Water A1.1 Flashcards
What makes water so useful for life?
- makes up cytoplasm (which is responsible for metabolic reactions)
- good solvent (which is able to transport things in and out of blood as plasma)
What is the chemical make-up of a water molecule?
It is a polar covalent bond that has an unequal sharing of electrons (which makes the hydrogen partially positive and the oxygen partially negative)
Cohesion
caused by hydrogen bonds (these hydrogen bonds are weak on their own but stronger together, intermolecular forces not actual bonds) making the water molecules to stick to one another.
Surface tension
caused by cohesion of water molecules and are able to withstand the weight of very light insects. Water molecules do not bond to the oxygen molecules above the surface making the bond below stronger.
- making habitats for insects
- droplets form
How does cohesion apply to biology?
the transport of water up xylem in plants despite the tension from the roots pulling the water downwards (as well as gravity)
energy is needed to break through the surface tension of water (due to the hydrogen bonds needing to be broken simultaneously) so it makes habitats for organisms like water striders and mosquitos.
Adhesion
caused by the polarity of water being attracted to other polar/charged surfaces.
How does adhesion apply to biology?
water is drawn up xylem vessels to keep plants moist.
also works with cohesion in xylems to work against gravity pulling it down.
plant cells exposed to air is continuously moist.
Meniscus
is the curve in a tube seen when water is adhering to a polar surface. Non-polar surfaces do not have meniscus.
Capillary action
water is drawn upwards through narrow tubes.
Water as solvent
polar solutes dissolve in polar solvents.
makes metabolism and transport possible.
How does water make metabolism and transport possible?
because cytoplasm is made of dissolved substances and the water is the solvent (aqueous solution) solutes can move around and interact .
the dissolved enzymes catalyze chemical reactions known as metabolism.
water makes the components of the reaction come together on active sites.
Aqueous solution
water is the solvent of solutes. this makes the solutes able to move around and interact.
Hydrophilic
water-loving
polar/charged molecule and soluble
Hydrophobic
water-hating
non-polar/neutral charged molecule and repel water/not soluble, dissolve in non-polar solvents
Water’s solvent properties help with transport in plants via:
mineral ions in xylem sap
sucrose and products of photosynthesis in phloem sap.
Glucose being transported in blood
polar/hydrophilic/soluble
carried in blood plasma.
Amino acids being transported in blood
all amino acids are soluble enough to be carried in blood plasma
Oxygen, nitrogen, carbon, and other gases being transported in blood
nonpolar/hydrophobic
oxygen can dissolve in blood but not enough to provide aerobic cell respiration.
this is why hemoglobin exist in red blood cells, they have binding sites for oxygen and greatly increase the capacity of blood to transport oxygen.
Fats + fatty acids being transported in blood
nonpolar/insoluble
carried in blood through lipoprotein complexes that pack the fatty acids and ships them so that fat doesn’t turn into bulky droplets. there is a single layer of phospholipid on outside and fat inside.
Steroid hormones being transported in blood
nonpolar/hydrophobic
responsible for transport in blood when bound to proteins.
Cholesterol being transported in blood
nonpolar/low solubility
transported around circulatory system via lipoproteins.
Buoyancy
the vertical force of the liquid or gas on an object placed on it.
force = weight of object, it floats
density of object < liquid, it floats
force > gravity on object, it floats
How does buoyancy apply to biology?
bony fish have air-filled swim bladder to control overall density
cyanobateria has gas vesicles to adjust how close to surface they float.
Viscosity
the resistance of a fluid to flow.
the resistance is due to internal friction which is caused when one part of a liquid moves relative to another.
- the solutes cause viscosity to become higher
high viscosity = more friction = more resistance to flow