Here are the solutions to the Biology questions: 1. Use a digital device with internet connection to find out the levels of cell organisation. Write short notes on your findings. The levels of cell organization in living organisms are: Cells*: The basic structural and functional units of life. Tissues*: Groups of similar cells that work together to perform a specific function (e.g., muscle tissue, nervous tissue). Organs*: Structures made up of different types of tissues that work together to perform a specific function (e.g., heart, stomach). Organ Systems*: Groups of organs that cooperate to perform major functions in the body (e.g., digestive system, circulatory system). Organism*: A complete living being made up of multiple organ systems working together. 2. After a search activity, Jacob and his group members identified the heart and brain as examples of main organs of animals. Which other organs are they likely to list in their findings? Other main organs they are likely to list include: Lungs* Kidneys* Liver* Stomach* Intestines* Pancreas* Skin* 3. In the previous grades, you had learnt about organ systems in animals. Identify the organs making these organ systems in animals. a) Reproductive system: Ovaries, Testes, Uterus, Vagina, Penis, Vas deferens.* b) Circulatory system: Heart, Blood vessels (arteries, veins, capillaries), Blood.* c) Respiratory system: Lungs, Trachea, Bronchi, Diaphragm, Nasal cavity, Pharynx, Larynx.* d) Excretory system: Kidneys, Ureters, Urinary bladder, Urethra, Skin, Lungs, Liver.* 4. Briefly describe four chemicals of life. Carbohydrates*: Organic molecules composed of carbon, hydrogen, and oxygen, primarily serving as a source of energy and structural components (e.g., glucose, starch). Lipids*: Diverse group of organic molecules, including fats, oils, and steroids, characterized by their insolubility in water. They function in energy storage, insulation, and hormone production. Proteins*: Complex macromolecules made of amino acid chains. They perform a vast array of functions, including structural support, enzymatic catalysis, transport, and defense. Nucleic Acids*: DNA and RNA, which are polymers of nucleotides. They carry genetic information and are essential for protein synthesis. 5. Outline three differences between monosaccharides and polysaccharides. 1. Structure: Monosaccharides are simple sugars consisting of a single sugar unit (e.g., glucose, fructose), while polysaccharides are complex carbohydrates made of many monosaccharide units linked together (e.g., starch, cellulose). 2. Solubility: Monosaccharides are generally soluble in water and taste sweet, whereas most polysaccharides are insoluble or sparingly soluble in water and are not sweet. 3. Size: Monosaccharides are small molecules, while polysaccharides are large macromolecules. 6. Differentiate between sunflower oil and corn oil as examples of lipids if glycerol is the same in all lipids. While both sunflower oil and corn oil are triglycerides (lipids formed from glycerol and fatty acids), they differ in their fatty acid composition. Specifically, they have different proportions of saturated, monounsaturated, and polyunsaturated fatty acids, which gives them distinct properties and nutritional profiles. 7. Cellulose is a polysaccharide found in plant cells. In which component of the plant cell is it found? Cellulose is found in the plant cell wall. 8. Which carbohydrate is found in: a) Potatoes and rice: Starch* b) Human blood: Glucose* 9. The equation below represents a reaction to the formation of a lipid molecule. Fatty acids + glycerol --A--> A triglyceride + water Identify the reaction labelled A in the word equation above. Reaction A is a condensation reaction* (or dehydration synthesis). State and explain three properties of enzymes. 1. Biological Catalysts: Enzymes speed up the rate of biochemical reactions without being consumed in the process. 2. Specificity: Each enzyme typically acts on a specific substrate or a small group of related substrates due to the unique shape of its active site. 3. Sensitivity to Temperature and pH: Enzymes have optimal temperature and pH ranges at which they function most efficiently. Extreme temperatures or pH levels can cause denaturation, altering their shape and reducing their activity. 10. Explain the importance of proteins in living organisms. Proteins are crucial for living organisms due to their diverse roles: Structural support*: Forming components like collagen in connective tissues and keratin in hair and nails. Enzymatic activity*: Acting as biological catalysts to speed up metabolic reactions. Transport*: Carrying substances (e.g., hemoglobin transports oxygen) and forming channels in cell membranes. Defense*: Antibodies are proteins that protect the body from pathogens. Hormonal regulation*: Some hormones (e.g., insulin) are proteins that regulate physiological processes. Movement*: Actin and myosin proteins are essential for muscle contraction. 11. Explain the importance of proteins in living organisms. (This is a repeat of question 10. The answer provided for question 10 covers this.) 12. a) What is a substrate? A substrate is the specific molecule upon which an enzyme acts. It binds to the enzyme's active site, where the reaction takes place. 12. b) How does substrate concentration affect enzyme activity in reactions occurring in the cells? As substrate concentration increases, enzyme activity generally increases because more substrate molecules are available to bind to the enzyme's active sites. This continues until all active sites are saturated with substrate, at which point the enzyme activity reaches its maximum rate (Vmax) and further increases in substrate concentration will not increase the reaction rate. 13. You are tasked with designing a balanced diet plan for a community using locally available foods. Propose a combination of foods that ensures adequate intake of proteins, carbohydrates, lipids and vitamins. A balanced diet plan using locally available foods could include: Proteins: Beans, lentils, groundnuts, eggs, local fish, chicken.* Carbohydrates: Maize meal (ugali/sadza), rice, sweet potatoes, cassava, yams, bananas.* Lipids: Avocado, groundnuts, sunflower oil, palm oil (used in cooking).* Vitamins and Minerals: Leafy green vegetables (e.g., spinach, kale), carrots, tomatoes, oranges, mangoes, papayas.* 14. Read and make notes on Chemicals of Life This is an instruction for the student to perform a task, not a question to be answered.