Do Now 101
1. Plant and animal cells are different. Which organelle belongs to a
plant cell, animal cell or both (mitochondria, chloroplast, cell wall,
cell membrane).
2. What is the function of a:
 Chloroplast –
 Mitochondria –
Photosynthesis
&
Cellular Respiration
How do organisms obtain nutrients?
There are 2 ways:
1. Heterotrophs
• Unable to synthesize own food.
• Ingests food (nutrients) produced by, or available in, other
organisms.
2. Autotrophs
• Autotrophs make their own food. Also called producers
• Plants do not need to ingest food. Glucose (nutrient)
synthesized during photosynthesis
Why do living things need nutrition?
1. For energy to carry out Life Functions
What do you call the sum total of all the chemical reactions (life
functions) in an organism?
Metabolism
What are some types of autotrophs?
Mostly green plants and some single-celled organisms
– Trees, grass, bushes, photosynthetic bacteria, algae
Photosynthesis
How do autotrophs make food?
Photosynthesis
Photo I Synthesis
Light I Creates
Purpose of Photosynthesis:
 … Is to create or synthesize GLUCOSE for the plant. The plant then
uses the glucose to make ENERGY.
 Some animals eat plants so they can steal the glucose made in order
for them to make energy!
Put into words, this equation tells us….
• In the presence of light, plants transform CO2 and H2O into
Glucose (stored chemical food energy) and releases O2 as a
product.
http://www.teachersdomain.org/asset/tdc02_vid_photosynth/
Photosynthesis Equations
Carbon dioxide + water + light
C02 + H2O + Light
Inorganic molecules
Sun’s Energy
glucose+ oxygen
C6H12O6 + O2
Organic molecule + O2
Stored chemical energy (bonds)
1. How many types of enzymes will help catalyze the photosynthesis
reaction?
2. Could Photosynthesis occur without sunlight?
Hmmm…
1. What is the ultimate source of energy?
2. If photosynthesis did not take place, would we have oxygen
to breath?
Where does photosynthesis take place?
In chloroplasts found inside the cells of leaves
– Does photosynthesis take place in leaf, stems or a tree trunk?
How is light energy captured and used?
 Plant cells that are green contain chloroplasts.
 Chloroplasts contain chlorophyll….
1. What is chlorophyll?
 A pigment (type of protein) that reflects
green light and absorbs other colors.
 This is how light energy is captured!
2. Why are plants/leaves green?
 Green light is reflected by chlorophyll.
3. What colors are absorbed best?
 Blues / Violet & Red / Maroon
Does the color of light affect photosynthesis?
Conclusion: The color of light affects the rate of photosynthesis!
The Effect of the Color of Light on Plant Height
Fri
Sat
Sun
Mon
Tues
Wed
Thurs
Green
0
-
-
4 mm
9 mm
17 mm
20 mm
Blue
6 mm
-
-
43 mm
50 mm
67 mm
67 mm**
Red
2 mm
-
-
59 mm
64 mm
84 mm
87 mm
Yellow
-
-
-
-
-
-
-
Clear
0
-
-
37 mm
49 mm
70 mm
75 mm
No light filter
-
-
-
-
54 mm
66 mm
75 mm
http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS12/LS12.html
What is going on here?
The “thing” in the beaker is a green elodea plant. What are those
little bubbles in the test tube? Explain
Bubbles of oxygen produced
by Photosynthesis
Hmmm… How can we measure
the rate of photosynthesis?
Measure the amount of product produced!
– How?
1. Measure the amount of Oxygen produced (#of bubbles)
2. Measure the amount of plant (size, weight)
What could speed-up or slow-down
the rate of photosynthesis?
6C02 + 6H2O + Light
C6H12O6 + 6O2
http://www.biologycorner.com/flash/waterweed.html
Conclusions:
Color of light :
Light intensity:
Amount of CO2:
1. Predict what would happen if photosynthesis did not take
place? (give two examples).
2. How could you improve the rate of photosynthesis? (Give at
least 2 ways)
3. How could you slow down or even stop photosynthesis? (Give
at least 2 ways)
As the depth of the ocean increases, the amount of light that
penetrates to that depth decreases. At about 200 meters, little, if any,
light is present. The graph below illustrates the population size of four
different species at different water depths.
Which species most likely
performs
photosynthesis?
a.
b.
c.
d.
Why?
How do plants get materials needed for photosynthesis?
Roots -  Absorb water from the
ground.
Where does the water go once it is absorbed?
To the Leaves !
 Site of photosynthesis
 Where CO2 & Sunlight are absorbed (reactants)
 Where H2O and O2 leave the plant (waste products)
How does water get up to the leaves?
Transpiration pull
• Water evaporates through tiny holes in leaves called
stomata
• Water is drawn up from the roots and stems to replace
the lost water.
**Remember, water is cohesive… water molecules love to
stick together. When one water molecule evaporates, all
the water in the stem is pulled up!
https://www.youtube.com/watch?v=At1BJJDcXhk
Parts of leaf
1. Guard cells & stomata
2. Cuticle
3. Spongy & Palisade Mesophyll
Guard Cells & Stomata
Stomata – tiny opening on bottom-side of leaf. Where
water evaporates and where CO2 and O2 enter and leave
the cell. (H2O leaves through stoma)
Guard cells – two cells surrounding the stomata (opening).
These special cells open and close the stomata.
How do to the guard cells open and close?
When plant have lots of water, the cells become
expanded and “bow-out.” This opens the stomata.
When water is low, the cells deflate, and close.
***How do guard cells help
maintain homeostasis?
Palisade and Spongy Mesophyll
Palisade mesophyll
• Top of leaf
• Right beneath epidermis
• Absorbs most of the light
• Where most photosynthesis
happens in the leaf
Spongy mesophyll
• Beneath the palisade mesophyll (bottom of leaf)
• Loose tissue, with many air spaces
• Lots of CO2 and O2 found here
• Where gas exchange happens
Time out…
Answer Me 
1. How does CO2 and O2 enter and leave the cell?
2. How does water enter and leave the cell?
3. How is sunlight captured in leaves?
4. What process takes place in leaves? And what’s the purpose?
5. How do guard cells help maintain homeostasis?
Parts of leaf
1. Cuticle
Label your leaf! Page 6 in packet.
2. Guard cells & stomata
3. Spongy & Palisade Mesophyll
Another Look
Review
Review
Review
Do Now
1. Do plant cells have mitochondria?
2. Do plant cells use oxygen and glucose? Why?
3. So… do plants give off some carbon dioxide? (CO2)
Do Now
1. What is needed (reactants) for photosynthesis?
2. What are the products of photosynthesis?
3. Why does photosynthesis take place? Why is it important?
Do Now (5)
1. Finish the formula:
______________ + ________ + light
__________+ __________