1. It helps in the storage of water and several other substances, namely food, waste products and pigments. It also provides turgidity to the cell.   Hint Hint       2. It provides shape to the cell. It is semi-permeable, regulating the entry and exit of substances, namely solutes and ions.   Hint       3. It provides protection, shape and rigidity to the cell. It is freely permeable, allowing substances in the form of solutions to enter and leave the cell without any hindrance.   Hint       4. It synthesizes and secretes certain substances, namely hormones and enzymes. It also helps in the formation of acrosome of sperm.   Hint       5. It is the site of ATP (Adenosine triphosphate) synthesis. It also synthesizes respiratory enzymes.   First letter clue   6. It is a plastid, containing pigments such as xanthophyll (yellow in color) and carotene (orangish-red in color). These pigments impart color to flowers and fruits of plants.   First letter clue   7. It initiates and regulates cell division. It also helps in forming spindle fibres, with the help of asters.   First letter clue