module 2 - biological elements and water Flashcards
what are the 4 key elements that make up all living things?
C (carbon)
H (hydrogen)
O (oxygen)
N (nitrogen)
what are the other 2 imporant elements involved in the composition of biologican world?
P (phosphorous)
S (sulpher)
what are the 5 cations that play an important role in the composition of biological world?
Ca2+
Na+
k+
H+
NH4+
what is the role of Ca2+?
nerve impulse transmission and muscle contraction
what is the role of Na2+?
nerve impulse transmission and kidney function
what is the role of K+?
nerve impulse transmission and stomatal opening
what is the role of H+?
catalysis of reactions
proton pump in photosynthesis
pH determination
what is the role of NH4+?
production of nitrate ions (NO3-)
what are the 5 anions that play an important role in the composition of biological world?
NO3-
HCO3-
Cl-
PO4*3-
OH-
what is the role of Nitrate ions (NO3-) ?
Nitrogen supply to plants for amino acid and protein formation
what is the role of Hydrogen carbonate ions (HCO3-) ?
Maintenance of blood pH
what is the role of Chloride ions (Cl-)?
Balance positive charge of sodium and potassium ions in cells
what is the role of Phosphate ions (PO43-)?
Cell membrane formation
nucleic acid and ATP formation and bone formation
what is the role of Hydroxide ions (OH-)?
Catalysis of reactions, pH determination
which elements are in a carbohydrates?
carbon, hydrogen and oxygen
what elements are present in lipids?
carbon, hydrogen and oxygen
Which elements are found in proteins?
Carbon, hydrogen, oxygen, nitrogen and sulphur.
Which elements are found in nucleic acids?
Carbon, hydrogen, oxygen, nitrogen and phosphorus
Define the term ‘polar’ in relation to molecules.
Molecules that have regions or negativity and regions of positivity
This is due to the way in which electrons are distributed between elements joined by a covalent bond.
Explain how polar molecules like water interact with each other
The positive and negative regions of the molecules attract each other and form hydrogen bonds.
These bonds give water its cohesive properties - it moves as one body because the molecules are attracted to each other.
These bonds also give water its adhesive properties - it molecules are attracted to other surfaces
properties of hydrogen bonds?
relativly weak interactions between R groups of different partial chages e.g O and H in different H2O molecules
What are the unique characteristics of water that are essential for life on Earth?
Unusually high specific heat capacity (boiling point).
Becomes less dense when it freezes.
Cohesive properties
Adhesive properties
‘Skin’ of surface tension
habitat
solvent
transport
temp control
Why is it good that water has a high specific heat capacity?
Keeps habitats stable for living things as a lot of energy is needed to change it by a degree.
Because ice is less dense than water what two things does this allow it to do?
create a stable environment for aquatic animals to live in throughout the winter
acts as an isulating layer for bodies of water against extreme cold
Because water is a good solvent it can do what two things?
Molecules and ions can move around and react together in water
Molecules and ions can be transported around living things while dissolved in water
what makes water a good transport medium?
cohesion between water molecules means that when water is transported theough the body, molecules will stick together
adhesion occurs between water and another polar molecule
the effects of both cohesion and adhesion = cappilary action
water can rise up narrow tubes against gravity
why is it good that water is stable?
because water isnt easily innfluenced by temp or evapourate easily it provides a constant environment
what does surface tension allow?
some insects such as pond skaters live on the surface of the water
surafe tension is strong enough to allow this to happen
what does it mean if water acts as a coolant?
Water acts as a coolant, helping to buffer temperature changes during chemical reactions in prokaryotic and eukaroytic cells because of the large amounts of energy required to overcome hydrogen bonding. Maintaining constant temperatures in cellular environments is important as enzymes are often only active in a narrow temperature range.
