General Biology

• Growth

  is an irreversible permanent increase in size of an organ or its parts or an individual cell.
• Plant Growth

  it involves metabolic processes that consume energy.
• All plants are descendants of the zygote (fertilized cell)
• the zygote develops into a mature plant through growth and differentiation forming roots, leaves, branches, flowers, fruits, and seeds. Then they eventually die.
• PLANT GROWTH, FROM SEED GERMINATION TO MATURITY, INVOLVES A COMBINATION OF CELLULAR RESPONSES AND MOLECULAR INTERACTION.
• The presence of root hair in some plants increases the surface for water absorption.
• Varies of plant cells depend on the amount of water present in their surroundings.

  • Hypertonic (Plasmolysis)
  • Isotonic (Flaccid)
  • Hypotonic (Turgid)
• The condition in which the cell wall is rigid and stretched due to the absorption of water is called turgidity. These cells are referred to as a turgid.
• The state in which the cell content is shrunken is called flaccidity. These cells are referred to as flaccid.
• Water

  is an essential requirement for plants survival.
• Water uptake

  allows plants to metabolically utilize the chemical compounds and micronutrients obtained from the surrounding soil.
• Root nodules occur in some plants that are called Fabaceae.
• Root nodules

  wherein nitrogen-fixing bacteria establish a symbiosis with the plant to convert nitrogen gas to ammonia.
• Fabaceae

  plants with root nodules
• example of plants with root nodules:

  • Kudzu
  • Clover
  • Soybeans
  • Alfalfa
  • Peanuts
• Ginger

  a specialed stem known as rhizome.
• Rhizome

  serve as storage of starch and protein, which permit perennial growth.
• The small flower of a bougainvillea is located at the center of the colorful specialized leaves.
• These specialized leaves are often in a shade of white, pink, or yellow to attract pollinators to the small flower at the center of these bracts.
• Prop roots

  are also specialized plant parts that we see in mangroves or bakawan.
• These prop roots function to anchor and support the mangrove on the regularly water-logged soil.
• Wilting occurs in non-woody plants when the rate of water loss is faster than the rate of absorption of water by the roots.
• Cells in the plants lose their turgidity (stiffness) and the plant droops.
• Transpiration

  is a process by which water is lost in the form of water vapor from the surface of a plant into the air by evaporation.
• Stomata are pores in the epidermis of the leaves and stems.
• A pair of bean-shaped guard cells bound each stoma.
• Stomata

  Open during day, close at night.
• Monocotyledons

  Stomata are found only in the lower epidermis of the leaf.
• Dicotyledons

  Stomata are found on both sides of the leaf.
• Water vapour is lost through the stomata. Gases such as oxygen and carbon dioxide diffuse in and out of the leaf through the stomata during photosynthesis and respiration.
• the stomata will close when transpiration exceeds water absorption.
• to estimate the transpiration rate of plant is to measure its loss in weight using a weight potometer.
• The rate of transpiration is affected by these factors :

  • NUMBER OF STOMATA
  • LIGHT
  • TEMPERATURE
  • HUMIDITY
  • WIND
• Number of stomata

  A greater number of stomata increases the rate of transpiration.
• Light

  stimulates the opening of stomata.
• Temperature

  Water molecules move faster in warm air.
• Humidity

  High humidity reduces water loss and decreases the rate of transpiration.
• An increase in wind speed increases the rate of transpiration.
• Wind

  It is because the movement of air carries away the water vapor from the stomata.
• The transport system in flowering plants consists of two conducting tissues, the xylem and the phloem.