2. Why are we studying water?
▪ All life occurs in water
◆ inside & outside the cell
3. AP Biology
How much water is there?
~75% planet and person is composed of water
4. Check this out!
4
1. Sketch a model of how a lizard “walks” on water. How does it work? Include
labels, arrows, anything that will help you describe your model. Be sure to include
the properties of water in your explanation.
2. Compare and discuss with your table partner. How/where do you agree?
Disagree? Continue to add to your model as needed.
3. With your lab group: compare models and discuss. Modify your model as needed.
5. Now check this out!5
Why can the snowmobile make it across the
pond while the human can’t?
11. Why is “ice floats”
important?
▪ Oceans & lakes don’t freeze solid
◆ if ice sank…
▪ eventually all ponds, lakes & even ocean would
freeze solid
▪ during summer, only upper few inches would
thaw
◆ surface ice insulates water below
▪ allowing life to survive the winter
12. Important Properties
of Water
The attraction of
two different
substances -
this is why water
sticks to things
like trees and
glass.
12
Adhesion
13. How is the capillary
action of the
school’s paper
towels?
Part of how
trees move
water from
roots to
leaves!
13
14. Important Properties
of Water
The attraction
between particles
of the same
substance - this
is why water
sticks to water!
**CAUSES
SURFACE
TENSION**
Can you suck
water up through
a straw? Can you
suck sugar up
through a straw!
14
Cohesion
15. 15
Hey kids, water here,
nice to meet ya! What’s
an example of cohesion?
Now what’s an
example of
adhesion?
16. Important Properties
of Water
Water can
dissolve almost
anything, it can
dissolve more
substances than
any other liquid!
16
Universal
Solvent
17. 17
The substance that gets
dissolved.
The substance that does
the dissolving.
The solute
and solvent
combined.
19. Important Properties
of Water Specific Heat →
the amount of
heat needed to
raise or lower the
temp of 1g of a
substance by one
degree celsius
19
High
Specific
Heat
20. Important Properties
of Water
Heat of
Vaporization →
the amount of
energy needed to
convert 1g of a
substance from a
liquid to a gas
20
High Heat
of
Vaporizatio
n
21. Water and the pH scale -
water breaks apart into
ions (charged particles)
▪ Hydrogen ion (H+) splits off from water to leave a
hydroxide ion (-OH)
H2O → H+ + -OH
▪ If concentration of 2 ions is equal, water is neutral
▪ If [H+] > [-OH], water is acidic
▪ If [-OH] > [H+], water is basic
▪ pH scale = how acidic or basic a solution is
22. pH Scale
▪ In neutral solution pH
= 7
▪ Acids (like vinegar)
◆ 1-6
▪ Bases (like bleach)
◆ 8-14
▪ Most body fluids have
a pH between 6-8
(stomach acid = 2)
23. ”
We know that water is necessary for
life, but can also kill you...how does
THAT happen?
23
24. AP Biology
We can go 3 WEEKS or more
without food, but only 3-4
DAYS without water
You should drink
about 8- 8oz glasses
of water per day (half
gallon).
How much do you
drink?
26. How far do you have to
walk to fill your water
bottle? How much does
that bottle weigh?
Water and YOU - how fortunate you are.
Africa - 40lb. bucket of water
carried an ave. of 3.7 miles
EVERY DAY!
27. ▪ Water is a polar molecule
▪ The special properties of water make life
on Earth possible
▪ The chemical behavior of water governs
how organisms function
Importance of Water
So now can you explain
the lizard, human, and
snowmobile?
28. What do you think?
▹ Why can the basilisk lizards run on
water but humans can’t?
▹ Why can the snowmobile go
across the pond without sinking?
▹ What makes water hold up a lizard
and snowmobile but not a person?
28
