BIOLOGY PAST QUESTIONS (SSCE)
physics past questions DETERMINATION OF THE GENOTYPE OF A DOMINANT PHENOTYPE VARIATION IN POPULATION english language past questions Commerce Past Questions
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Biology
GROWTH
GROWTH What is growth? Growth is the irreversible increase in dry mass, size and complexity of an organism brought about by the synthesis of new protoplasm. For growth to be effective, building up of materials (anabolism) must exceed the rate of breaking down (catabolism). In plants, growth is indefinite and apical while it is definite
CELL PROPERTIES AND FUNCTIONS
CELL PROPERTIES AND FUNCTIONS CELLULAR (INTERNAL/TISSUE) RESPIRATION The oxidation of glucose in the cell to release energy is known as cellular respiration and it occurs in the mitochondria of all living cells. There are two types of cellular respiration i.e. aerobic and anaerobic respiration AEROBIC RESPIRATION When cellular respiration takes place in the presence
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CELL AND ITS ENVIRONMENT
Environment/Nature and State of Matter Living cells are known to be surrounded by a watery environment. This may include: Fresh/salt water in which the unicellular organisms live, Intercellular fluid that bath the bodies of cells of higher animals. The nature of states of matter makes diffusion and osmosis possible. Matter can be defined as
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DIFFERENCES BETWEEN PLANTS AND ANIMALS
DIFFERENCES BETWEEN PLANTS AND ANIMALS All living organisms can be generally classified as plants or animals. However, plants can be distinguished from animals in the following ways: PLANTS ANIMALS 1. Undergo passive movement. Undergo free or active movement with well developed organs of locomotion. 2. Gaseous exchange takes place through the entire body. Gaseous
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MICROSCOPE PARTS AND FUNCTIONS
MICROSCOPE PARTS AND FUNCTIONS A microscope is an instrument used in magnifying and viewing organisms smaller than 0.1mm that is too tiny to be seen by the human eyes. A compound light microscope consists of the following parts: Revolving nose piece: it is used for selecting lens to be used and to be in line
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BIOLOGY AND LIVING THINGS
BIOLOGY AND LIVING THINGS BIOLOGY AS AN INQUIRY IN SCIENCE Science is the study of nature (living and non-living things). Biology is a science that studies living things in nature. Biology was formed from the Greek words “Bio” (meaning life) and “logos” (meaning, study of). The organisms studied in biology are generally classified into plants
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JAUNDICE (SKIN AND EYES)
JAUNDICE (SKIN AND EYES) This is a yellow colouration of the skin and eyes. Cause: Presence of excess bile pigments. This happens due to blockage of bile duct or destruction of liver. Symptoms: Yellow pigmentation of skin and eyes, nausea, vomiting and lack of appetite. Itching of skin. Treatment Removal of stones from the gall bladder
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LIVER EXCRETION
LIVER EXCRETION Role of Liver in Excretion The liver lies below the diaphragm and it receives blood from hepatic artery and hepatic portal vein. Blood flows out of the liver through hepatic vein. Excretion of Nitrogenous Wastes Excess amino acids cannot be stored in the body; they are deaminated in the liver. Hydrogen is added
EXCRETION AND HOMEOSTASIS (PLANT AND ANIMAL)
EXCRETION AND HOMEOSTASIS (PLANT AND ANIMAL) Introduction What is Excretion? Excretion is the process by which living organisms separate and eliminate waste products of metabolism from body cells. If these substances were left to accumulate, they would be toxic to the cells. Egestion is the removal of undigested materials from the alimentary canals of animals.
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DISEASES OF THE RESPIRATORY SYSTEM
DISEASES OF THE RESPIRATORY SYSTEM Asthma Asthma is a chronic disease characterized by narrowing of air passages. Causes: Allergy Due to pollen, dust, fur, animal hair, spores among others. If these substances are inhaled, they trigger release of chemical substances and they may cause swelling of the bronchioles and bring about an asthma attack. Heredity
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GASEOUS EXCHANGE IN A MAMMAL – HUMAN
GASEOUS EXCHANGE IN A MAMMAL – HUMAN The breathing system of a mammal consists of a pair of lungs which are thin-walled elastic sacs lying in the thoracic cavity. The thoracic cavity consists of vertebrae, sternum, ribs and intercostal muscles. The thoracic cavity is separated from the abdominal cavity by the diaphragm. The lungs
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GASEOUS EXCHANGE IN AN AMPHIBIAN – FROG
GASEOUS EXCHANGE IN AN AMPHIBIAN – FROG An adult frog lives on land but goes back into the water during the breeding season. A frog uses three different respiratory surfaces. These are the skin, buccal cavity and lungs. Skin The skin is used both in water and on land. It is quite efficient and
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GASEOUS EXCHANGE IN INSECTS
Gaseous exchange in insects e.g., grasshopper takes place across a system of tubes penetrating into the body known as the tracheal system. The main trachea communicate with atmosphere through tiny pores called spiracles. Spiracles are located at the sides of body segments; Two pairs on the thoracic segments and eight pairs on the sides of
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GASEOUS EXCHANGE IN ANIMALS
GASEOUS EXCHANGE IN ANIMALS All animals take in oxygen for oxidation of organic compounds to provide energy for cellular activities. The carbon (IV) oxide produced as a by-product is harmful to cells and has to be constantly removed from the body. Most animals have structures that are adapted for taking in oxygen and for removal
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AQUATIC PLANT STEMS
AQUATIC PLANT STEMS The water lily, Salvia and Wolfia whose stems remain in water are permeable to air and water. Oxygen dissolved in the water diffuses through the stem into the cells and carbon (IV) oxide diffuses out into the water. Gaseous Exchange in Roots Terrestrial Plants Gaseous exchange occurs in the root hair
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GASEOUS EXCHANGE IN PLANTS AND ANIMALS
GASEOUS EXCHANGE IN PLANTS AND ANIMALS Necessity for Gaseous Exchange in Living Organisms Living organisms require energy to perform cellular activities. The energy comes from breakdown of food in respiration. Carbon (IV) oxide is a by-product of respiration and its accumulation in cells is harmful which has to be removed. Most organisms use oxygen for
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GASEOUS EXCHANGE IN PLANTS
GASEOUS EXCHANGE IN PLANTS Oxygen is required by plants for the production of energy for cellular activities. Carbon (IV) oxide is required as a raw material for the synthesis of complex organic substances. Oxygen and carbon (IV) oxide are obtained from the atmosphere in the case of terrestrial plants and from the surrounding water in
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APPLICATION OF ANAEROBIC RESPIRATION IN INDUSTRY AND AT HOME INDUSTRY
Making of beer and wines. Ethanol in beer comes from fermentation of sugar (maltose) in germinating barley seeds. Sugar in fruits is broken down anaerobically to produce ethanol in wines. In the dairy industry, bacterial fermentation occurs in the production of several dairy products such as cheese, butter and yoghurt. In production of organic acids
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SUBSTRATES FOR RESPIRATION
SUBSTRATES FOR RESPIRATION Carbohydrate, mainly glucose is the main substrate inside cells. Lipids i.e. fatty acids and glycerol are also used. Fatty acids are used when the carbohydrates are exhausted. A molecule of lipid yields much more energy than a molecule of glucose. Proteins are not normally used for respiration. However during starvation they are
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