science term 2

• root hairs grow out of the surface of roots and provide a big surface so that water and minerals can be absorbed into the plant
• xylem vessels are the water transport system of the plant. they transport water from root hairs to the leaves.
• water for support: helps plant to stand upright/ more firm and strong. water is inside vacuole. the cells press on one another to make the plant firm and supported
• spaces between soil particles are filled with air and water particles
• minerals such as magnesium and nitrate are absorbed by plants
• after water has been absorbed into the root hair cell, it moves from the outside of the root towards the inside, into the xylem vessels in the centre of the root
• when water moves into the root hair cell, it passes though the cell wall, cell membrane and cytoplasm.
• loss of water vapour from leaves is called transpiration
• stomata is when the water vapour can diffuses out of the leaf
• the liquid water in the cell soaks into the cellulose cell wall, and then changes to water vapour - it evaporates. Then the water vapour diffuses out of the leaf though stomata.
• when water arrives at the leaf, it moves out of the xylem vessels and into the leaf cells. the cells that have chloroplasts use some of the water for photosynthesis
• why plants need water? - water for support, water for transport, water for cooling & water for photosynthesis
• plant collapses: wilted
• water for cooling: when water evaporates, it takes heat away with it, it cools the cell.
• water for transport: as water moves though the xylem vessels, it carries dissolved mineral salts. These mineral salts are then transported from the roots to all the other part of the plant
• water for photosynthesis: water is one of the reactants in photosynthesis, plants change water and carbon dioxide to glucose and oxygen
• excretion means getting rid of waste materials
• eg of excretion: carbon dioxide( where body cells make in respiration), urea(substance that is made in liver cells), excess water that is not needed by the body.
• excreting urea: when we eat food, any protein in food are broken down into smaller molecules inside the digestive system. These small molecules go into the blood and the blood transport them to the liver. If we have more protein then we need, the liver changes the small molecules into urea. Then is taken away from the liver in blood.
• the urea is removed from the blood by the kidneys in the excretory system aka renal system. As blood flows through the kidneys, the kidneys filter the blood, they remove all of the urea from it. it also remove excess water from blood. The urea dissolves in the excess water. This solution is then called urine.
• The urine made in each kidney flows down a tube called a ureter, this carries it to the bladder which can store it for a while. The urine can flow out of the bladder to the outside though another tube called the urethra.