BLG1501 EXAM PACK 2026

UNISA BLG1501 Memorandum May/June 2022 EXAMINATION 100 Marks SEMESTER 1 Question 1 1.1 An atom is defined as the smallest particle of _____ A. a compound that can take part in chemical reaction. B. an element that can take part in chemical reaction. C. a molecule that reacts with other molecules. D. an isotope that take part in chemical reaction. E. a compound that react with other compounds. 1.2 The three domains of life are _____ A. eukarya, fungi and bacteria. B. eukarya, archaea and bacteria. C. eukarya, fungi and animalia. D. eukarya, archaea and fungi. E. eukarya, bacteria and animalia 1.3 The correct definition of isotopes is _____ A. atoms of the different elements that have the same number of neutrons, but differ in the number of protons. B. atoms of the same element containing the same number of protons, but differ in the number of electrons. C. atoms of the same element containing the same number of protons, but differ in the number of neutrons. D. atoms of the same element containing the same number of electrons, but differ in the number of neutrons. E. atoms of different elements that have the same number of neutrons, but differ in the number of electrons. 1.4 Van der Waals interaction is a bond formed by _____ A. polar positively charged and polar negatively charged atoms. B. polar positively charged and non-polar negatively charged atoms. C. non-polar positively charged and non-polar negatively charged atoms. D. positively charged and negatively charged atoms. E. non-polar positively charged and negatively charged atoms. 1.5 Chitin is an example of a _____ A. polypeptide. B. polysaccharide. C. fat. D. nucleic acid. E. glycerol. 1.6 The electron configuration 1s22s22p4 , belongs to _____ A. carbon. B. oxygen. C. nitrogen. D. neon. E. magnesium. 1.7 Ribosomes are responsible for _____ A. protein synthesis. B. digestive compartments. C. photosynthesis. D. controlling the centre of the cell. E. the removal of waste from the cell. 1.8 The mass number refers to _____ A. the number of protons in an atom. B. the combined number of protons and neutrons in an atom. C. the number of electrons in an atom. D. the combined number of protons and electrons in an atom. E. the number of neutrons and electrons in an atom. 1.9 Chloroplasts are responsible for _____ A. the shipping and receiving centre. B. digestive compartments. C. photosynthesis. D. controlling the centre of the cell. E. protein synthesis. 1.10 In DNA, double helix, adenine pairs with _____, and guanine pairs with _____ A. cytosine, thymine. B. guanine, adenine. C. uracil, cytosine. D. thymine, cytosine. E. cytosine, uracil. Total: 20 Question 2 2.1 Describe the structure and functions of four polysaccharides. (8) Answer: Starch = Glucose polymer that is a storage polysaccharide in plants. Helical glucose polymer with alpha 1-4 linkages Glycogen = Glucose polymer that is a storage polysaccharide in animals. Large glucose polymer that is more highly branched (alpha 1-4 and 4-6 linkages) S - The Marketplace to Buy and Sell your Study Material than amylopectin Cellulose = Cellulose reinforces plant cell walls. Hydrogen bonds hold together parallel cellulose molecules in bundles of microfibrils. Linear unbranched polymer of D-glucose in (alpha 1-4, beta 4-6) linkages. Chitin = A structural polysaccharide that is a polymer of an amino sugar Forms exoskeletons of arthropods and found as building material in the cell walls of some fungi. 2.2 Define the term "buffer". In the definition, refer to suitable examples of a buffer and indicate its application in living systems. (5) Answer: Buffer = Substance that minimizes large sudden changes in pH. Work by accepting H+ ions from solution when they are in excess and by donating H+ ions to the solution when they have been depleted Example: Bicarbonate buffer 2.3 Compare and contrast the processes of fermentation and cellular respiration. (12) Answer: Fermentation Cellular respiration The final electron acceptor is an organic molecule pyruvate (lactic acid fermentation) or acetaldehyde (alcohol fermentation) The final electron acceptor is oxygen Harvests less energy Harvests more energy Yields 2 ATPs Yields 38 ATPs Anaerobic conditions Aerobic conditions Question 3 3.1 Explain how edges and corridors can strongly influence landscape biodiversity. (6) Answer: Boundaries (edges) between ecosystems and along prominent features within ecosystems have unique sets of physical conditions and communities of species. S - The Marketplace to Buy and Sell your Study Material Downloaded by: LIBRARY | Distribution of this document is illegal Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material Edges become more extensive as habitat fragmentation increases, and edgeadapted species may become more dominant. Movement corridors may promote dispersal and help sustain populations or they may promote harmful conditions such as disease. 3.2 Describe the structure and function of ribosomes. (10) Answer: Ribosomes are made of two types of subunits – large and small subunits. The ribosomal subunits are made up of proteins and RNA molecules are called ribosomal RNA, or rRNA. The ribosomal subunits are made in the nucleolus. The subunits are then transported via the nuclear pores to the cytoplasm. Approximately two-thirds of the mass of a ribosome is rRNA. The ribosomes of eukaryotes are slightly larger than those of prokaryotes. Ribosomes function either free in the cytosol or bound to endoplasmic reticulum. Bound and free ribosomes are structurally identical and interchangeable. The ribosomes play a very important role in protein synthesis, which is the process by which proteins are made from individual amino acids. Without the ribosomes the message would not be read, thus proteins could not be produced. Ribosomes play a role in the formation of polypeptides. 