1.11 An important component of chlorophyll ... A phosphorus B nitrogen C sulphur D iron 1.12 Calcium is used by humans to prevent ... A beri-beri B soft bones C anaemia . D goitre 1.13 A symplom of rickets is ... A bleeding gums B poor night vision C bone deformity / D swollen thyroid gland 1.14 An organic molecule is ... A salt B water . C carbon dioxide D starch . 1.15 The main source of energy for humans is ... A proteins

Sure, I'd be happy to help answer these multiple-choice questions. Here's a breakdown of each question with the correct answers and brief explanations: --- **1.11 An important component of chlorophyll ...** **Options:** - A) Phosphorus - B) Nitrogen - C) Sulphur - D) Iron **Answer:** **B) Nitrogen** **Explanation:** Chlorophyll is the green pigment essential for photosynthesis in plants. It primarily contains magnesium at its center, but among the given options, nitrogen is a key component of chlorophyll's molecular structure, particularly in the porphyrin ring. --- **1.12 Calcium is used by humans to prevent ...** **Options:** - A) Beri-beri - B) Soft bones - C) Anaemia - D) Goitre **Answer:** **B) Soft bones** **Explanation:** Calcium is crucial for maintaining strong and healthy bones and teeth. It helps prevent conditions like osteoporosis, which is characterized by weak and soft bones. --- **1.13 A symptom of rickets is ...** **Options:** - A) Bleeding gums - B) Poor night vision - C) Bone deformity - D) Swollen thyroid gland **Answer:** **C) Bone deformity** **Explanation:** Rickets is a disease that affects bone development in children, leading to soft and weak bones. This can result in bone deformities such as bowed legs or thickened wrists and ankles. --- **1.14 An organic molecule is ...** **Options:** - A) Salt - B) Water - C) Carbon dioxide - D) Starch **Answer:** **D) Starch** **Explanation:** Organic molecules contain carbon and are typically found in living organisms. Starch is an organic carbohydrate made up of glucose units. In contrast, salt (inorganic), water (inorganic), and carbon dioxide (inorganic) do not fall under organic molecules. --- **1.15 The main source of energy for humans is ...** **Options:** - A) Proteins - *[Options B, C, D not provided]* **Answer:** **(Assuming typical options)** If the typical options are: - A) Proteins - B) Carbohydrates - C) Fats - D) Vitamins **The likely answer would be:** **B) Carbohydrates** **Explanation:** Carbohydrates are the primary source of energy for humans. They are efficiently broken down into glucose, which is used by the body's cells for energy. While proteins and fats can also provide energy, they are generally secondary sources. *Please provide the complete set of options for question 1.15 if you need a more accurate answer.* --- Feel free to ask if you have more questions or need further explanations!