Plant Systems

• How are leaves adapted for gas exchange?


  Leaves are adapted to exchange oxygen and carbon dioxide and to reduce water loss.
• What structures in a leaf help carry out its function?

  • Waxy Cuticle
  • Epidermis
  • Spongy Mesophyll
  • Air Spaces
  • Stomata and Guard Cells
  • Veins (Xylem and Phloem)
• What is the role of the waxy cuticle in leaves?


  The waxy cuticle covers epidermis cells and reduces the evaporation of water from the leaf.
• What is the function of the epidermis in a leaf?


  The epidermis provides protection for the mesophyll cells and is transparent to allow light to reach the chloroplasts.
• What do stomata do in a leaf?


  Stomata are pores that allow gases to enter and exit the leaf.
• What is the role of guard cells in relation to stomata?


  Guard cells open and close the stomata to regulate gas exchange.
• What is the function of veins in a leaf?


  Veins provide support for the leaf and contain xylem and phloem tissues.
• What does xylem transport in a plant?


  Xylem transports water and minerals from the roots.
• What does phloem transport in a plant?


  Phloem transports nutrients up and down the plant.
• Why are leaves flat and broad?

  Leaves are flat and broad to increase sunlight absorption with a larger surface area.
• How does the palisade mesophyll contribute to photosynthesis?


  The palisade mesophyll is packed full of chloroplasts, capturing more sunlight for photosynthesis.
• What is the role of spongy mesophyll in a leaf?


  The spongy mesophyll contains a small number of chloroplasts and has air spaces for gas accumulation and movement.
• What is transpiration in plants?


  Transpiration is the movement of water through a plant and its evaporation from aerial parts like leaves.
• What factors affect the rate of transpiration?


  1. Light intensity: More light opens more stomata.
  2. Temperature: Higher temperatures increase kinetic energy and evaporation.
  3. Humidity: Increased humidity slows diffusion of water.
  4. Air flow: Wind moves water vapor away, increasing concentration gradient.
• What is stomatal density?


  Stomatal density is the number of stomata per unit area of a leaf.
• How can stomatal density be determined?


  Stomatal density can be determined using a microscope with an eyepiece graticule.
• What increases the reliability of quantitative data?


  Reliability of quantitative data is increased by repeating measurements.
• What is the purpose of calculating standard deviation or standard error?


  Standard deviation or standard error helps determine the reliability of data collected.
• Why is it important to carry out more replicates in experiments?


  More replicates provide greater confidence regarding the variation within data collected.
• How does the variability of biological material affect stomatal density measurements?


  Variability necessitates replicate trials to ensure accurate stomatal density measurements.
• What is a solution?


  A homogeneous mixture of a solvent and a solute
• What is a solute?


  A substance that dissolves in a solvent to form a solution
• What is a solvent?


  A substance in which a solute is dissolved to form a solution
• What is solvation?


  The interaction between a solvent and a solute
• How do water molecules interact with ionic compounds in solvation?


  Water molecules form hydration shells around the ions
• What happens to covalent compounds like glucose when dissolved in water?


  They form intermolecular interactions with water molecules
• What is the definition of a hypertonic solution?


  A solution with a higher concentration of solutes compared to another solution
• What is the definition of an isotonic solution?


  A solution with the same concentration of solutes compared to another solution
• What is the definition of a hypotonic solution?


  A solution with a lower concentration of solutes compared to another solution
• In which direction do water molecules move in relation to hypotonic and hypertonic solutions?


  Water moves from a hypotonic solution to a hypertonic solution
• What are the effects of water movement on cells in different solutions?

  • Hypertonic solution: Plasmolysis occurs, causing the plasma membrane to shrink.
  • Isotonic solution: No net movement of water, dynamic equilibrium.
  • Hypotonic solution: Cells swell and may burst (cytolysis).
• What is osmoregulation?


  The maintenance of constant osmotic pressure in the fluids of an organism
• What is the role of contractile vacuoles in unicellular organisms?


  To remove excess water and prevent cytolysis
• What are intravenous fluids used for?


  To administer fluids directly into a person's vein
• What is the theme associated with reproduction in plants according to the study material?

  Continuity and Change
• What are the two types of reproduction discussed in the study material?

  Asexual and sexual reproduction
• What are the medical applications of isotonic solutions?


  • Organs harvested for transplants need to be surrounded by isotonic solutions.
  • Intravenous fluids are administered to maintain hydration and electrolyte balance.
• What is the significance of sexual reproduction in terms of genetic variation?


  It produces offspring with new gene combinations
• What is the role of meiosis in sexual reproduction?


  Meiosis breaks up parental combinations of alleles
• What is the term for the fusion of gametes?

  Fertilization