Self Test Questions 01

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					Self-Test Questions (STQ) - Check your Progress
Unit 01 - The Biochemical Basis of Life

STQ 01.01 -   a) What is the atomic number of carbon?
              ANS. 6
              b) What is the mass number for chlorine?
              ANS. 35 (17 + 18)
              c) Is water an element or a compound?
              ANS. - a compound of hydrogen and oxygen
              d) Is oxygen an element or a compound?
              ANS. an element

STQ 01.02 -   a) What is an ion?
              ANS. a charged atom or molecule
              b) What is the difference between an anion and a cation?
              ANS. an anion is negatively charged and a cation is positively charged
              c) Give two key properties of ions
              ANS. ions are charged and ions are stable
              d) Has the magnesium ion (Mg2+) gained or lost two electrons?
              ANS. it has lost two (negative) electrons

STQ 01.03 -   a) What is the difference between ionic and covalent bonds?
              ANS. an ionic bond is formed when oppositely charged ions are attracted. A covalent
              bond is formed by atoms sharing electrons
              b) Explain why water molecules have polarity
              ANS. there is an imbalance of charge between the oxygen atom and the smaller hydrogen
              atoms due to the distribution of electrons. The oxygen region is more negatively charged
              than the hydrogen region.
              c) How many oxygen atoms are there in 2HCO3-?
              ANS. 6
              d) Balance this equation - H2 + O2 - H2O
              ANS. 2H2 + O2 - 2H2O

STQ 01.04 -   a) Is a solution of pH 5.0 more or less acidic than a solution of pH 6.0?
              ANS. pH 5.0 is ten time more acidic than pH 6.0
              b) Are there more or less hydrogen ions (H+) in a solution of pH 5.0
                 compared to a solution of pH 6.0?
              ANS. more H+ in pH 5.0
              c) Why might small changes in pH represent large changes in acidity?
              ANS. the pH scale is a log scale so a small change in pH represents a large change in the
              number of hydrogen ions

STQ 01.05 -   a) What is the chemical difference between a monosaccharide, a
              disaccharide and a polysaccharide?
              ANS. a monosaccharide is a single sugar. A disaccharide is two monosaccharides and a
              polysaccharide is a polymer (chain) of monosaccharides
              b) Give an example of a monosaccharide, a disaccharide and a polysaccharide
              ANS. monosaccharide - glucose, fructose and galactose
                    disaccharide - maltose, sucrose and lactose
                    polysaccharide - glycogen, starch and cellulose
              c) Why does glycogen not increase the osmolarity of cells?
              ANS. because it is insoluble
STQ 01.06 -   a) Explain the chemical difference between a saturated and unsaturated fat.
              ANS. a saturated fat has all its fatty acid carbon atoms bonded to the maximum number
              of hydrogen atoms. An unsaturated fat has some double bonds between its fatty acid
              carbons - and so less hydrogens
              b) Give one source of saturated and unsaturated fat in the Western diet.
              ANS. most animal fats are saturated and most plant oils are unsaturated
              c) Why will lipids not dissolve in water?
              ANS. because lipids are non-polar molecules and there is no ionic attraction between the
              non-polar lipid and the polar water molecules. Lipids molecules have no tendency to
              disperse in water

STQ 01.07 -   a) Name a type of protein that protects us against pathogens.
              ANS. antibodies (immunoglobulins)
              b) Name a type of protein that allows distant parts of the body to communicate.
              ANS. hormones (note that not all hormones are proteins)
              c) Name two proteins that produce movement in muscles.
              ANS. actin and myosin
              d) What are the main components of proteins?
              ANS. amino acids

STQ 01.08 -   a) List the four stages in the structure of a protein
              ANS. primary, secondary, tertiary and quaternary
              b) What is a biochemical pathway?
              ANS. the conversion of one substance into another in a series of steps, each catalysed by
              an enzyme
              c) What are the main fuels for energy production in cells?
              ANS. lipids and glucose
              d) What is the process called where these fuels are broken down to produce
              ANS. cellular respiration

STQ 01.09 -   a) Is ADP phosphorylated or dephosphorylated to form ATP?
              ANS. phosphorylated
              b) What process in plants uses sunlight, CO2 and H2O to make glucose?
              ANS. photosynthesis
              c) Energy cannot be destroyed so what happens to the waste energy released
                  when ATP takes part in a biochemical reaction?
              ANS. waste energy is converted into heat which maintains our steady internal
              d) What is the fate of atmospheric oxygen (O2) in the process of oxidative
              ANS. atmospheric oxygen combines with hydrogen ions to form water

STQ 01.10     a) Which contains more stored energy - a gram of fat or a gram of
              ANS. a gram of fat which contains 39 kj/g energy compared to 17kj/g
              b) When amino acids are broken down for energy, what happens to the
                 nitrogen from the amine group?
              ANS. transformed into urea
              c) What substance produced in anaerobic respiration may cause angina pain?
              ANS. lactic acid

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