plant structure

• list the structural components of a plant.

  -flower

  -leaf

  -stem

  -root

  -root hairs

  
• describe the function of the flower.

  contains the male and female sex organs of the plant. they produce seeds.

  the flower is usually brightly coloured and scented to attract insects for pollination.
• describe the function of the leaf.


  the organ for photosynthesis. it absorbs light and converts this into food for the plant
• describe the function of the stem


  holds the plant upright. it contains vascular bundles.
• describe the function of the root.

  the main job of the root is to anchor the plant in the soil. it takes up water and minerals from the soil
• describe the function of root hairs


  the place where water and minerals are absorbed from the soil. root hairs increase the surface area of the roots to make them more efficient
• what is the stem adapted to?


  -supporting the leaves and holding them up towards the sun

  -transporting food and water

  -provides storage

  -formation of buds, leaves and flowers
• what are the parts of the stem?


  -phloem

  -cambium

  -pith

  -cortex

  -xylem

  -epidermis
• describe the function of the phloem


  transports sucrose and amino acids
• describe the function of the xylem

  transports water and mineral ions
• describe the function of the cambium


  found as a circle around the inner stem and outer surface. forms a woody secondary tissue for support.
• describe the function of the pith

  large central area for support and storage
• describe the function of the epidermis


  thin layer of skin cells. offers protection
• describe monocot stems.


  vascular bundles are scattered throughout the ground tissue. the ground tissue of the monocot is usually not clearly separated into the pith and cortex
• describe the dicot stems


  vascular bundles form a ring that divides the ground tissue into the cortex and the pith. the pith is located at the centre of the stem.
• label the following stems. which one is monocot and which is dicot?

  left (blue) = monocot

  right (green) = dicot

  A) vascular bundles

  B) pith

  C) cambium

  D) vascular bundles

  E) cortex

  F) epidermis

  
• describe the function of the roots.


  absorb and transport water and mineral ions

  anchor plant in soil

  roots allow storage of water and carbohydrates
• label the leaf

  .

  A) margin

  B) midrib

  C) lamina

  D) petiole

  E) vein

  
• describe the function of each internal component of the leaf


  -waxy cuticle: transparent later which prevents water loss by evaporation

  -epidermis: single layer of cells on the upper and lower surface of the leaves. the epidermis protects the plant and reduces evaporation.

  -palisade mesophyll layer: containing long cells which contain a lot of chloroplasts. this is the site of photosynthesis as it receives the most light.

  -spongy mesophyll layer: allowing gases such as carbon dioxide to circulate through.
• label the following diagram.

  .

  A) cuticle

  B) upper epidermis

  C) palisade mesophyll

  D) spongy mesophyll

  E) guard cells

  F) stoma

  
• Xylem


  Special cells made by the vascular cambium which soon die, losing their cytoplasm and nucleus as well as the walls and their ends so they can then conduct water and minerals
• Phloem

  Cells have companion cells which are alive
• Xylem cells

  1. Ends dissolve

  2. Several xylem cells make a continuous tube
• Xylem cells


  • Coils of lignin (component of wood) added for strength to prevent walls from collapsing
  • Openings in the side allow transfer of water to nearby xylem or cells
• Companion cells


  Cells near the phloem that helps keep the sieve tube alive
• Sieve tube cells


  Make up vessels of phloem, lose most of their organelles but are still alive
• Sieve plate


  • Tiny holes at the end of the sieve tube cells to allow passage of sugar solutions