Transcript 2 - Pleasantville High School

Energy Relationships
1. Photosynthesis: Chloroplast: energy from
the sun convert inorganic compounds to
organic compounds.
2. Respiration: mitochondria: convert
energy from organic compounds to form
compounds more easily used by the cell
(ATP)
Biochemical pathways: a series of reactions
in which the product of one reaction is
consumed in the next reaction.
ex. photosynthesis
Autotrophs
vs.
• Make own food from
organic compounds
• Examples: green plants
and algae
Heterotrophs
• Cannot make their own
organic compounds
• Examples: bacteria and
humans
***all life depends on the sun***
autotrophs use CO2 (carbon dioxide) and H2O (water) to make
glucose giving off O2
heterotrophs use C6H12O6 (glucose) and O2 (oxygen) giving off
CO2 and H2O
materials are constantly recycling
energy not recycled; must be supplied constantly
Photosynthesis Worksheet (read and answer)
Chloroplasts
Photosynthesis is a process in which sunlight energy is used to make glucose. The site of
photosynthesis is in the chloroplast – a organelle found in the leaves of green plants. The
main functions of chloroplasts are to produce food (glucose) during photosynthesis, and to
store food energy. Chloroplasts contain the pigment, chlorophyll. Chlorophyll absorbs most
of the colors in the color spectrum, and reflects only green and yellow wavelengths of light.
This is why we see leaves as green or yellow – because these colors are reflected into our
eyes.
1. What is photosynthesis?
2. Where does photosynthesis occur?
3. What are chloroplasts and where are they found?
4. What are the two main functions of chloroplasts?
5. Why doe most leaves appear green?
6. What is the primary pigment found in the chloroplast?
Photosynthesis
Glucose is another name for sugar. The molecular formula for glucose in C6H12O6. Plants
make sugar by using the energy from sunlight to transform CO2 from the air with water
from the ground into glucose. This process, called photosynthesis, occurs in the
chloroplast of the plant cell. During this process, oxygen (O2) is created as a waste
product and is released into the air for us to breath. The formula for photosynthesis is:
CO2 + H2O + sunlight ---- C6H12O6 + O2
This formula says that carbon dioxide and water molecules are combined with the
energy from sunlight to produce sugar and oxygen. The reactants in photosynthesis
(what is used) are CO2, water and sun. The plant gets water from the ground through its
roots. The plant collects carbon dioxide from the air. Much of the carbon dioxide comes
from living organisms that exhale it, but some also comes from factory smokestacks and
car fumes.
7. What is the formula for photosynthesis?
8. What three things are used to make glucose in photosynthesis?
9. Where does the water come from?
10. Where does the water enter the plant?
11. What are some sources of CO2?
12. What type of energy does the plant use to convert CO2 and
H2O into sugar?
The products (what is made) are glucose and oxygen. The glucose produced is used
by the plant for energy and growth. We also use this glucose by eating plants. The
oxygen produced is released into the air for us to breath. Photosynthesis is essential
for all life on earth, because it provides food and oxygen.
13. What is produced in photosynthesis?
14. What is the glucose used for?
15. What is the oxygen used for?
Photosynthesis
I. Capturing the Energy in Light
Photosynthesis summary equation:
6CO2
carbon dioxide
+
6H2O
water
+
light

C6H12O6
glucose
+
6O2
oxygen
•
•
•
•
•
•
II. Phases (controlled by enzymes)
1. Light Reactions
also called photolysis
Light absorption in grana of chloroplasts Light and
Pigments
chlorophyll trap energy from light (sun or artificial)
water molecules split (photolysis) and oxygen is
released from water; proved with oxygen-18
leftover energy produced stored in ATP
grana
Light and Pigments
light from sun appears clear/ opaque but is composed of many colors
least energy 
red
orange
yellow
visible spectrum
green
blue
blue
most energy  violet
blue/violet is most absorbed, and used most by the plant
green/yellow is most reflected, leased used
• chlorophyll a: directly involved in light reactions
• Accessory Pigments
• chlorophyll b: accessory pigment
carotenoids: orange
The Absorption of Chlorophyll
A pigment is a substance that absorbs and reflects light of particular wavelengths.
