Question 1: Define DNA and describe its primary function in living organisms.

Answer: DNA (Deoxyribonucleic Acid) is the molecule that carries genetic information in living organisms, determining inherited traits by encoding instructions for protein synthesis.

Question 2: Identify the four types of nitrogenous bases found in DNA and specify which pair together.

Answer: The four nitrogenous bases are Adenine, Thymine, Cytosine, and Guanine. Adenine pairs with Thymine, and Cytosine pairs with Guanine.

Question 3: Explain the significance of the sugar-phosphate backbone in DNA structure.

Answer: The sugar-phosphate backbone provides structural support to the DNA molecule, forming the sides of the double helix and ensuring the stability of the genetic code.

Question 1: Given that the average molecular weights of the bases are Adenine (135 g/mol), Thymine (126 g/mol), Cytosine (111 g/mol), and Guanine (151 g/mol), and that the deoxyribose sugar weighs 134 g/mol, calculate the molecular weight of a nucleotide with Adenine and deoxyribose.

Answer: Adenine (135 g/mol) + deoxyribose (134 g/mol) = 269 g/mol

Question 1: Describe a theoretical experiment to extract DNA from a fruit sample. Include the main steps and safety precautions.

Answer: The experiment involves mashing the fruit, adding a detergent solution to break cell membranes, incubating the mixture, filtering to remove debris, adding alcohol to precipitate the DNA, and then spooling the DNA onto a glass rod. Safety precautions include wearing gloves and eye protection, handling chemicals carefully, and working in a well-ventilated area.

Question 1: A researcher measures the molecular weight of a DNA segment and finds it to be approximately 3.4 x 10^6 g/mol. If each nucleotide weighs roughly 330 g/mol, estimate the number of nucleotides in this DNA segment.

Answer: Number of nucleotides = Total molecular weight / weight per nucleotide = 3.4 x 10^6 g/mol / 330 g/mol ≈ 10291 nucleotides.

Question 1: Explain how the structure of DNA allows it to store and transfer genetic information. Include details about the double helix, base pairing, and the significance of complementary strands. (6 marks)

Answer: DNA's double helix structure provides stability and compactness, with sugar-phosphate backbones on the outside and nitrogenous bases on the inside. Base pairing (A with T, C with G) ensures accurate copying during cell division. Complementary strands enable precise replication and transcription, which are essential for storing and transferring genetic information.

Question 1: Discuss one way that knowledge of DNA structure is used in the development of genetic engineering or biotechnology products. Include potential benefits and ethical considerations.

Answer: Knowledge of DNA structure allows scientists to insert, delete, or modify genes in organisms (e.g., genetically modified crops). Benefits include increased yield and disease resistance, but ethical concerns involve biosafety, genetic diversity, and potential unintended effects.