of the channel? A. Phospholipids B. Non-polar amino acids C. Fatty acids D. Polar amino acids

C. It is polar and therefore hydrophilic

Glucose is absorbed through protein channels in the plasma membrane of epithelium cells in the small intestine. What characteristics of glucose prevent its diffusion through the phospholipid bilayer? A. It is non-polar and therefore hydrophobic B. Its hydrogen bonds link with amino acids in the protein channel C. It is polar and therefore hydrophilic D. Its covalent bonds interact with the phospholipids

B. Immobilized

It is possible to attach ß-galactosidase to alginate beads for use in the production of lactose-free milk. What are enzymes that have been attached in this way called? A. Inhibited B. Immobilized C. Catalysed D. Activated

B. mRNA

On which molecule is a codon found? A. DNA B. mRNA C. tRNA D. rRNA

B. It has a very low proportion of oxygen to carbon

What characteristic shows that this steroid molecule is a lipid? A. It is made of carbon rings B. It has a very low proportion of oxygen to carbon C. It contains OH groups as do fatty acids D. It is made only of nitrogen, oxygen and hydrogen

A. Less energy is needed to warm water vapor than liquid water

What is a consequence of the specific heat capacity for liquid water, ice, and water vapor? A. Less energy is needed to warm water vapor than liquid water B. Salt dissolves more readily in liquid water than in ice C. Small insects can walk on liquid water D. Ice floats on liquid water

D. The structure of enzymes is determined by DNA

What is the relationship between enzymes and DNA? A. Enzymes contain the code for DNA B. Enzymes act on DNA during translation C. Both enzymes and DNA have similar shapes D. The structure of enzymes is determined by DNA

B. It takes a lot of energy for water to evaporate

What property of water makes it suitable as a coolant? A. It takes a lot of energy to increase the temperature of water B. It takes a lot of energy for water to evaporate C. Water molecules are cohesive and stick to the skin D. Water is a good solvent so it can transport heat from the body

B. Cis unsaturated fatty acid

What type of molecule is shown in this diagram? A. Trans saturated fatty acid B. Cis unsaturated fatty acid C. Cis saturated fatty acid D. Trans unsaturated fatty acid

D. Carbohydrate, protein, and fat

Which always contains carbon, hydrogen, and oxygen? A. Carbohydrate and protein B. Carbohydrate and fat C. Protein and fat D. Carbohydrate, protein, and fat

A. Sodium chloride is transported as Na+ and Cl- in blood

Which can be explained by the solvent properties of water? A. Sodium chloride is transported as Na+ and Cl- in blood B. Movement of water occurs under tension in the xylem C. Water is the coolant in sweat D. Ice floats on liquid water

C. Starch in plants; glycogen in animals

Which carbohydrates are used to provide energy storage in plants and animals? A. Starch in plants; glucose in animals B. Cellulose in plants; glycogen in animals C. Starch in plants; glycogen in animals D. Maltose in plants; glucose in animals

B

Which diagram represents the polarity of a water molecule?

C

Which graph shows the effect of increasing substrate concentration on enzyme activity?

C

Which is the activation energy of a reaction when it is catalyzed by an enzyme?

C

Which molecular structure correctly illustrates two amino acids linked by a peptide bond?

D. Glycogen

Which molecule is a polysaccharide? A. Glucagon B. Glucose C. Glycerol D. Glycogen

D. Both contain hydrogen atoms

Which of the following is TRUE about a polar amino acid and cellulose? A. Both are polysaccharides B. Both contain nitrogen C. Both are hydrophobic D. Both contain hydrogen atoms

B. III contains peptide bonds; II and IV are sugar molecules

Which of the molecules shown contain peptide bonds or are sugar molecules? A. I and III contain peptide bonds; II is sugar molecule B. III contains peptide bonds; II and IV are sugar molecules C. I, III, and IV contain peptide bonds; II is sugar molecule D. I contains peptide bonds; III and IV are sugar molecules

B. I and III only

Which statements correctly explain properties of water? I. Water is a useful medium for metabolic reactions as many substances dissolve in water II. Water is useful as a coolant as it takes a small amount of heat energy to change its temperature III. Water molecules are cohesive which helps water transport in the roots and stems of plants A. I and II only B. I and III only C. II and III only D. I, II, and III

A

Which structure represents a fatty acid?

A. Peptide

Which type of molecule is shown in the diagram? A. Peptide B. Carbohydrate C. Lipid D. Nucleic acid

B. The three dimensional structure of the enzyme becomes changed

Why does exposure to high temperatures cause an enzyme to lose its biological properties? A. The substrate blocks the active site at high temperatures B. The three dimensional structure of the enzyme becomes changed C. Chemical reactions cannot take place at high temperatures D. High temperatures increase the activation energy of reactions