1. Plants Part 2

2. Photosynthesis and Respiration
Taking in Raw Materials
1. food, oxygen produced
2. Movement of Materials
a. Take in sunlight, water, carbon dioxide. Give off oxygen.
b. Leaves are where
gas exchange occurs.

3. Leaf Structure and Function
a. cuticle
waxy outer covering
b. epidermis
top layer of the leaf
c. stomata
openings in the leaf ;water is lost through stomata
d. guard cells
cells on either side of the stomata that cause them to open and close
e. water enters through roots
f. palisade layer
just underneath the epidermis.
Food is made here.
g. spongy layer
below the palisade layer

4. Chloroplasts and Plant Pigments
a. chloroplasts
take in sunlight
b. chlorophyll
green pigment inside the chloroplast
c. green color of the tree leaves is due to green light energy being reflected from chlorophyll
d. In the fall, chlorophyll in the
leaves breaks down and leaves
change color as the other pigments
become visible.

5. Food-Making Process Photosynthesis Light-Dependent Reactions
process in which plant chlorophyll traps light energy and uses the energy from light to make sugars (food).
produces nearly all the food for all other forms of life on Earth
Light-Dependent Reactions
require light
chlorophyll traps sunlight during light- dependent and uses it to make food.

6. Light-Independent Reactions Importance of Photosynthesis
does not require light
Importance of Photosynthesis
produces food/glucose/C 6 H 12 O 6
releases oxygen / O2
As much as 90% of our oxygen comes from photosynthesis.

7. The Breakdown of Food
Respiration – series of chemical reactions that breaks down food molecules and releases energy.
changes energy into a food form that all cells can use
Aerobic respiration – occurs in the mitochondria of plants and animals with one or more cells and a nucleus (uses oxygen)

8. Aerobic Respiration Reactants (start with)= Products (results) =
Glucose - C 6 H 12 O 6
Oxygen- O2 are taken in.
Products (results) =
Carbon dioxide(CO2),
Water vapor(H2O), and
Energy (ATP) are released.
Importance of Respiration
a. changes food energy into a form the cells can use
b. returns carbon dioxide to the atmosphere.

9. Comparison of Photosynthesis and Respiration
Almost reverse equations of each other
Photosynthesis occurs only in cells with chloroplasts. (Producers ex. Plants)
Any cell with mitochondria can undergo respiration (plants and animals)

10. Plant Responses What are plant responses? Response Stimuli (stimulus)
involves movement either toward or away from the stimulus.
 Stimuli (stimulus)
external
comes from outside the organism
internal
comes from inside the organism
All living things respond to stimuli.

12. Tropism
movement caused by a change in growth; can be positive or negative.
Light
When plants respond to light, causes a plant to grow toward the source of light. Positive
Gravity
Downward growth of roots – positive. Upward growth of stem – negative.

13. Plant Hormones
Plant Hormones control the changes in growth of a plant. Examples: (ethylene /auxins / gibberellins / cytokinins )
Ethylene
stimulates the ripening process
Auxin
controls plant growth toward the light
Synthetic (man-made) auxins are used as fertilizers; also used as weed killers in high doses
Gibberellins
mixed with water and sprayed on plants to stimulate plant stems to grow and seeds to germinate (fertilizers)
Cytokinins sprayed on stored vegetables to keep them fresh longer

14. Photoperiodism
plant’s response to the number of hours of daylight and darkness.
Long-day plants – require less than hours of darkness to flower.
spinach, lettuce, beets
Short-day plants – need 12 or more hours of darkness to flower
strawberries, ragweed
Day-neutral plants – may have a range
of hours of darkness
dandelions, roses