Bio Part 2

• Consequences of low Surface Area to Volume Ratio

  Reduced gas exchange, inefficient waste removal, and poor nutrient uptake can occur
• Volume of the Cell

  Reflects the demand of the cell : how much activity is taking place and how many resources are required
• Surface Area of the Cell

  Reflects the area over which particles have to move in/out of the cell
• Division of Labour

  -Multicellular organisms benefit from it

  -Cells can specialize and perform functions more efficiently
• Size


  -Multicellular organisms benefit from it

  -Single cell organisms are restricted in size due to surface area to volume limitations. Multicellular organisms however have complex transport systems allowing for the exchange of nutrients and waste
• Interdependence 


  -Multicellular organisms benefit from it

  -if one cell dies, it does not kill the entire organism
• multicellular organism hierarchy 


  Cells > Tissue > Organ > Organ System > Organism
• Root system structures and functions

  -Anchorage

  -Reproduction

  -Absorption
• Shoot Systems Structure and Functions

  -Reproduction

  -Photosynthesis

  -Support
• Parts of a plant that are the shoot system

  -Leaves

  -Stems

  -Flowers

  -Fruit
• Dermal Tissue 


  -The thick outer layer and is generally one cell thick

  -Protects the plant from disease

  -Is replaced by cork and bark in woody plants

  -Involved in gas exchange in the leaves

  -Often secretes a waxy substance known as the cuticle to prevent water loss
• Ground Tissue


  -The majority of the plant

  -Provides strength, support and storage

  -Location photosynthesis occurs

  -The tissue located between the dermal layers
• Vascular Tissue


  -Responsible for transportation of water, sugars, and nutrients

  -Contains the Xylem and Phloem
• Formula for Photosynthesis


  (6)CO2 + (6)H2O > (6)O2 + C6H12O2
• Xylem


  Transports water
• Phloem


  Transports sugars and other materials
• Guard Cells


  -open and close the stomata

  -Open when they swell up
• Mesophyll Tissue


  -Lots of chloroplasts which equals photosynthesis

  -Located middle of the leaf
• Xylem tissue


  Transport water up the plant
• Phloem Tissue


  Transport sugar and water down through the plant
• Function of the Stomata

  Oxygen and Carbon dioxide exchange as well as release of water
• Cohesion 


  Waters ability to attract to itself/ other water molecules
• Adhesion


  Waters ability to adhere/ attach to other surfaces
• Transpiration Pull


  -Evaporation from the leaves "pulls" water from the stomata

  -When water evaporates through stomata, the pressure drops in the leaf, which causes new water molecules to fill the space (think of suction)

  -Cohesion between water molecules create a chain of water molecules that pulls through the xylem vessel

  -Adhesion to the side walls of the xylem helps plants counteract the force of gravity
• Root Pressure


  -Minerals are moved into the root from the soil using active transport

  -The root is hypotonic to the soil, and so water moves into the root through osmosis

  -As the roots swell due to osmosis, there is increasing pressure in the root, forcing water into the xylem
• Pressure Flow Theory

  -An area of a plant that stores sugar is known as a sugar sink

  -Sugars are moved from ground tissue into the phloem using Active transport

  -Waters moves from the xylem to the phloem using diffusion and is known as osmosis

  -This increases pressure in the phloem and pushes sugar away from the source towards the sugar sink
• Cuticle


  Waxy layer that helps prevent the loss of water
• Phloem 


  -Transports water and Nutrients

  -Moves materials in all directions

  -There are end walls between cells

  -Transports glucose from source to sink
• Xylem


  Forms one long tube through the plant
• Phototropism 


  the movement of a plant in response to light
• Gravitropism


  The movement of a plant in response to gravity
• Auxin


  -Tropism are controlled by a growth hormone in plants called auxin

  -Auxin moves in the stem in response to the position of the sun (phototropism) or position of the plant (gravitropism)

  -Auxin stimulates growth of cells, resulting in bending towards the light

  -In roots, auxin inhibits cell growth. This is why roots bend in opposite direction than stems
• Phototropism


  Stems have a positive reaction, roots have a negative reaction
• Gravitropism 


  Stems have a negative reaction, Roots have a positive reaction
• organelle responsible for photosynthesis

  Chloroplast
• Vascular tissue responsible for transporting sugars and other nutrients

  Phloem
• Organ system in the plant that exhibits positive phototropism 


  Shoot system
• A part of the plant that stores carbohydrates produced in the leaves

  Sugar Sink
• A waxy coating found on the epidermis of the plants to prevent water loss

  Cuticle
• Water molecules "sticking" to the side of the xylem assist in the movement of water up the stem of the plant


  Adhesion