Topic 6: Plant Structures & their Functions

• What are auxins in plants?

  A group of plant hormones that inhibit growth in roots and stimulate growth in shoot tips
• How do auxins affect plant tropisms?

  They are involved in directing plant growth towards or away from stimuli
• In what commercial products are auxins commonly used?

  Rooting powders and selective weedkillers
• What is biomass?

  The total mass of organic material in a specific area over a set period
• What is the role of ethene in plants?

  It stimulates ripening in fruit
• What do gibberellins regulate in plants?

  They regulate germination and flowering
• How can gibberellins be used commercially?

  To control flower and fruit formation or produce seedless fruits
• What is gravitropism?

  A plant's growth response to gravity
• What are guard cells responsible for?

  Controlling the rate of transpiration by changing shape
• What is the inverse square law in relation to light intensity?

  Light intensity is inversely proportional to the square of the distance from the light source

  
• What is lignin's function in plants?

  It strengthens the walls of xylem cells
• What is a limiting factor in biological reactions?

  A variable that limits the rate of a particular reaction
• What is the lower epidermis of a leaf?

  A layer of cells on the leaf’s lower surface that contains stomata and guard cells
• What is negative plant tropism?

  The growth of a plant away from a stimulus
• What is the palisade mesophyll layer's role in plants?

  It is the main photosynthetic tissue located below the upper epidermis
• Why does the palisade mesophyll layer contain a high concentration of chloroplasts?

  It receives the most light for photosynthesis
• What is phloem's function in plants?

  It transports sugars from the leaves to the rest of the plant in both directions
• What is photosynthesis?

  An endothermic reaction that converts light energy into chemical energy
• What is the overall equation for photosynthesis?

  6CO₂ + 6H₂O ⟶ C₆H₁₂O₆ + 6O₂
• What is phototropism?

  A plant's growth response to light
• What is plant tropism?

  The growth response of a plant to a stimulus
• What is positive plant tropism?

  The growth of a plant towards a stimulus
• Who are producers in an ecosystem?

  Photosynthetic organisms at the start of the food chain
• What are root hair cells specialized for?

  Uptake of water and minerals from the soil
• What are rooting powders used for?

  To stimulate the growth of roots in cuttings
• What is the spongy mesophyll layer's function?

  It is specialized for gas exchange and contains some chloroplasts for photosynthesis
• What are stomata?

  Small holes on the surface of a plant that control water loss and gas exchange
• What is translocation in plants?

  The movement of sugars and amino acids up and down a plant via the phloem
• What factors affect the rate of transpiration?

  Light intensity, temperature, and air flow
• What is the upper epidermis of a leaf?

  A layer of transparent cells that allows light to strike the palisade mesophyll tissue
• What is a vascular bundle?

  Part of the transport system in vascular plants consisting of xylem and phloem tissue
• What is the function of the waxy cuticle in plants?

  It reduces water loss from the surface of leaves
• What is the function of xylem in plants?

  It transports water and dissolved minerals from the roots to the leaves
• What are the main producers of food in ecosystems?

  Plants and algae
• What process do plants and algae use to synthesize food from sunlight?

  Photosynthesis
• What type of reaction is photosynthesis?

  Endothermic reaction
• Where does photosynthesis occur in plants?

  In chloroplasts
• What is the equation for photosynthesis?

  Light + carbon dioxide + water → glucose + oxygen

  
• What is the chemical symbol for carbon dioxide?

  CO₂
• What is the chemical symbol for water?

  H₂O