1 The following statement is a method for managing one of the biological wastes according to Standard Operating Procedures. > Packed first in autoclave-resistant biohazard plastic bags, sterilised in an autoclave for decontamination and then placed into a biohazard bin. Biohazard plastic bags cannot be thrown into regular waste baskets. What is the biological waste that uses the above method? flag bookmark A Category A (sharp wastes) B Category B (non-sharp wastes) C Category C (animal carcasses) D Category D (liquids) T4 Chapter 1.2 Safety and Rules in Biology Laboratory Non-sharp biological waste such as used gloves, Petri dishes and cotton wool is packed in autoclave-resistant biohazard bags, autoclaved and then put into a biohazard bin. Sharp waste goes into a special sharps bin, animal carcasses are frozen before disposal, and liquids are autoclaved and poured away.
2 Which of the following is correct about the cellular structure and its function? | | Cellular component | Function | |---|---|---| | A | Ribosome | To synthesise lipids | | B | Lysosome | To produce energy | | C | Endoplasmic reticulum | To transport substances to the Golgi apparatus | | D | Cell wall | To allow the passage of materials in and out of the cell | flag bookmark A Ribosome – To synthesise lipids B Lysosome – To produce energy C Endoplasmic reticulum – To transport substances to the Golgi apparatus D Cell wall – To allow the passage of materials in and out of the cell T4 Chapter 2.1 Cell structure and function The endoplasmic reticulum is a network of membranes that carries substances, such as proteins made by ribosomes, to the Golgi apparatus. Ribosomes make proteins, not lipids; mitochondria, not lysosomes, produce energy; the cell wall gives shape and support, while the plasma membrane controls what enters and leaves the cell. (The answer scheme first gave D, then corrected it to C.)
3 Mrs. Z prepared mango pickle to be sold at the school canteen. She cut the mango into small slices and mixed them with a concentrated sugar solution. Which of the following shows the mango cell after being immersed in the sugar solution for five hours? flag bookmark A B C D T4 Chapter 3.4 Movement of Substances Across a Plasma Membrane and Its Application in Daily Life The concentrated sugar solution is hypertonic to the mango cells. Water leaves the cells by osmosis, the vacuole shrinks and the cytoplasm pulls away from the cell wall. The cell is plasmolysed, as shown in C. Pickling with sugar works this way: the plasmolysed cells keep the fruit from spoiling.
4 Diagram 1 shows a movement of substances across a plasma membrane. Which of the following is true about Diagram 1? flag bookmark A Accumulation or excretion of substances B The movement of substances follows the concentration gradient C The process continues until dynamic equilibrium is achieved D It requires specific channel proteins to bind with certain substances T4 Chapter 3.3 Movement of Substances Across a Plasma Membrane in Living Organisms The carrier protein uses energy from ATP (a phosphate group is attached to it) to change shape and move the substance, so this is active transport. Active transport moves substances against the concentration gradient, so it lets cells accumulate or get rid of substances. It does not stop at equilibrium, and it uses carrier proteins, not channel proteins.
5 The following statements are about substance L. - Does not form chemical bonds with additional hydrogen atoms. - Its fatty acids have only single bonds between carbon atoms. Which food contains substance L? flag bookmark A Olive oil B Salmon C Avocado D Butter T4 Chapter 4.4 Lipids Substance L is a saturated fat: its fatty acids have only single C–C bonds, so they cannot take up more hydrogen atoms. Saturated fats come mainly from animals and are solid at room temperature, such as butter. Olive oil, avocado and salmon are rich in unsaturated fats.
6 Diagram 2 shows the action of the enzyme sucrase. What are R, S and T? | | R | S | T | |---|---|---|---| | A | Sucrase | Lactose | Glucose | | B | Sucrase | Glucose | Glucose | | C | Sucrase | Galactose | Glucose | | D | Sucrase | Glucose | Fructose | flag bookmark A Sucrase – Lactose – Glucose B Sucrase – Glucose – Glucose C Sucrase – Galactose – Glucose D Sucrase – Glucose – Fructose T4 Chapter 5.2 Enzyme R is the enzyme sucrase, which is unchanged at the end. Sucrase hydrolyses sucrose into one glucose and one fructose, so S and T are glucose and fructose. Lactose gives glucose and galactose, and maltose gives two glucose.
7 Diagram 3 shows a shirt washed by Puan S using tap water. The stain on the shirt could not be removed completely even though it had been washed using an enzyme-powered detergent. The amount of detergent used followed the suggestion on the detergent box. What change can Puan S make to remove the stain? flag bookmark A Increase the amount of detergent used to two times the suggested measure B Reduce the amount of detergent used by two times C Use warm water to wash the cloth D Use cold water to wash the cloth T4 Chapter 5.3 Application of Enzymes in Daily Life Enzymes in biological detergents work best at their optimum temperature, about 37–40 °C. Cold tap water slows the enzymes down, so the stain is not fully digested. Washing with warm water brings the enzymes close to their optimum temperature so they break down the stain faster. Adding more detergent does not fix the low temperature.
8 Diagram 4 shows a complete cell cycle. State the chromosomal behaviour at T. flag bookmark A DNA is synthesised and replicated to form sister chromatids B The homologous chromosomes line up at the middle of the cell C Sister chromatids are separated by the shortening of the spindle fibres D Cytokinesis occurs T4 Chapter 6.2 Cell Cycle and Mitosis T lies in the long interphase part of the cycle (the inner arrow), in the S phase. During the S phase, DNA is synthesised and replicated, so each chromosome becomes two sister chromatids. The other options happen during mitosis and cytokinesis (M phase).
9 Diagram 5 shows the karyotype of an individual with Down syndrome. Which of the following statements describes the event that formed the karyotype in Diagram 5? flag bookmark A Uncontrolled mitosis B Non-disjunction of chromosomes during anaphase II C Chromosomes are not arranged at random on the equatorial plane during metaphase II D Incomplete cytokinesis after nuclear division T4 Chapter 6.4 Issues of Cell Division on Human Health The karyotype has three copies of chromosome 21 (47 chromosomes). This comes from non-disjunction during meiosis: a pair of chromosomes or sister chromatids fails to separate, for example in anaphase II, so one gamete gets an extra chromosome 21. Uncontrolled mitosis causes cancer.
10 Fermentation occurs in limited oxygen conditions or without oxygen, while aerobic respiration occurs in the presence of oxygen. Which of the following is correct regarding the differences between aerobic respiration and fermentation? | | Aerobic respiration | Fermentation | |---|---|---| | A | Occurs in the cytoplasm | Occurs in the cytoplasm and mitochondria | | B | Does not produce water | Produces water | | C | Glucose is not oxidised completely into ethanol and carbon dioxide or lactic acid | Glucose is oxidised completely into carbon dioxide and water | | D | One molecule of glucose generates 2898 kJ of energy | One molecule of glucose generates 210 kJ or 150 kJ of energy | flag bookmark A Cytoplasm – Cytoplasm and mitochondria B No water – Produces water C Incomplete oxidation – Complete oxidation D 2898 kJ – 210 kJ or 150 kJ T4 Chapter 7.3 Fermentation Aerobic respiration oxidises glucose completely into carbon dioxide and water and releases 2898 kJ per mole of glucose. Fermentation breaks glucose down only partly, into lactic acid (150 kJ) or ethanol and carbon dioxide (210 kJ). Options A, B and C describe the two processes the wrong way round.