3.3 List the four major threats to biodiversity and give an example of each. (12) Answer: 1. Climate change: e.g. change in climate courses alteration in life on earth over time, like ecosystems destroyed and species become extinct 2. Deforestation: e.g. deforestation causes habitat loss and predation to animals exposed form shelter 3. Pollution: e.g. all types of pollution (air, water or land) causes health issues threatening different life forms on earth 4. Over-exploration: Over-exploration causes a shift or loss in biodiversity e.g. over hunting, over fishing or over harvesting causes loss of species and sometimes extinction Question 4 4.1 A purple flower with an unknown genotype is crossed with a white flower. Determine the genotype of the purple flower if purple (P) is dominant and white (p) is recessive. (20) Answer: Purple flower (P) dominant X white flower (p) recessive S - The Marketplace to Buy and Sell your Study Material Downloaded by: LIBRARY | Distribution of this document is illegal Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material Test cross: So if PP x pp And if Pp x pp So in the 1st punnett square all off springs are Pp meaning they all have purple flowers. This indicates that all purple-flowered off spring show that the unknown parental genotype is homozygous dominant. And in the 2nd punnett square 50% of the off springs is Pp (purple) and 50% pp (white) thus showing a 1:1 ratio of purple and white off springs indicating that the unknown parental genotype is heterozygous dominant. 4.2 How is the accumulation of chlorofluorocarbons responsible for depleting the atmospheric zone? (7) When breakdown products of the chlorofluorocarbons rise to the stratosphere, the chlorine they contained reacts with the ozone reducing it to O2. Subsequent chemical reactions liberate the chlorine allowing it to react with other ozone molecules in a catalytic chain reaction. Total marks 100 Pp Pp pp pp Pp Pp pp pp Dominant phenotype Unknown genotype PP or Pp Recessive phenotype Known genotype pp X P P p p P p p p S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material BLG1501 MAY/JUNE EXAMINATION 2011 Marks: 100 MEMORANDUM Duration: 2 hours QUESTION 1 1. B 2. B 3. A 4. B 5. C 6. D 7. C 8. D 9. A 10. D (10 x 2 =20) QUESTION 2 2.1 Plant cell Animal cell Consists of cell wall No cell wall Regular fixed shape Irregular Large central vacuole and tonoplast If present small vacuole Chloroplast present Absent No lysosomes Present No centrosomes Present (12) 2.2.1 Diploid – two sets of chromosomes per nucleus. 2.2.2 Primosome – a complex of proteins responsible for synthesizing the RNA primers required in DNA synthesis. 2.2.3 Ecotone – transition zone where two communities or biomes meet and integrate. S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material 2 BLG1501 MAY/JUNE 2011 2.2.4 Enthalpy – the total potential energy of a system. 2.2.5 Climax community – succession progress to a stable persistent community. (2 X 5 = 10) 2.3 In asexual reproduction, one parent produces genetically identical offspring by mitosis. Sexual reproduction is a type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents. Gametes are produced through meiosis. (3) [25] QUESTION 3 3.1 Boundaries (edges) between ecosystems and along prominent features within ecosystems have unique sets of physical conditions and communities of species. Edges become more extensive as habitat fragmentation increases, and edge-adapted species may become more dominant. Movement corridors may promote dispersal and help sustain populations or they may promote harmful conditions such as disease. (6) 3.2 Alcohol fermentation Lactic acid fermentation Pyruvate is converted to ethanol in two steps Pyruvate is directly reduced by NADH to form lactate as an end product Carbon dioxide is released from the pyruvate and forms acetaldehyde No release of carbon dioxide Acetaldehyde is reduced by NADH to ethanol (6) 3.3 S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material 3 BLG1501 MAY/JUNE 2011 Fermentation Cellular respiration Final electron acceptor is an organic molecule pyruvate ( lactic acid fermentation or acetaldehyde (alcohol fermentation) The final electron acceptor is oxygen Harvest less energy Harvest more energy Yields 2 ATPs Yields 38 ATPs Anaerobic conditions Aerobic condition (10) 3.4 The three domains of life are Bacteria Archaea Eukarya (3) QUESTION 4 4.1.1 P-generation: female x male BBTT bbtt ↓ ↓ Gametes : BT bt (4) 3.1.2 F1- generation : BbTt (1) 3.1.3 F2-generation : BbTt x BbTt Gametes BT Bt bT Bt BT BBTT BBTt BbTT BbTt Bt BBTt BBtt BbTt Bbtt bT BbTT BbTt BbTT bbTt bt BbTt Bbtt bbTt bbtt (10) 3.1.4 9:3:3:1 (1) S - The Marketplace to Buy and Sell your Study Material Downloaded by: ayandambanjwa | Distribution of this document is illegal Downloaded by: LIBRARY | Want to earn $103 per month? S - The Marketplace to Buy and Sell your Study Material 4 BLG1501 MAY/JUNE 2011 3.1.5 9 - black, long tail 3 - white , long tail 3 - black, short tail 1- white, short tail (3) {19} 3.2 Starch Structure: Is formed by glucose monomers joined by 1-4 linkages. Function : When starch is broken down the available glucose serve as nutrient for animal cells(including humans) Glycogen Structure : It is formed by polymers of glucose which form large number of branches. Function: When hydrolysed the glycogen releases glucose when the sugar demand increases. Cellulose Structure : Is a polymer formed by the glucose in the β configuration making every glucose upside down with respect to next joined ones. Function : Major component of the plant cell wall. Building material for plants. Chitin Structure: The structure is similar to cellulose except that chitin has a nitrogen – containing appendages in its glucose monomer. Functions: The exoskeleton of arthropods,(insects, spiders , crustaceans and related animals is composed of chitin. In fungi it is used as the building material for their cell walls. (8) 3.3 A buffer is a substance that minimizes the changes in the concentrations of H+ and OHin a solution. In living systems, for example human blood, buffering capacity of the blood prevents the swing s in pH. The normal pH of human blood is 7.4, which slightly basic. If the pH increases to more than the normal one, the buffer works by accepting H + from the solution when they are in excess and donating H+ to the solution when they have been lacking. (3) [30 TOTAL MARKS: 100