For example, the yellow-green color of a leaf is due to a pigment in the leaf called
chlorophyll. When white light (which contains all of the colors of the spectrum)
shines on chlorophyll, the chlorophyll absorbs most of the red, orange, blue, and
violet and reflects most of the green and yellow. That is why you see a yellow-green
color. Think of a pigment as a sponge that soaks up all of the other colors of the
spectrum except the one you see.
A spectrophotometer is an instrument that is used to measure the amount of light
absorbed by a pigment. Below is a graph showing the percentage of light energy
reflected for the absorption spectrum for chlorophyll. The highest peaks represent
colors that chlorophyll absorbs the most. Therefore, they are the least visible.
% of light absorbed
100
ABSORPTION SPECTRUM FOR CHLOROPHYLL
Chlorophyll a
50
.- ChtorophyH b
I
I
I
I.
\
\
.
0
3000
'
5000
4000
violet
blue
green
6000
yellow
orange
7000
red
Wavelength (in angstroms)
Use the above ·graph to answer the following questions.
I . Which of the colors absorbed by chlorophyll is least visible? ________________________________
2. What is its approximate wavelength? _________________________________
3. What percentage of light energy absorbed does this peak represent? _____________________
4. How much of this color is being reflected? ___________________________
5. What percentage of light energy absorbed by chlorophyll does the orange spectrum peak represent? _____________
6. Why would you say there are no peaks in the range between 5000 angstroms and 6100 angstroms? _________________________
7. Are you able to see the light in the yellow-green part of the spectrum? Explain why. ____________,
_______________________________________________________________________________________________
8. Arrange the colors in the absorption spectrum of chlorophyll in order of their visibility.
Place the most visible color first. ________________________________________________________________________________
PERCENT OF LIGHT ENERGY REFLECTED BY CHLOROPHYLL
Percent of light energy
reflected
100
90
_ _,
.)
80
r----
-
7060
50
40-
,.----
r---
30 20
10-
.11
violet
blue
green
yellow
orange
red
wavelength ( in angstroms)
Use the bar graph, which shows the percentage of light energy reflected by chlorophyll, to
answer the following questions. The graph was derived from the chlorophyll absorption
spectrum.
9. Which color in this spectrum is most visible? ------------- -----------------------10. What is the approximate percentage of light energy reflected for this color?------- ------11. What percentage.9f light energy absorbed does this represent? ---------------------------
12. If everything above 50 percent of light energy reflected is visible to the human eye, is red
light, part of the mixture of colors seen in light reflected by chlorophyll? ----- - ---- --
..
pigments easily separated by chromatography
The diagram below represents the results of a laboratory procedure.
This procedure is used to
(1) separate molecules in a liquid mixture
(2) detect glucose in a solution
(3) determine the rate of photosynthesis in plants
(4) examine the gene sequences of organisms
2. Dark Reactions
stroma
* also called carbon fixation
•take place in stroma of chloroplasts;
carbon dioxide is fixed in carbohydrate
•PGAL (phosphoglyceraldehyde; 3 carbon)
is formed
* glucose is synthesized from two 3-C PGAL
•molecules; called C-3 pathway
Alternative Pathways
**** C-4 pathway; fix CO2 in 4 carbon
compounds
ex. corn, millet, crabgrass
****CAM; take in carbon dioxide at night
and fix it into organic compounds
ex. cactus, pineapple in hot dry climates
Rate of Photosynthesis Affected
by:
*. amount of carbon dioxide
*. amount of water
*. amount of light
Cellular Respiration
making ATP by breaking down organic compounds
summary equation:
C6H12O6 +
6O2
glucose
oxygen
energy

6CO2
+
carbon dioxide
6H2O
water
+
Steps:
1.Glycolysis
2. ANAEROBIC Respiration (no oxygen)
OR AEROBIC Respiration (oxygen)
36 ATP
1. Glycolysis
occurs outside the MITOCHONDRIA(in the cytoplasm)
glucose + 2 ATP  2 PGAL  2 pyruvic acid + 4 ATP
Net gain: 2 ATP
2. Aerobic Respiration: if OXYGEN is available
occurs in the MITOCHONDRIA
2 pyruvic acid + oxygen  carbon dioxide + water + 34 ATP
Net gain of ATP during aerobic respiration = 34
Total ATP from both stages = 36
Base your answers to questions 1 and 2 on the word equations below and on your knowledge
of biology.
