Paper Ib

REVISION 2 (56 Marks) IB Standard level Biology Dulwich College Shanghai Topic 3: Chemistry of Life 3. 1Chemical elements and water 3. 1. 1State that the most frequently occurring chemical elements in living things are carbon, hydrogen, oxygen and nitrogen. 3. 1. 2State that a variety of other elements are needed by living organisms, including sulphur, calcium, phosphorus, iron and sodium. 3. 1. 3State one role for each of the elements in 3. 1. 2. 3. 1. 4Draw and label a diagram showing the structure of water molecules to show their polarity and hydrogen bond formation. 3. 1. Outline the thermal, cohesive and solvent properties of water. 3. 1. 6Explain the relationship between the properties of water and its uses in living organisms as a coolant, medium for metabolic reactions and transport medium. 3. 2Carbohydrates, Lipids and Proteins 3. 2. 1Distinguish between organic and inorganic compounds. 3. 2. 2Identify amino acids, glucose, ribose and fatty acids from diagrams showing their structure. 3. 2. 3List three examples of each of monosaccharides, disaccharides and polysaccharides. 3. 2. 4State one function of glucose, lactose and glycogen in animals and of fructose, sucrose and cellulose in plants. . 2. 5Outline the role of condensation and hydrolysis in the relationships between monosaccharides, disaccharides and polysaccharides; between fatty acids, glycerol and triglycerides; and between amino acids and polypeptides. 3. 2. 6State three functions of lipids 3. 2. 7Compare the use of carbohydrates and lipids in energy storage. Paper 1 Multiple Choice (7 Marks) 1. Which is not a primary function of protein molecules? A. Hormones B. Energy storage C. Transport D. Structure 2. Which of the following could be a function of a membrane protein? A. Energy storage B. Enzymatic activity C. Oxygen uptake D. Thermal insulation 3.
What is the maximum number of fatty acids that can be condensed with glycerol? A. One B. Two C. Three D. Four 4. What is a role of carbohydrates in animal cells? A. As channels for passive transport B. As enzymes C. As energy storage D. As components of the animal cell wall 5. Which of the following terms correctly describe the molecule below? I. Monosaccharide II. Ribose III. Carbohydrate A. I only B. I and III only C. II and III only D. I, II and III 6. What causes water to have a relatively high boiling point? A. Hydrogen bonds between water molecules B. Hydrogen bonds between hydrogen and oxygen within water molecules C.
Cohesion between water molecules and the container in which the water is boiled D. Covalent bonds between hydrogen and oxygen within water molecules 7. Identify the atoms and ions from the table below. AtomsIons A. H+Na+OH–Cl– B. FeKCH3COO–H2O C. FeH2OCa2+N3 – D. NaCI–NO3 – Paper 2 Section A Data Analysis (7 marks) 1. Scientists have long been concerned about the effect of heavy metals in foods that we eat. Aquatic filter feeders including bivalves, such as mussels and oysters, are especially prone to accumulation of heavy metals. Calcium is taken into bivalves through protein channels, but other non-essential elements may also be taken in.

To investigate the relationship between the uptake of calcium and other elements, the bivalves Hyridella depressa and Velesunio ambiguous were placed in solutions containing ten times the normal level of calcium (Ca). The elements manganese (Mn), lead (Pb), cadmium (Cd) and cobalt (Co) were also present in the solutions at normal concentrations. The results are shown below. [Source: Reprinted from Markich Scott J. and Jeffree Ross A. , “Absorption of divalent trace metals as analogues of calcium by Australian freshwater bivalves: an explanation of how water hardness reduces metal toxicity”, Aquatic Toxicology (August 1994), vol. 9, issue 3–4, pp. 257–290, © 1994 with permission from Elsevier] ? (a)(i)Outline the effect of increasing calcium levels in the water on calcium levels in the tissue of the bivalves. (1) (ii)Outline the effect of increasing calcium levels in the water on metals other than calcium in the tissue of the bivalves. (1) (b)Suggest reasons for the effects of calcium on the levels of the other metals in the tissues. (2) (c)Evaluate the implications of these results for monitoring water quality in regions where bivalves are harvested. (3) Paper 2 Section A Short Structured (20 Marks) 1.
The complex structure of proteins can be explained in terms of four levels of structure, primary, secondary, tertiary and quaternary. (a)Primary structure involves the sequence of amino acids that are bonded together to form a polypeptide. State the name of the linkage that bonds the amino acids together. (1) (b)Beta pleated sheets are an example of secondary structure. State one other example. (1) (c)Tertiary structure in globular proteins involves the folding of polypeptides. State one type of bond that stabilizes the tertiary structure. (1) (d)Outline the quaternary structure of proteins. (2) 2.
State one named example of a fibrous protein and one named example of a globular protein. (2) 3. State two functions of proteins with a named example of each. (2) 4. Lipids are essential nutrients that must be included in the diet. (a)State one food rich in lipids suitable for a vegan diet. (1) (b)Outline two functions of lipids in the body. (2) (c)Discuss the possible health problems associated with diets rich in lipids. (4) 5. Living organisms produce a wide variety of organic compounds. (a)Define the term organic. (1) Organic compounds are made of chemical elements, which are therefore essential to living organisms. b)State the three most commonly occurring elements. (1) (c)Some organic compounds contain other elements. State one substance, or group of substances, that contains (i) nitrogen, (ii) phosphorus. (2) Section B Extended Response (22 Marks) 1. Outline the role of condensation and hydrolysis in the relationship between amino acids and dipeptides. (4) 2. Explain the secondary and tertiary levels of protein structure. (4) 3. Describe why carbohydrates and lipids are used as energy stores. (6) 4. Explain, with reference to its properties, the significance of water as a coolant, a means of transport and as a habitat. (8)

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