booklet 2

• There are 4 main types of tissue in plants: tissues for protection, strength and support, transport, and storage
• Tissue - group of identical cells that function together to carry out a particular function
• PROTECTION - Epidermis

  • A continuous layer of transport cells that cover the surface
  • Protection against the entry of bacteria and excessive loss of water
  • They have no chloroplast
  • Function - to let light pass through them
  • Tightly packed together (no intracellular spaces)
  • Only one cell thick
• Stems - covered with a waxy cuticle to prevent infection and dehydration

  Leaves - covered with a waxy cuticle to prevent infection and dehydration. Pores (stomata) allow for CO2 to enter (PSN)

  Roots - extended to the root hairs to increase the surface area - maximum absorption of water and minerals
• STRENGTH AND SUPPORT - Collenchyma and Sclerenchyma

  Collenchyma

  • Living tissue
  • Allows for flexibility in plants
  • Thick cellulose walls, especially thick at corners - offers support to plants
  • The petiole (leaf stalk) usually has collenchyma for strength and support

  Sclerenchyma

  • Non-living tissue
  • Allows for flexibility in plants
  • Lined with lignin around whole edge
  • Cells die after cell wall is fully formed - cells become hollow
  • Once cells hollow out - no water due to lignin and therefore cells turn to wood
• TRANSPORT - Xylem and Phloem


  Xylem

  • Dead cells
  • Thick cell wall
  • Cell wall is made of lignin
  • Non-permeable
  • No cytoplasm
  • Transports water and dissolved mineral salts to leaves
  • Direction of flow in plants is up
  • Tissue also has fibres
  • Found in veins of plants

  Phloem

  • Living cells
  • Thin cell wall
  • Cell wall is made of cellulose
  • Permeable
  • Cytoplasm is present
  • Transports food/organic compounds to growing parts and storage organs of plants
  • Direction of flow in plants is up and down
  • Tissue also has companion cells !!NB!!
  • Found in veins of plants
• STORAGE - Parenchyma

  • Roundish, thin-walled cells used as packing tissue
  • Cells are very metabolically active and allows rapid movement of water across them; may sometimes be used for storing carbohydrates (eg. make up edible part of fruit)
  • When the cells are turgid (fully inflated with water) they help to support the plant, preventing wilting
  • Air spaces between the cells allow for gaseous exchange. Water and mineral salts are transported through the living contents of the cells
• GROWTH - Meristematic tissue

  • Unspecialised tissue found in growing regions of the plant
  • Shoot tips and root tips (increased growth of stems and roots)
  • Cells are cube-like and densely packed
• • Respiration is the release of energy from food substances.

  • Respiration takes place in ALL LIVING CELLS (plants and

  animals).

  • Makes use of OXYGEN
• Aerobic RSP – when oxygen is freely available

  Anaerobic RSP – when oxygen is not available.
• RSP occurs in the cells of every living organism (all the time) and the energy

  that is produced is used for:

  • 1. Maintaining a constant body temperature

  • 2. Growth – the repair of tissues

  • 3. Active transport

  • 4. Movement
• THE ENERGY STORE OF THE CELL – ATP

  • RSP is the release of energy – this energy is not used

  directly by the cell.

  • The energy is transferred to other substances which act as

  a store of energy for the cell.

  • One of these substances is ATP (Adenosine Triphosphate).
• Aerobic RSP – Oxygen is AVAILABLE

  • High energy food molecules react with oxygen and become

  OXIDISED.

  • During the process, the food molecules (glucose) are completely

  broken down into carbon dioxide, water, heat and ATP.
• aerobic respiration

  
• PSN

  Raw Materials: Water and Carbon

  Dioxide

  Products: Glucose and Oxygen

  RSP

  Raw Materials: Glucose and Oxygen

  Products: Water and Carbon Dioxide

  they are Inter-Linked!!
• THE MITOCHONDRION

  • RSP takes place in the mitochondria.

  Specialised for RSP:

  • Double membrane (semi-permeable)
  • Folds in the membrane – Cristae
  • Crista have Enzymes (ATP synthesis)
  • Dense matrix – filled with a solution that contains

  enzymes to speed up reactions

  A) matrix

  B) outer membrane

  C) Ribosome

  D) Cristae

  E) Inner membrane

  F) DNA

  
• PRODUCTION OF ATP = Glycolysis OR Krebs Cycle

  GLYCOLYSIS

  • Glycolysis takes place in the cytoplasm.

  • During this stage glucose (6-carbon molecule) is broken down into two

  smaller molecules called pyruvate (3-carbon molecule) and a small amount of ATP.

  
• KREBS CYCLE

  • The Krebs cycle takes place in the mitochondrion.

  • In the presence of oxygen, the pyruvate molecules produced during

  glycolysis break down to form carbon dioxide and water, and a larger

  amount of ATP is produced.