The equations represent two biochemical processes that occur in living organisms. The letter X
represents a molecule produced from process 1.
Process 1: oxygen + glucose → carbon dioxide + water + X
Process 2: carbon dioxide + water → oxygen + glucose
1. Identify the molecule represented by letter X in process 1.
__________________________________
2. Which process occurs in the cells of a green plant leaf?
(1) process 1, only
(2) neither process 1 nor process 2
(3) process 2, only
(4) both process 1 and process 2
2. ANAEROBIC RESPIRATION
Fermentation: no oxygen available
a. Lactic Acid Fermentation
occurs in MUSCLE cells
glucose  pyruvic acid  lactic acid + 2 ATP
muscle sore, cramps
b. Alcoholic Fermentation
some plant cells, yeast
glucose  pyruvic acid  ethyl alcohol + 2 ATP
WINE AND BREAD making
The laboratory setups represented below were used to investigate the effect of temperature on cellular respiration in yeast single-celled organism).
Each of two flasks containing equal amounts of a yeast-glucose solution was submerged in a water bath, one kept at 20°C and one kept at 35°C. The
number of gas bubbles released from the glass tube in each setup was observed and the results were recorded every 5 minutes for a period of 25
minutes. The data are summarized in the table below.
State one relationship between temperature
and the rate of gas production in yeast. [1]
Identity the gas that would be produced by the process taking
place in both laboratory setups. [1]
_________________________________
Photosynthesis Multiple Choice Questions
1. A green plant is kept in a brightly lighted area for 48 hours. What will most likely occur if the light intensity is
then reduced slightly during the next 48 hours?
1. Photosynthesis will stop completely.
2. The rate at which nitrogen is used by the plant will increase.
3. The rate at which oxygen is released from the plant will decrease.
4. Glucose production inside each plant cell will increase.
2. An inorganic molecule required by green plants for the process of photosynthesis is
1. oxygen
2. starch
3. carbon dioxide
4. Glucose
.
3. If the leaves of a geranium plant receive an adequate supply of raw materials, which graph below
shows how the rate of photosynthesis is related to increasing light intensity received by the plant?
1.
2.
3.
4. Which activity occurs in the process of photosynthesis?
1. Chemical energy from organic molecules is converted into light energy.
2. Organic molecules are obtained from the environment.
3. Organic molecules are converted into inorganic food molecules.
4. Light energy is converted into the chemical energy of organic molecules.
5. Photosynthesis is the process by which
1. the potential energy of simple sugars is transferred to ATP molecules
2. simple sugars are gradually broken down to form lactic acid or alcohol
3. two simple sugar molecules combine to form maltose and water
4. light energy is converted into the chemical energy of simple sugars
4.
4. decomposition
6.
8. Which biological process is the main source of atmospheric oxygen?
1. respiration
2. photosynthesis
3. hydrolysis
4. Synthesis
9.
The graph represents the absorption spectrum of chlorophyll. The graph indicates that the energy used in
photosynthesis is most likely obtained from which regions of the spectrum?
1. yellow and orange red
2. violet blue and green
3. orange red and violet blue
4. green and yellow
10. Eating a sweet potato provides energy for human metabolic processes. The original source of this energy is the energy
1. in protein molecules stored within the potato
2. from starch molecules absorbed by the potato plant
3. made available by photosynthesis
4. in vitamins and minerals found in the soil
11. The mass of some corn plants at the end of their growth period was 6 tons per acre. Most of this mass was produced from
1. water and organic compounds absorbed from the soil
2. minerals from the soil and oxygen from the air
3. minerals and organic materials absorbed from the soil
4. water from the soil and carbon dioxide from the air
12. The dense needles of Douglas fir trees can prevent most light from reaching the forest floor. This situation would have the most immediate effe
1. producers
2. carnivores
3. herbivores
4. decomposers
13.
