Ib Topic 9 - Plant Science
Topic 9: Plant Science
9.1 Plant Structure and Growth
9.1.1
Draw and label plan diagrams to show the distribution of tissues in the stem and leaf of a dicotyledonous plant.
Cross-section of a stem Part of plant | Purpose | Epidermis | Surface of the stem made of a number of layers often with a waxy cuticle to reduce water loss | Cortex Tissue | Forming a cylinder of tissue around the outer edge of the stem. Often contains cells with secondary thickening in the cell walls which provides additional support | Vascular bundle | contains xylem, phloem and cambium tissue | Xylem | a longitudinal set of tubes that conduct water from the roots upward through the stem to the leaves | Phloem (sieve elements) | transports sap through the plant tissue in a number of possible directions | Vascular cambium | is a type of lateral meristem that forms a vertical cylinder in the stem. The cambium produces the secondary xylem and phloem through cell division in the vertical plane |
In the centre of the stem can be found the pith tissue composed of thin walled cells called parenchyma. In some plants this section can degenerate to leave a hollow stem.
Leaf Structure Part of plant | Purpose | Cuticle | Is a waxy layer which reduces water loss through the upper epidermis | Upper epidermis | Is a flattened layer of cell that forms the surface of the leaf and makes the cuticle | Palisade Layer | This is the main photosynthetic region of the leaf | Vascular bundle | Contains the transport system and vascular meristem tissue (x-xylem, p-phloem) | Spongy mesophyll | Contains spaces that allows the movement of gases and water through the leaf tissue | Lower epidermis | Bottom surface layer of tissues which contains the guard cells that form each stoma |
9.1.2
Outline three differences between the structures of dicotyledonous and monocotyledonous plants Feature | Monocotyledoneae | Dicotyledoneae | Embryo | One Cotyledon (seed leaf) | Two
9.1 Plant Structure and Growth
9.1.1
Draw and label plan diagrams to show the distribution of tissues in the stem and leaf of a dicotyledonous plant.
Cross-section of a stem Part of plant | Purpose | Epidermis | Surface of the stem made of a number of layers often with a waxy cuticle to reduce water loss | Cortex Tissue | Forming a cylinder of tissue around the outer edge of the stem. Often contains cells with secondary thickening in the cell walls which provides additional support | Vascular bundle | contains xylem, phloem and cambium tissue | Xylem | a longitudinal set of tubes that conduct water from the roots upward through the stem to the leaves | Phloem (sieve elements) | transports sap through the plant tissue in a number of possible directions | Vascular cambium | is a type of lateral meristem that forms a vertical cylinder in the stem. The cambium produces the secondary xylem and phloem through cell division in the vertical plane |
In the centre of the stem can be found the pith tissue composed of thin walled cells called parenchyma. In some plants this section can degenerate to leave a hollow stem.
Leaf Structure Part of plant | Purpose | Cuticle | Is a waxy layer which reduces water loss through the upper epidermis | Upper epidermis | Is a flattened layer of cell that forms the surface of the leaf and makes the cuticle | Palisade Layer | This is the main photosynthetic region of the leaf | Vascular bundle | Contains the transport system and vascular meristem tissue (x-xylem, p-phloem) | Spongy mesophyll | Contains spaces that allows the movement of gases and water through the leaf tissue | Lower epidermis | Bottom surface layer of tissues which contains the guard cells that form each stoma |
9.1.2
Outline three differences between the structures of dicotyledonous and monocotyledonous plants Feature | Monocotyledoneae | Dicotyledoneae | Embryo | One Cotyledon (seed leaf) | Two