PLANT STRUCTURE: ROOTSTYPES & PARTS OF THE ROOT • Tap roots - is a single main root with smaller lateral roots growing from it • Adventitious roots – roots which grow straight out of the stem eg. Carillie • Fibrous roots – several main roots, which have lateral or side roots branching from them • At the very tip – the root cap which protects the root as it grows • A layer of cells called the epidermis • The root hairs
ROOT FUNCTIONS • a) take in water from the soil; • b) take in minerals; • c) store excess food; • d) transport water and food to other parts of the plant; and • e) hold or anchor the plant in the soil
HOW DOES ROOTS TRANSPORT WATER • Root hairs absorb water by osmosis • Osmosis is the movement of particles (in this case: water and minerals) from a region of high concentration to a region of low concentration • And the water moves up the root into the XYLEM vessels (it acts like capillary tube) because of a pressure difference • The pressure difference happens because water evaporates from the leaves at the top (so it makes a lower pressure)…this is called transpiration
HOW DOES THE ROOT TRANSPORT MINERALS • The minerals the plants need is dissolved in the water (in the form of ions) • Special carrier molecules in the cell membrane, gets (a lot of) energy from the mitochondia in the root hairs and carries the mineral ions from a lower concentration outside of the root to the inside of the root …called ACTIVE TRANSPORT
HOW ARE THE ROOTS USED TO STORE FOOD? • The plants stores food for use later on • Perennial plants are those that live from year to year, have modified roots (swollen) called Root Tubers such as cassava and sweet potato and • Swollen Tap Roots for Biennial plants (which take two years to complete their life) such as carrots, beets and radishes.
STEMS • a) support the plant; • b) expose the leave to sunlight; • c) transport food and water to other parts of the plant; and • d) sometimes, photosynthesis (food) is made in the stem
LEAVES • a) take in carbon dioxide; • b) release oxygen (the exchange of gases.....taking carbon dioxide into the leaves and releasing oxygen out of the • leaf...... is referred to as respiration); • c) chlorophyll; • d) photosynthesis; and • e)take in energy from the sun
FLOWERS • a) Flowers perform sexual reproduction occurs for the formation offspring • Some plants reproduce using other parts of the plant like the stem (cassava), roots (ginger), etc. For home-work determine the special name for this type of reproducion and
ASSESSMENT • Fill in the blanks: • A root has a _ _ _ called a _ _ _ _ _ _ _ and _ _ _ _ _ _ _ _ _. • There are 3 types of roots: _ _ _ roots, adventitious _ _ _ _ _ and _ _ _ _ _ _ _ roots. • Answer true (T) or false (F) for the following: • Plants take in water and minerals from the soil through its roots • Roots uses excess food • Leaves transport water and food to the roots • Roots hold or anchor the plant in the soil • Plants get minerals by a process called active transport • Answer the following: • Can plants store food for later on? If so give some examples of plants that store food in its roots. • Can plants be modified to produce root tubers earlier than one year for example? State any changes you know of.