Biochemistry; Biology Paper 1 Past Paper Questions; A-Level Edexcel, Exams of Advanced Education

Download Biochemistry; Biology Paper 1 Past Paper Questions; A-Level Edexcel and more Exams Advanced Education in PDF only on Docsity! Biochemistry; Biology Paper 1 Past Paper Questions; A-Level Edexcel Which is the correct statement about enzymes? A. enzymes decrease the activation energy of metabolic reactions and decrease reaction time. B. enzymes decrease the activation energy of metabolic reactions and increase reaction time. C. enzymes increase the activation energy of metabolic reactions and decrease reaction time. D. enzymes increase the activation energy of metabolic reactions and increase reaction time. In biological systems, enzymes catalyse chemical reactions by reducing the activation energy needed for those reactions to happen. Enzymes therefore accelerate metabolic reactions, thereby cutting down on the amount of time required for them to occur. The venom from some species of snake contains enzymes that affect the blood clotting process. What components of the blood clotting process are active enzymes? Important enzymes in the blood clotting cascade are thrombin and thromboplastin. We have an expert-written solution to this problem! Factor Xa is a clotting factor present in human blood. The table shows the effect of different masses of Factor Xa and snake venom on the time taken for blood to clot. Describe the effect of snake venom on the time taken for the blood to clot. The data shows that the time it takes for blood to clot reduces with an increase in the mass of snake venom administered. For example, blood takes 150 seconds to coagulate when 0 μg of snake venom is administered; this time significantly reduces to 104 seconds when Factor Xa is added together with 104 μg of snake venom. Snake venom is known to speed up the blood clotting process since this trend is true when more venom is added, with clotting times constantly being shorter than when Factor Xa is the sole factor present. Describe the structure of a globular protein. Globular proteins are distinguished by their compact, spherical, three-dimensional structure. A globular protein's structure often comprises tertiary structures created by interactions such as disulfide bonds, ionic bonds, and hydrophobic interactions between amino acid residues, as well as secondary structures sustained by hydrogen bonds, such as alpha helices and beta sheets. When succinate is converted into fumarate, succinate is A. hydrolysed B. oxidised C. phosphorylated D. reduced Succinate is oxidised during the process by which succinate dehydrogenase transforms it into fumarate. Chloroplasts are thought to be derived from cyanobacteria. It is estimated that there are 1×10^10 carbon atoms in one cyanobacterial cell. Ten photons of light are needed to fix one carbon atom. Calculate the number of photons of light needed to fix enough carbon to form one cyanobacterial cell. Total number of photons = Total number of carbon atoms x Number of photons per carbon atom Total number of photons = (1×10^10)×(10) Total number of photons = 1×10^11 For one cyanobacterial cell to form, 1×10^11 photons of light are required to fix enough carbon. We have an expert-written solution to this problem! The number of photons of light needed to fix enough carbon to form one cyanobacterial cell is 10^11. Explain why the value calculated for the number of photons of light needed to fix enough carbon to form one cyanobacterial cell is likely to be underestimated. The value tends to be underestimated since it assumes that all photons of light are efficiently caught and used during carbon fixation. In reality, though, not every photon is taken in by the chloroplasts, and not every photon that is taken in is used for photosynthesis.