Biology transport in plants

• What are dicotyledonous plants characterized by?

  They have two seed leaves and a branching pattern of veins in the leaf.
• What is a meristem?

  A layer of dividing cells, specifically referred to as the pericycle in this context.
• What is the function of phloem in plants?

  Phloem transports dissolved assimilates.

  
• What does vascular tissue consist of?

  Cells specialized for transporting fluid by mass flow.
• What is the primary function of xylem?

  Xylem transports water and minerals.
• Why do plants need a transport system?

  To take substances and return waste to their environment.
• How do plants absorb water and minerals?

  Through their roots.
• What is the direction of water and soluble minerals in xylem?

  Water and soluble minerals travel upwards only.
• How do sugars travel in phloem?

  Sugars can move up or down in the phloem.

  
• What is the structure of a young root's vascular bundle?

  • Central core of xylem in the shape of an X
  • Provides strength to withstand pulling forces
  • Surrounded by phloem and cambium layers

  
• What is the surface area to volume ratio of vascular plants?

  Vascular plants have a small surface area to volume ratio.
• What is a problem that roots face in transport?

  Roots can easily get water from the soil but cannot contain sugar from the soil.
• What is a problem that leaves face in transport?

  Leaves can produce sugar but not water from the air.
• What is the role of lignin in xylem?

  Lignin is a waterproof molecule that impregnates the cell wall of xylem.
• How does lignin affect xylem cells?

  Lignin prevents collapse of xylem cells.
• What happens to xylem cells after they die?

  They leave a long column of hollow dead cells.
• What is the significance of the continuous column of dead xylem cells?

  It allows water to flow easily.
• What is the function of plasmodesmata?

  They are gaps in the cell wall that connect two cells.
• What are the pathways for water movement through plants?

  1. Apoplast: Pass through spaces in cells
  2. Symplast: Water enters through cytoplasm
  3. Vacuolar: Water enters and exits through vacuole
• What is the role of companion cells in phloem?

  Companion cells help load sucrose into sieve tubes.

  
• What are sieve tube elements?

  They are tubes in phloem tissue that carry sap up and down the plant.

  
• What is the importance of transpiration in plants?

  Transpiration helps transport useful minerals and maintain cell turgidity.
• What factors affect transpiration?

  Light intensity, temperature, relative humidity, water availability, number of stomata, and thickness of the waxy cuticle.
• What happens to plants when they lose turgidity due to transpiration?

  Plants wilt and can die.
• What is the pathway of water movement through a leaf?

  1. Water enters the leaf through xylem
  2. Moves via osmosis into spongy mesophyll
  3. Water evaporates from cell wall of spongy mesophyll
  4. Water moves out of open stomata
• What is the role of guard cells in transpiration?

  Guard cells regulate the opening and closing of stomata for gas exchange.
• What is root pressure?

  Root pressure is when the endodermis moves minerals into the xylem by osmosis, drawing water into the xylem.
• What is the function of the Casparian strip in the endodermis?

  The Casparian strip regulates the movement of water and minerals into the vascular system.
• How does temperature affect the rate of transpiration?

  Higher temperatures increase the rate of transpiration, while lower temperatures decrease it.
• How does relative humidity affect transpiration?

  Higher humidity decreases water loss, while lower humidity increases it.
• What happens to transpiration when water availability decreases?

  Transpiration decreases as stomata close to preserve water.
• What is the role of a porometer?

  A porometer measures the rate of water uptake as a leafy stem transpires.
• What is the significance of transpiration for plant cooling?

  Transpiration supplies water that evaporates to keep the plant cool.
• What is the role of xylem vessels in water transport?

  Xylem vessels carry water up the plant.
• What is the role of living parenchyma cells in xylem?

  Living parenchyma cells act as packing tissue in xylem.
• How does the structure of xylem vessels contribute to their function?

  Xylem vessels are made from dead cells and have narrow tubes to prevent the water column from breaking.
• What is the importance of the thin walls of xylem vessels?

  Thin walls allow for capillary action.
• What is the significance of bordered pits in xylem vessels?

  Bordered pits allow water to leave one vessel and pass to the next.
• What is the role of sieve plates in phloem?

  Sieve plates separate sieve tube elements in phloem tissue.
• How do companion cells support sieve tube elements?

  Companion cells provide ATP for the metabolic processes of sieve tube elements.