Chapter 1 Biology

• Permanent tissues


  Matured tissues that have already undergone differentiation or are currently undergoing differentiation process
• Types of permanent tissues

  • Epidermis tissues
  • Ground tissues
  • Vascular tissues
• Epidermis tissues


  • Found on the outer surface of stems, leaves and roots of young plants
  • Epidermal wall exposed to outer environment has a layer of waxy and waterproof cuticle
  • Cuticle helps to minimize water loss through evaporation (transpiration), provide protection and prevent entry of pathogens
  • Modified epidermal cells include guard cells and root hair cells
• Guard cells


  Control the opening and closing of stoma for photosynthesis
• Root hair cells


  Help to increase the surface area for absorption of water and mineral salts
• Ground tissues


  • Parenchyma tissues
  • Collenchyma tissues
  • Sclerenchyma tissues
• Parenchyma tissues


  • Simplest living cells that are not differentiated yet
  • Cell walls are thin
  • Arranged in a turgid state to provide support and maintain the shape of herbaceous plants
  • Carry out photosynthesis and store starch and glucose
  • Involved in gaseous exchange
  • Involved in the repair and regeneration of plant tissues as well as transport of vascular system
• Collenchyma tissues


  • Living cells which become flexible upon maturation
  • Cell walls are made up of pectin and hemicellulose
  • Cell wall is thicker than the cell wall of parenchyma cell
  • Give mechanical support and elasticity to the plants
• Sclerenchyma tissues


  • Made up of matured dead cells
  • Cell walls are the thickest
  • Support and strengthen matured parts of the plant
  • Help in the transport of water and nutrients
• Vascular tissues


  • Xylem
  • Phloem
• Xylem


  • Made up of dead cells without cytoplasm
  • Cell walls contain lignin
  • Made up of hollow xylem vessels that extend from the roots to the leaves
  • Transport water and mineral salts from the roots to other parts of the plant
• Phloem


  • Made up companion cells and sieve tubes (living cells that contain cytoplasm)
  • Sieve tubes do not have nucleus and ribosomes due to decomposition after maturation
  • Sieve tubes are continuous arranged from end to end
  • Phloem transports glucose formed from photosynthesis from the leaves to the roots, fruits and tubers to be stored
• Meristematic tissues


  Undifferentiated living tissues involved in plants growth
• Types of meristematic tissues

  • Apical meristems
  • Lateral meristems
• Apical meristems


  Found at the tips of plant shoots and roots
• Lateral meristems


  Made up of vascular cambium and cork cambium
• Growth and development


  Changes that happen in an organism from zygote stage to an adult
• Zones of cell growth at the tips of shoots and roots

  • Zone of cell division
  • Zone of cell elongation
  • Zone of cell differentiation
• Zone of cell division

  Take place at the apical meristems where meristem cells are actively dividing by mitosis
• Zone of cell elongation


  Made up of cells that are increasing in size through absorption of water by osmosis and nutrients
• Zone of cell differentiation

  Consist of differentiated cells that reach their maximum size and carry out specific functions
• Types of growth in plants

  • Primary growth
  • Secondary growth
• Primary growth


  Undergone by all plants, happens after germination to increase the length of stem and roots, takes place at the apical meristems
• Secondary growth


  Occurs mostly in eudicots and some monocots, helps the plant to increase the circumference or diameter of the stem and root, results from the division of lateral meristem cells
• Secondary growth


  1. Cell division at the vascular cambium

  2. Formation of new xylem and phloem tissues

  3. Compression of primary xylem towards the pith

  4. Formation of cork cells by cork cambium
• The different formation of secondary xylem can be used to determine the age of a tree
• Necessity of primary growth

  Enables the elongation of plants to obtain maximum sunlight, transports photosynthesis products and water/minerals, provides mechanical support
• Necessity of secondary growth

  Stabilizes the plants, provides mechanical support, produces more xylem and phloem tissues, replaces older and damaged tissues, produces stronger and thicker bark
• Similarities between primary and secondary growth in eudicots

  • Both increase the size of plants permanently
  • Both occur in woody plants
  • Both involve cell division via mitosis
• Differences between primary and secondary growth in eudicots

  • Meristem tissue involved
  • Parts of the plant that undergo growth
  • Direction of growth
  • Growth effects
  • Tissues and structures formed
  • Presence of woody tissues
  • Thickness of bark
  • Presence of annual growth rings
• The economic importance of plants that have undergone secondary growth includes producing timber, resin and oil, and generating income from fruits and decorative plants
• Annual plants


  Plants that have only one life cycle for a season or a year. Normally die after completing their biological cycle, from germination to flowering or production of seeds
• Annual plants


  • paddy
  • pumpkin
  • watermelon
• Biennial plants


  Plants that need 2 years with 2 seasons of growth to complete their life cycle. The first growth season is the vegetative growth where the roots, leaves and stems grow. The second growth season is reproduction
• Biennial plants


  • cabbage
  • carrot
  • silver cock's comb
• Perennial plants


  Plants that live more than 2 years. Long lifespan (depends on the types of species and environmental conditions). Can be categorized into woody perennial plants and herbaceous perennial plants. Most of the plants can produce flowers and bear fruits many times throughout their lives. Can adapt to the environment and changes in the surrounding temperature
• Perennial plants


  • grass
  • hibiscus plant
  • mango plant
• Growth curve of annual plants

  1. Decreasing dry mass (stored food in cotyledon used for germination)

  2. Increasing dry mass (rapid growth with photosynthesis)

  3. Constant dry mass (maturity reached)

  4. Decreasing dry mass (aging, low photosynthesis, shedding leaves, seed dispersal)
• Growth curve of biennial plants

  1. First growth season (produce leaves, carry out photosynthesis, store food in tubers)

  2. Second growth season (use stored food to produce flowers and seeds)
• Growth curve of perennial plants


  Series of small sigmoid curves (high growth rate in spring/summer, low growth rate in winter)