cells ✦

• cytoplasm: site of most cellular activities
• cell surface membrane: controls movement of substances
• cell surface membrane is made out of proteins & lipids
• vacuole: stores water & food substances
• nucleus: controls cellular activities
• mitochondria - site of aerobic respiration
• mitochondria is small elongated organelles with folded inner membranes
• aerobic respiration: process in which energy is extracted from food substances in the presence of oxygen
• energy from mitochondria is used to perform cellular activites
• chloroplast: contains chlorophyll
• chlorophyll: absorbs light energy & converts it into chemical energy to form glucose for photosynthesis
• cell wall: protects & gives fixed shape of the cell
• red blood cell: contains haemoglobin which binds reversibly to oxygen & transports it around the body
• red blood cell: has a circular, biconcave shape which increases the surface area-to-volume ratio so that oxygen can diffuse in and out at a faster rate
• red blood cells: lacks a nucleus, enabling the cell to store more haemoglobin to transport more oxygen
• red blood cell: is flexible and can squeeze through capillaries easily
• muscle cell: is elongated & cylindrical in shape, contains many nuclei and mitochondria
• muscle cell has mitochondria to provide the energy for the contraction of muscle cell
• root hair cell has a long narrow root hair to increase the surface area-to-volume ratio to absorb water by osmosis and mineral salts by diffusion & active transport at a faster rate from soil solution
• root hair cell absorbs water via osmosis
• root hair cell absorbs mineral salts via diffusion & active transport
• root hair cell contains many mitochondria to release high amount of energy during aerobic respiration to allow cell to absorb mineral salts from soil to root hair cell via active transport
• root hair cell has concentrated cell sap to maintain a steep water potential gradient for absorption of water molecules from soil into the cell by osmosis