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ZIMSEC A Level · N2009

Biology Paper 2 November 2009

Questions
8
Total marks
17

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Questions
8
Pass mark
5
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Answer every question in the printed order, get marked at the end, then see the answers.

The questions

Question 101

[1 marks]biological molecules - proteins
Fig 1.1 is a diagram of protein tertiary structure. The bond labelled A forms by electrostatic attraction between two oppositely charged R-group (side chain) groups on the folded polypeptide chain. Bond A is best classified as a...
  1. AIonic bond
  2. BPeptide bond
  3. CDisulphide bond
  4. DHydrogen bond

Question 102

[1 marks]biological molecules - proteins
Fig 1.1 is a diagram of protein tertiary structure. The bond labelled B forms by weak electrostatic attraction between a hydrogen atom carrying a partial positive charge and an electronegative atom (such as oxygen or nitrogen) on a nearby R-group. Bond B is best classified as a...
  1. ADisulphide bond
  2. BHydrogen bond
  3. CIonic bond
  4. DPeptide bond

Question 103

[1 marks]biological molecules - proteins
In protein tertiary structure, the folded polypeptide chain is held in shape by several types of bond, including hydrogen bonds, ionic bonds, hydrophobic interactions and disulphide bonds. Which of these bond types is the strongest?
  1. AIonic bond
  2. BDisulphide bond
  3. CHydrogen bond
  4. DHydrophobic interaction

Question 104

[1 marks]biological molecules - proteins
Which of the following correctly distinguishes globular proteins from fibrous proteins?
  1. AGlobular proteins have a structural role such as forming collagen, whereas fibrous proteins have a metabolic role such as catalysing reactions.
  2. BGlobular proteins are built entirely from fibrous secondary structure, whereas fibrous proteins are built entirely from globular secondary structure.
  3. CGlobular proteins are soluble and roughly spherical in shape, whereas fibrous proteins are insoluble and elongated in shape.
  4. DGlobular proteins are insoluble and elongated in shape, whereas fibrous proteins are soluble and roughly spherical in shape.

Question 1001

[1 marks]nucleic acids - DNA replication
Deoxyribonucleic acid (DNA) is a polynucleotide in which each nucleotide is built from three chemical groupings: a five-carbon sugar, a phosphate group, and a nitrogenous base. Which of the following is NOT one of these three chemical groupings found in a DNA nucleotide?
  1. ADeoxyribose sugar
  2. BNitrogenous (organic) base
  3. CPhosphate group
  4. DRibose sugar

Question 1002

[1 marks]nucleic acids - DNA replication
The four nitrogenous bases found in DNA nucleotides fall into two chemical classes: purines (double-ringed) and pyrimidines (single-ringed). Which pair of bases is classified as purines?
  1. AAdenine and guanine
  2. BCytosine and thymine
  3. CGuanine and thymine
  4. DAdenine and cytosine

Question 1003

[1 marks]nucleic acids - DNA replication
During DNA replication, the double helix unwinds and each of the two original strands acts as a template for synthesising a new complementary strand. Once replication is complete, each of the two daughter DNA molecules produced consists of...
  1. Aone strand of DNA and one complementary strand made entirely of RNA
  2. Btwo original (parental) strands, with no newly synthesised material present
  3. Cone original parental strand and one newly synthesised (daughter) strand
  4. Dtwo newly synthesised strands, with no original parental material present

Question 1004

[1 marks]nucleic acids - DNA replication
During DNA replication, the original DNA molecule is copied to produce two new, genetically identical DNA molecules. What is the main biological importance of producing two exact copies of the DNA during replication?
  1. AIt significantly increases genetic variation among the daughter cells produced.
  2. BIt directly allows the daughter cells to specialise into different differentiated tissue types.
  3. CIt enables the daughter cells to repair pre-existing damage located in the parent DNA molecule.
  4. DIt ensures that the daughter cells produced by mitosis have DNA identical to the parent cell.

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