Chapter 1: Inorganic Ions/Water

Question 1

What is a cation?

Answer 1

an ion with a positive charge

Question 2

What is an anion?

Answer 2

an ion with a negative charge

Question 3

What is the role of the calcium ion in the body?

Answer 3

• involved in the TRANSMISSION of nerve impulses
• the release of insulin from the pancreas
• acts as a cofactor for many enzymes (e.g in blood clotting)
• important for bone formation

Question 4

What is the role of sodium ions in the body?

Answer 4

• important for GENERATING nerve impulses
• muscle contraction
• regulating fluid balance in the body

Question 5

What is the role of potassium ions organisms?

Answer 5

• important for generating nerve impulses for muscle contraction
• regulating fluid balance in the body
• activates essential enzymes needed for photosynthesis in plant cells

Question 6

What is the role of hydrogen ions in organisms?

Answer 6

• affects the pH of substances (more H, more acidic)

- important for photosynthesis reactions- that occur in the thylakoid membrane (inside chloroplasts)

Question 7

What is the role of ammonium ions and nitrate ions in organisms?

Answer 7

• absorbed from the soil by plants

- important source of nitrogen (then used to make amino acids and nucleic acids)

Question 8

What is the role of hydrogencarbonate ions in organisms?

Answer 8

• acts as a buffer

- helps to maintain the pH of blood

Question 9

What is the role of chloride ions in organisms?

Answer 9

• involved in the chloride shift (helps maintain the pH of blood during gas exchange)
• acts as a cofactor for amylase
• involved in some nerve impulses

Question 10

What is the role of phosphate ions in organisms?

Answer 10

• involved in photosynthesis and respiration rxns.
• needed for the synthesis of many biological molecules
  (e. g-nucleotides, phospholipids and calcium phosphate which strengthens bones)

Question 11

What is the use of hydroxide ions in organisms?

Answer 11

affects pH

more OH- ions than H+ ions in a solution creates an alkali

Question 12

What type of molecule is water?

Answer 12

-dipolar
O atom has slight -ve charge
H atom has slight +ve charge

Question 13

What are the IMF between water molecules?

Answer 13

hydrogen bonding between the +ve H and the lone pairs on O atom (attraction between oppositely charged poles), this causes water mol. to stick together

Question 14

What is the S.H.C of water (relative) and why?

Answer 14

very high

because water mol stick together, so it takes more energy to separate molecules

Question 15

Why is it beneficial for water to have a high S.H.C?

Answer 15

it acts as a buffer against sudden temperature variations
making an aquatic environment stable
also, buffers internal temp. in mammals from changing too much-good temp. for enzyme function

Question 16

What are the properties of water? (5)

Answer 16

• important metabolite
• high S.H.C (buffer for temp)
• important solvent (dipolar nature)
• large latent heat of vaporisation (cooling effect)
• strong cohesion between water mol (due to Hydrogen bonding)

Question 17

Why is a high latent heat of water useful?

Answer 17

evaporation of water from an animal (sweat) transfers a lot of energy to the surroundings, so it is effective for cooling as the body heat is used to evaporate water

Question 18

Why is water cohesive and why is it useful?

Answer 18

• tendency of mol. to stick together due to hydrogen bonding
• allows water to be pulled through columns (xylem)
• creates surface tension, can support small animals such as pond skaters

Question 19

What is the importance of water for living organisms? (5)

Answer 19

• metabolite
• solvency
• cooling
• provides support to cells
• transparent

Question 20

How is water used as a metabolite?

Answer 20

• used for hydrolysis reactions (to break down many complex mol.)
• chemical reactions take place in aqueous solutions
• water is a major raw material in photosynthesis

Question 21

How is water used as a solvent?

Answer 21

water readily dissolves other substances:

• gases such as CO2 and O2
• wastes such as ammonia and urea
• dissolves inorganic ions and small hydrophilic mol (amino acids, ATP, monosaccharides)
• dissolves enzymes

Question 22

How can water provide support?

Answer 22

not easily compressed so provides support to cells

e.g- hydrostatic skeleton of earthworms, turgor pressure in herbaceous plants

Question 23

How is it useful that water is transparent?

Answer 23

aquatic plants can photosynthesise

aquatic animals can see because light rays can penetrate jelly-like fluid in eye and hit retina