The diagram represents part of a life process in a leaf chloroplast.
If the process illustrated in the diagram is interrupted by a chemical at point X, there would be an immediate effect on the release of
1.chlorophyll
2.nitrogen
3.carbon dioxide
4.oxygen
14. The equation below represents a summary of a biological process.
carbon dioxide + water → glucose + water + oxygen
This process is completed in
1. mitochondria
2. ribosomes
3. cell membranes
4. Chloroplasts
15. Which process is directly used by autotrophs to store energy in glucose?
1. diffusion
2. photosynthesis
3. respiration
4. active transport
16. Organisms that have the ability to use an atmospheric gas to produce an organic nutrient are known as
1. herbivores
2. decomposers
3. carnivores
4. autotrophs
17. Leaves of green plants contain openings known as stomates, which are opened and closed by specialized cells
allowing for gas exchange between the leaf and the outside environment. Which phrase best represents the net flow of
gases involved in photosynthesis into and out of the leaf through these openings on a sunny day?
1. carbon dioxide moves in; oxygen moves out
2. carbon dioxide and oxygen move in; ozone moves out
3. oxygen moves in; nitrogen moves out
4. water and ozone move in; carbon dioxide moves out
18. Which process usually uses carbon dioxide molecules?
1. cellular respiration
2. asexual reproduction
3. active transport
4. autotrophic nutrition
19. The graph below shows the results of an experiment in which a container of oxygen-using bacteria
and strands of a green alga were exposed to light of different colors.
Which statement best explains the results of this experiment?
1.
2.
3.
4.
The rate of photosynthesis is affected by variations in the light.
In all environments light is a vital resource.
The activities of bacteria and algae are not related.
Uneven numbers and types of species can upset ecosystem stability.
20.
Which process provides the initial energy to support all the levels in the energy pyramid shown below?
1.circulation
2.photosynthesis
3.active transport
4.Digestion
Constructed Response Questions
The Control of Transpiration
Plants normally lose water from openings (stomates) in their leaves. The water loss typically occurs
during daylight hours when plants are exposed to the Sun. This water loss, known as transpiration, is
both beneficial and harmful to plants. Scientists believe wind and high temperatures increase the rate of
transpiration, but the size of each stomate opening can be regulated. Reducing the size of the openings
during drought conditions may help reduce the dehydration and wilting that would otherwise occur. A
leaf may lose more than its own weight in water each day. Transpiration also lowers the internal
temperature of the leaf as water evaporates. On hot days, temperatures in the leaves may be from 3° to
15°C cooler than the outside air. With stomates open, vital gases may be exchanged between the leaf
tissues and the outside environment. Researchers have also found many plants that use another
response when leaf temperatures rise. Special molecules known as heat shock proteins are produced
by plant cells and help to hold enzymes in their functional shapes.
Identify the specific leaf structures that regulate the opening and closing of stomates.
Identify two of the "vital gases" that are exchanged between leaf tissues and the outside
environment.
State one way transpiration is beneficial to plants.
In some land plants, guard cells are found only on the lower surfaces of the leaves. In some water plants, guard cells are found only on
the upper surfaces of the leaves. Explain how guard cells in both land and water plants help maintain homeostasis. In your answer be
sure to:
• identify one function regulated by the guard cells in leaves
• explain how guard cells carry out this function
• give one possible evolutionary advantage of the position of the guard cells on the leaves of land plants
_______________________________________________________________________________________________________________
_______________________________________________________________________________________________________________
_______________________________________________________________________________________________________________
_______________________________________________________________________________________________________________
Base your answer to the following question on the investigation described below and on your knowledge of biology.
As part of an investigation, 10 bean seedlings in one setup were grown in the dark, while 10 seedlings in another setup
were grown in sunlight. All other growth conditions were kept the same in both setups. The seedlings grown in the dark were white
with long, slender stems. These seedlings soon died. The seedlings grown in the sunlight were green and healthy.
Identify the independent variable in this investigation
______________________________________________________
The diagram below shows the setup of an experiment.
A)Using one or more complete sentences, state a problem that could be investigated using this experimental setup.
_________________________________________________________________________________________________________________________