Biology Revision

Biology Revision – Chemical And Cellular Basis of Life (2)

Multiple Choice Questions

Water And Life

1. Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?
the absorption of heat by the breaking of hydrogen bonds
water’s change in density when it condenses
water’s ability to dissolve molecules in the air
the release of heat by the formation of hydrogen bonds
water’s high surface tension

2. The bonds that are broken when water vaporizes are
hydrogen bonds between water molecules.
ionic bonds.
covalent bonds between atoms within water molecules.
polar covalent bonds.
nonpolar covalent bonds.

Main Organic Compounds of Life

3. Which of the following categories includes all others in the list?

4. The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the α form. Which of the following could amylase break down?
glycogen, starch, and amylopectin
glycogen and cellulose
cellulose and chitin
starch and chitin
starch, amylopectin, and cellulose

5. Which of the following statements concerning unsaturated fats is true?
They have double bonds in the carbon chains of their fatty acids.
They are more common in animals than in plants.
They generally solidify at room temperature.
They contain more hydrogen than do saturated fats having the same number of carbon atoms.
They have fewer fatty acid molecules per fat molecule.

6. The structural level of a protein least affected by a disruption in hydrogen bonding is the
primary level.
]quaternary level.
secondary level.
All structural levels are equally affected.
tertiary level.

7. Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?
The phosphodiester linkages of the polynucleotide backbone would be broken
The two strands of the double helix would separate.
The purines would be separated from the deoxyribose sugars.
The pyrimidines would be separated from the deoxyribose sugars.
All bases would be separated from the deoxyribose sugars.

8. The molecular formula for glucose is . What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions?

9. Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?
5′-ATGC-3′ with 5′-GCAT-3′
5′-purine-pyrimidine-purine-pyrimidine-3′ with 3′-purine-pyrimidine-purine pyrimidine-5′
5′-AGCT-3′ with 5′-TCGA-3′
5′-GCGC-3′ with 5′-TATA-3′
All of these pairs are correct.

10. Which elements are found in amino acids before they are assembled into protein chains?
Carbon, hydrogen, nitrogen, sulfur and oxygen.
Hydrogen, carbon, sulfur and nitrogen.
Nitrogen, oxygen, sulfur, phosphorous and carbon.
Oxygen, phosphorous, nitrogen and hydrogen.
Hydrogen, phosphorous, carbon and nitrogen.

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