Plants

• What are some important plant tissues?

  • epidermal tissues
  • palisade mesophyll
  • spongy mesophyll
  • xylem and phloem
  • meristem tissue found at the growing tips of shoots and roots
• What's the waxy cuticle?

  Protective layer on top of the leaf which prevents water from evaporating
• What is the upper epidermis?

  Thin and transparent to allow light to enter palisade mesophyll layer underneath it
• What is the palisade mesophyll?

  Column shaped cells tightly packed with chloroplasts to absorb more light, maximising photosynthesis
• What is the spongy mesophyll?

  Contains internal air spaces that increases the surface area to volume ratio for the diffusion of gases(mainly carbon dioxide)
• What is the lower epidermis?

  contains guard cells and stomata
• What are the guard cells?

  Absorbs and loses water to open and close the stomata to allow carbon dioxide to diffuse in, oxygen to diffuse out
• What is the stomata?

  • where gas exchange takes place
  • opens during the day, closes during the night, evaporation of water also takes place from here
  • in most plants, found in much greater concentration on the underside of the leaf to reduce water loss
• what is a vascular bundle?

  contains xylem and phloem to transport substances to and from the leaf
• what is xylem?

  transports water into the leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
• what is phloem?

  transports sucrose and amino acids around the plant
• what is the leaf adapted for?

  specifically photosythesis
• what is the adaptation of large surface area?

  increases surface area for diffusion of carbon dioxide and absorption of light for photosythesis
• what is the adaptation of thin?

  allows carbon dioxide to diffuse to palisade mesophyll cells quickly
• what's the adaptation of chlorophyll?

  absorbs light energy so that photosynthesis can take place
• what's the adaptation of network of veins?

  allows the transport of water to the cells of the leaf and carbohydrates from the leaf for photosynthesis(water for photosynthesis, carbohydrates as a product of photosynthesis)
• what's the adaptations of the stomata?

  allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out
• what is the adaptation of the epidermis being thin and transparent?

  allows more light to reach the palisade cells
• what's the adaptations of thin cuticle and made of wax?

  to protect the leaf without blocking sunlight
• what are the adaptations of the palisade layer at the top of the leaf?

  maximises the absorption of light as it will hit chloroplasts in the cells directly
• what are the adaptations of air spaces in the spongy layer?

  air spaces allow the carbon dioxide to diffuse through the leaf, increasing the surface area
• what are the adaptations of vascular bundle?

  thick well walls of the tissue in the bundles help to support the stem and leaf
• what's the pathway of co2 molecule when the leaf is photosynthesis?

  1. higher concentration of co2 in atmosphere compared to inside the leaf
  2. co2 diffuses into leaf through open stoma into air space in spongy mesophyll
  3. co2 diffuses through cell wall and cell membrane of mesophyll cell, dissolves in cytoplasm and diffuses into chloroplast
• What does the structure of a leaf maximise?

  the diffusion of carbon dioxide into the mesophyll cells for photosynthesis
• what does the structure of the leaf enable?

  air to circulate within it to maximise the diffusion of carbon dioxide to the chloroplasts for photosynthesis
• Plant Organs

  • The structure of root hair cells, xylem and phloem are adapted to their functions
  • The roots, stem and leaves are all plant organs that form a plant organ system for transport of substances around the plant
• What are the two types of transport vessels in plants?

  Xylem and phloem
• What is the primary function of xylem vessels?

  Transport water and minerals from roots
• How are xylem vessels adapted for their function?

  They are hollow tubes strengthened by lignin
• What is the main function of phloem vessels?

  Transport food materials from leaves
• What types of food materials do phloem vessels mainly transport?

  Sucrose and amino acids
• Where do phloem vessels transport food materials from?

  From photosynthesising leaves
• What are vascular bundles?

  Groups of xylem and phloem vessels
• Where are xylem and phloem vessels arranged in plants?

  Throughout the root, stem, and leaves
• What are the functions of xylem and phloem in plants?

  • Xylem:
  • Transports water and minerals from roots to leaves
  • Composed of hollow tubes strengthened by lignin
  • Phloem:
  • Transports food materials (sucrose, amino acids) from leaves to non-photosynthesising regions
  • Arranged in vascular bundles throughout the plant
• • Root hair cells are adapted for the efficient uptake of water by osmosis, and mineral ions by active transport
  • Root hairs are single-celled extensions of epidermis cells in the root which increase the surface area of the cells significantly; this increases the rate of the absorption of water by osmosis and mineral ions by active transport
  • They grow between soil particles and absorb water and minerals from the soil
  • Water enters the root hair cells by osmosis
  • This happens because soil water has a higher water potential than the cytoplasm of the root hair cell
• what does the structure of the root maximise?

  absorption of water by osmosis and mineral ions by active transport
• what does osmosis cause water to do?

  osmosis causes water to pass into the root hair cells, through the root cortex and into the xylem vessels
• what's the pathway of water into and across a root

  • once water gets into the xylem, it is carried up to the leaves where it enters the mesophyll cells
  • root hair cell ->root cortex cells->xylem->leaf mesophyll cells
• What is transpiration?

  Loss of water vapour from plant leaves