Bio Past paper

• Lactate (Lactic acid) is produced when the horse runs, causing it to respire anaerobically.
• Lactate needs to be broken down after the horse stops running, causing it to breathe faster and deeper for a period of time.
• Blood contains molecules like oxygen and glucose which are transported to the foetus.
• These molecules are required to carry out respiration for the production of ATP.
• ATP produced during the process allows active transport to occur in cells of the foetus.
• The rate of digestion of starch will increase with the increase in temperature because there is more collision between the enzyme and the substrate.
• Above the optimum temperature, the rate of reaction would slow down as the enzyme will get denatured because the enzymes are made up of proteins and proteins are broken down by heat.
• The active site is destroyed and the substrate can no longer bind to the active site.
• E-cigarettes contain nicotine which narrows blood vessels and increases blood pressure, which can lead to coronary heart disease.
• Non-smokers may start using e-cigarettes.
• E-cigarettes may cause damage to the lungs.
• Viruses are spread in air.
• Malaria is spread by mosquitoes.
• Typhoid is spread by drinking contaminated water, eating contaminated food, housefly.
• The alveolus contains greater amount of carbon-dioxide.
• The alveolus contains less amount of oxygen.
• Air in the alveolus is warmer than in the atmosphere.
• The walls of the alveoli are one cell thick.
• The alveoli have a large surface area.
• The walls of the alveoli have a moist lining which allows gases to exchange efficiently.
• The alveoli are richly supplied with blood vessels.
• Capillaries have a narrow lumen.
• The wall of the capillaries is one cell thick.
• The function of the ear ossicles is to transmit vibration from the ear drum across the middle ear to the oval window or cochlea.
• The vibrations caused by the ear ossicles cause the hair cell in the basilar membrane to move, stimulating the receptor cells and generating nerve impulses.
• Half of the extra water that a person drinks still leaves the body in urine because when there is high volume of water in the blood, the pituitary gland releases a low level of ADH which makes the collecting duct less permeable and the water leaves the body as urine.
• Waste products are continuously produced by the body which need to be removed from the body in urine.
• Waste products if not removed can be toxic to the body.
• Blood contains cells (red blood cells) as well as a fluid component, whereas plasma does not.
• Plasma is colorless whereas whole blood is red.
• The random change in the base sequence of the DNA is called mutation.
• Mutation causes changes in genotype that can produce different phenotype.
• The water in the pond is changed every day to ensure that the waste products of the fish and to ensure that there is a continuous and sufficient supply of O2 in the H2O.
• Palisade mesophyll layer is made up of palisade cells which contain densely packed chloroplast to absorb all the available light for photosynthesis.
• Palisade cells are elongated and closely packed which maximizes the absorption of sunlight for photosynthesis.
• Spongy mesophyll layer contains air spaces to allow carbon-dioxide to diffuse out of the leaf and oxygen to diffuse into the leaf.
• Guard cells open or close stomata, allowing carbon-dioxide into the leaf and oxygen out the leaf.
• Reflex arc is a pathway that controls reflex action which is rapid and automatic, since there is no involvement of brain so the response is rapid which prevents the body from danger, for example, touching a hot object.
• Percentile chart helps to detect if the baby is growing or losing too much mass.
• The molar is more likely to decay than other types of teeth because it contains a large surface area with ridges/crevices where food particles can get trapped.