Transport on plants-xylem

• What is the primary function of xylem in plants?

  Xylem transports water and minerals from the roots to the leaves.
• What are the two types of tissue involved in transport in plants?

  • Xylem: transports water and minerals
  • Phloem: transports organic substances
• What do xylem vessels consist of?

  Xylem vessels are long tube-like structures formed from dead cells.
• How do xylem vessels facilitate water transport?

  They have no end walls, allowing water to pass through easily.
• What forces help water move up a plant against gravity?

  Cohesion and tension help water move up against gravity.
• What is transpiration in plants?

  Transpiration is the loss of water from a plant's surface, especially the leaves.
• What happens to water during transpiration?

  Water evaporates from the moist cell walls and accumulates in the spaces between cells in the leaf.
• How does the opening of stomata affect transpiration?

  When stomata open, water moves out of the leaf down the concentration gradient.
• What are the four main factors that affect transpiration rate?

  1. Light: More light increases transpiration rate.
  2. Temperature: Higher temperatures increase transpiration rate.
  3. Humidity: Lower humidity increases transpiration rate.
  4. Wind: More wind increases transpiration rate.
• How does light intensity affect transpiration rate?

  Higher light intensity leads to a faster transpiration rate due to stomata opening for photosynthesis.
• How does temperature influence transpiration rate?

  Higher temperatures increase the energy of water molecules, leading to faster evaporation.
• What is the relationship between humidity and transpiration rate?

  Lower humidity increases the transpiration rate due to a greater concentration gradient.
• How does wind affect transpiration rate?

  Increased wind speed enhances transpiration by blowing away water molecules.
• How can a potometer be used in experiments?

  • Estimates transpiration rate based on water uptake.
  • Measures the distance moved by an air bubble in a capillary tube.
  • Helps assess the impact of different environmental factors on transpiration.
• What are the steps to dissect a plant for examining xylem and phloem?

  1. Cut a shoot underwater to prevent air entry.
  2. Assemble the potometer and insert the shoot underwater.
  3. Ensure the apparatus is watertight and airtight.
  4. Dry the leaves and allow acclimatization.
  5. Record the starting position of the air bubble.
  6. Measure the distance moved by the bubble over time.
• What is the purpose of staining plant sections with toluidine blue O (TBO)?

  TBO stains the lignin in the walls of the xylem vessels blue-green for visibility.
• What should be done to the cut sections of the plant before using them under a microscope?

  Place the cut sections in water to prevent them from drying out.
• How does the cohesive-tension theory explain water movement in plants?

  The cohesive-tension theory explains that water molecules stick together (cohesion) and are pulled up through the xylem by tension created during transpiration.
• What is the main role of phloem in plants?

  Phloem transports organic substances throughout the plant.
• What is the significance of the air bubble movement in a potometer?

  The movement of the air bubble indicates the rate of transpiration.
• What should be kept constant when measuring transpiration rate using a potometer?

  All conditions except the one being tested (e.g., temperature) must be kept constant.
• What is the function of stomata in relation to transpiration?

  Stomata allow water vapor to exit the leaf, facilitating transpiration.
• How does transpiration contribute to nutrient transport in plants?

  Transpiration creates a negative pressure that helps pull water and dissolved nutrients from the roots to the leaves.
• How does the structure of xylem vessels relate to their function?

  The structure of xylem vessels, being long and without end walls, allows for efficient water transport.