cells

• Each living cell consists of living material called protoplasm which is made up of cell membrane, cytoplasm, vacuole and nucleus.
• Protoplasm is jelly-like, containing mainly water and many other substances.
• The nucleus controls cell activities such as cell growth, repair and cell division and contains genetic materials.
• The cell membrane is a thin, partially permeable membrane that controls substances moving in and out of the cell.
• Cytoplasm is a gel-like substance which acts as a medium where most chemical activities of the cell occur and contains enzymes and organelles.
• Mitochondria are rod-shaped and are the site of aerobic respiration in the cell to release energy.
• Ribosomes are the site of protein synthesis in the cell.
• Vacuoles exist in animal cells temporarily to store food and water and in plant cells they are enclosed by the tonoplast (a membrane) and contain cell sap, which consists of water and dissolved substances such as sugar, mineral salts and amino acids.
• Root hair cells function to absorb water via osmosis and mineral salts via diffusion and active transport.
• Red blood cells are elastic and can turn bell-shaped to allow the cell to move/ squeeze through small blood vessels.
• Root hair cells contain a large vacuole with concentrated cell sap.
• Muscle cells contain many mitochondria to release a large amount of energy (through aerobic respiration), for contraction.
• Root hair cells are long and narrow protrusions/ extensions of an epidermal cell to increase surface area to volume ratio for faster absorption of water and mineral salts from soil.
• Root hair cells are living cells that provide energy from respiration for active transport.
• Root hair cells have a lower water potential, allowing absorption of water from the soil.
• Red blood cells contain haemoglobin to allow oxygen to bind with RBC to form oxyhaemoglobin.
• Red blood cells have a circular biconcave shape to increase surface area to volume ratio for faster diffusion of gases in and out of cell.
• Muscle cells are elongated and cylindrical in shape, contain many nuclei and mitochondria.
• Red blood cells lack a nucleus to contain more haemoglobin and hence transport more oxygen.
• The endoplasmic reticulum (ER) consists of smooth ER and rough ER which synthesizes fats and steroids and detoxifies harmful substances into harmless substances the cell.
• Animal cells have a cellulose cell wall, no chloroplasts, numerous small vacuoles, and one large central vacuole.
• Differentiation is the process by which a cell becomes specialised for a specific function.
• Ribosomes attached to its outer surface synthesize proteins for transport out of the cell.
• The Golgi apparatus modifies and packages substances made by the ER into vesicles for secretion out of the cell.
• Plant cells have a cellulose cell wall, chloroplasts, and one large central vacuole.
• A tissue is a group of similar cells which work together to perform a specific function.
• An organ system is made up of different organs working together to perform a main body function.
• When haemoglobin combines with oxygen, oxyhaemoglobin is formed.
• The cell wall, made of cellulose, is a fully permeable membrane that protects the cell from injury and gives the cell a regular shape.
• Red blood cells contain haemoglobin (red pigment) in the cytoplasm which transports oxygen from the lungs to all parts of the body.
• An organ is made up of different tissues working together to perform a particular function.
• A cell is the smallest working unit in a multicellular organism.
• Chloroplasts contain chlorophyll which traps light energy and are the sites where photosynthesis takes place, the conversion of light energy into chemical energy in glucose.