unit 1: unity and diversity

• what are the physical and chemical properties of water that make it essential for life?

  -surface tension, the ability to resist an external force which helps in cohesion in the xylem to provide nutrients to the leave's of plants

  -cooling mechanisms, like sweating

  -heat exchange, like the ocean absorbing heat and releasing it slowly

  -heat distribution to help with regulating internal temperature
• what are the challenges of water as a habitat?

  challenges:

  • oxygen availability, if there is little oxygen in an aquatic environment can affect the organisms
  • temperature regulation, extreme temperature can stress aquatic organism

  solutions:

  • organisms use specialized respiratory system
  • organisms regulate their internal temperature
• what is an aquatic environment?

  habitat for water dependent living species
• what is water needed for?

  for metabolic reaction, water being the solvent and is involved in many chemical reactions like condensation and hydrolysis
• define hydrolysis

  a process of breaking down a chemical compound that involves splitting a bond and adding the elements of water
• hydrolysis reaction

  
• condensation reaction

  
• why is there hydrogen bonding?

  due to the polarity between two water molecules
• explain why hydrogen bonds are made?

  because of the unequal sharing of electrons, to be able to form bonds with other water molecules to create a chained bond and the bonds are key to many of the water's properties
• state the first cells originated in water

  the first cells are believed to have originated in water
• what are the opportunities of water as habitat?

  • buffering temperature, water's specific heat capacity creates a stable condition that can support ecosystems
  • nutrient availability, water bodies has many sources of water nutrients, including dissolved material waste
• explain the sharing of atoms in a polar covalent bond

  unequal sharing of electrons between two atoms
• explain the charges of hydrogen and oxygen

  • oxygen - attracts the shared electrons more strongly due to the high electronegativity (positive)
  • hydrogen - pulled away due to oxygen (negative)
• outline the consequences of the collective strength of hydrogen bonds between water molecules

  • high melting/boiling point - the hydrogen bonds between water molecules require a large amount of energy need to break
  • high specific heat capacity - a large amount of heat energy is needed to increase the temperature of water due to the hydrogen bonding
  • high heat of vaporization - hydrogen bonds require significant energy to break during the phase of liquid to gas
• define cohesion

  when water molecules stick to each other using hydrogen bonds
• what does cohesion do?

  • allows plants to move water under tension in the xylem
  • contributes to surface tension which is important to living organism
• why is surface tension important for organism?

  ability to have a habitat near water, which has many nutrients for organisms and provides a stable a environment
• define surface tension

  ability to resist an external force
• outline the cause of surface tension

  water molecules being more attracted to each other more than the air so the force is pulled inwards
• what is the xylem's structure?

  long thin and narrow vascular plants that form a continuous tube from the roots to the leaves
• cohesion in the xylem

  • pulls up water molecules in a chain and out of stomata with the help of hydrogen bonds which help keep it in a continuous column
  • contributes to the surface tension
  • go upwards, despite of the tension caused by transpiration
• hydrogen bonds = intermolecular forces
• define adhesion

  when water molecules stick to other charged/polar substances
• what is hydrophilic?

  charged substances that mix and dissolve in water
• where does hydrophilic reaction take place?

  in the phloem because of the cytoplasm and since it's a living cell
• what does adhesion do?

  • allows plants to move water using the capillary action
  • permits water to move through soil, against gravity
• how is glucose transported in the body?

  1. hydrogen bonds are formed with glucose
  2. allowing glucose to be transported around the body in the blood
• • glucose is a polar molecule
  • -OH
• cellulose

  • made up of glucose
  • water forms hydrogen bonds
  • cellulose is porous
  • allows structures with lots of cellulose to be able to absorb water, water sticks to the wall via hydrogen bonds
• apoplastic pathway

  • through cell wall
  • protects
  • outside
  • keeps it upright
• sympoplastic pathway

  • through cytoplasm
  • tension
  • inside
  • feeds
• define the capillary action

  movement of water through a narrow space, often in the opposite direction of the external forces like gravity
• what is the cause of the capillary action?

  • cohesion
  • adhesion
  • surface tension
• describe the capillary action in plant tissue

  1. water is absorbed by the roots
  2. water goes to the xylem
  3. capillary actions happens with the help of cohesion and adhesion
• soil is porous and polar which allows hydrogen bonds to be created
• effects of the capillary action

  • water availability to plants
  • helps distribute water, by allowing rainfall to spread horizontally and vertically
  • helps retain moisture by drawing water from the deeper layers towards the surface preventing it from being dry
• water is a medium for metabolism and a transport for plants and animals
• water is a solvent
• water has high specific heat capacity so it can absorb large amounts of energy without changing temperature
• what happens to solute when it dissolves in water?

  their molecules separate from each other and they become surrounded by water molecules which allows hydrogen bonds to be formed, which then allows for the solute to be dissolved