Author: Biology Junction Team

Photosynthesis Worksheet Ch6 BI

 

Photosynthesis

 

Section 6-1 Capturing Light Energy

1. All organisms require ___________________ to carry out their life functions.

2. ___________________ is the ultimate energy for all life on earth.

3. During photosynthesis, the energy from the sun is stored within _____________________

compounds, mainly the sugar _______________________.

4. What organisms can carry on photosynthesis?

5. Name several autotrophic organisms.

6. What is a biochemical pathway and give an example?

7. What gas is used by autotrophs & what gas is produced?

8. What organisms release stored energy from organic compounds through cellular respiration?

9. Draw the diagram showing energy storage & transfer between autotrophs & heterotrophs. (Figure 6.1)

10. What are the light reactions of plants and in what organelle do they occur?

11. Draw & label the parts of a chloroplast. Tell the function of each labeled part.

12. Flattened sacs in chloroplasts are known as ____________________ and are

_______________________ to each other.

13. Thylakoid sacs in chloroplasts are called _____________________________.

14. What gel-like solution surrounds the thylakoids inside the chloroplast?

15. What is the visible spectrum?

16. Name the 7 colors that make up the visible spectrum.

17. What 3 things can happen to light that strikes an object?

18. What are pigments & what is their function in plants?

19. Is red light reflected or absorbed by an object if the object appears red to your eyes?

20. Name the most important chloroplast pigment & tell the 2 most important types of this pigment.

21. Only ________________________ is directly in capturing light energy.

22. Chlorophyll b is an example of an ______________________ pigment in plants.

23.Name another accessory pigment & tell what colors it includes. When could you see these colors?

24. Chlorophyll is most abundant in the _____________________ of a plant, while accessory
pigments appear more in the _________________________ and fruits.

25. The _________________________ and ________________________ pigments are grouped
into clusters in the thylakoid membrane.

26. What is a photosystem?

27. Name the 2 types of photosystems.

28. The light reactions start when __________________ pigments absorb ______________.

29. Absorbed light is passed to a pair of ________________________ pigment molecules in
photosystem ________.

30. When light energy is absorbed by chlorophyll a molecules, what happens to its electrons?

31. Once these electrons become “excited”, they have enough energy to do what?

32. What are the chemicals called that pick up these freed electrons & where are they located?

33. These electrons lose _________________ as they are passed through a series of molecules
called the ______________________________________ chain.

34. Photosystem I chlorophyll molecules also absorb ________________, and its electrons
eventually combine with ______________________ to form NADPH.

35. What would happen if the electrons lost from photosystem II weren’t replaced?

36. ________________________ provides the replacement electrons for photosystem II when
water is __________________________.

37. Write the equation for the splitting of a water molecule.

38. What important gas is released when water is split?

39. ______________ or energy for a cell is synthesized during the light reactions in a process
called ________________________________.

Section 6-2 Calvin Cycle

40. The _________________ cycle is the second set of photosynthetic reactions that uses energy
stored in ________________ and _____________________ to make __________________
compounds.

41. Carbon atoms from ______________ are “fixed” into organic compounds in the Calvin
cycle in a process called carbon _________________________.

42. In what part of the chloroplast does the Calvin cycle occur?

43. Carbon dioxide combines with _______________ to make two molecules of
_____________________________.

44. PGA is converted into ________________, ADP, _________________, and
phosphate.

45. Carbohydrates made from PGAL in the Calvin cycle include the monosaccharides
______________________ and ______________________, the disaccharide
_______________________, and polysaccharides such as _____________________,
________________________, and _______________________.

46. Write the balanced equation for photosynthesis. (See bottom of page 118.)

47. Plants that fix carbon through the Calvin cycle are called what type of plants?

48. What are stomata & where are they located?

49. When would plant cells need to close or partially close their stomata?

50. Name 2 alternate carbon-fixing pathways used by plants in hot climates.

51. Plants that close their stomata during the hottest part of the day thus fixing carbon into four
carbon compounds are called ______________________. Name three.

52. CAM plants open stomata at ______________ and close during the _________________.

53. Name 3 environmental factors that affect the rate of photosynthesis.

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Photosynthesis Study Guide BI

 

 

Photosynthesis Study Guide

 

Give several examples of life processes that require energy.
What is the major light absorbing pigment in plants?
What two things are formed by plants when carbon dioxide & water are combined using sunlight as the energy?
Clusters of light absorbing pigments located in the thylakoid membranes of a chloroplast are called what?
Do all organisms require energy?
Are all wavelengths of sunlight absorbed by a plant to make sugar? Explain. 
Only ___________, not heterotrophs, carry on photosynthesis.
When the products of one chemical reaction are used as the reactants for the next reaction, the series of reactions is known as a ___________________ pathway.
Plants cells use light to make what two energy carrying molecules?
What sugar is the final product of photosynthesis?
Electrons are transported from one molecule to another by __________ atoms.
Can the dark reactions of photosynthesis occur during the daytime or only in the dark?
C4 and CAM plants use less water to make sugar than __________ plants.
How do heterotrophs obtain their energy?
What is the original source of energy for all living things on earth?
Stacks of thylakoids called grana are suspended in the fluid inside chloroplasts called __________.
Light travels to plants as tiny packets of radiant energy called _________.
Chlorophyll of plants looks green because green light is ______________ to your eye.
What happens to the electrons of chlorophyll when they are stuck by sunlight?
What gas is put back into our atmosphere by photosynthesis?
Complex carbohydrates are made during what cycle during photosynthesis?
What pigments give flower petals their colors?
Electrons raised to a higher energy level when struck by light enter what chain?
What important energy carrier molecule in photosynthesis picks up hydrogen atoms?
Oxygen made during photosynthesis comes from the splitting of what molecule?
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Photosynthesis

Photosynthesis
All Materials © Cmassengale

I. Capturing the Energy of Life

  1. All organisms require energy
  2. Some organisms (autotrophs) obtain energy directly from the sun and store it in organic compounds (glucose) during a process called photosynthesis

6CO2 + 6H2O + energy –>  6O2 + C6H12O6

II. Energy for Life Processes

  1. Energy is the ability to do work
  2. Work for a cell includes growth & repair, active transport across cell membranes, reproduction, synthesis of cellular products, etc.
  3. Work is the ability to change or move matter against other forces (W = F x D)
  4. Autotrophs or producers convert sunlight, CO2, and H2O into glucose (their food)
  5. Plants, algae, and blue-green bacteria, some prokaryotes, are producers or autotrophs
  6. Only 10% of the Earth’s 40 million species are autotrophs
  7. Other autotrophs use inorganic compounds instead of sunlight to make food; process known as chemosynthesis
  8. Producers make food for themselves and heterotrophs or consumers that cannot make food for themselves
  9. Heterotrophs include animals, fungi, & some bacteria, & protists

III.      Biochemical Pathways

  1. Photosynthesis and cellular respiration are biochemical pathways
  2. Biochemical pathways are a series of reactions where the product of one reaction is the reactant of the next
  3. Only autotrophs are capable of photosynthesis
  4. Both autotrophs & heterotrophs perform cellular respiration to release energy to do work
  5. In photosynthesis, CO2(carbon dioxide) and H2O (water) are combined to form C6H12O6 (glucose) & O2 (oxygen)
    6CO2 + 6H2O + energy –>  6O2 + C6H12O6
  6. In cellular respiration, O2 (oxygen) is used to burn C6H12O6 (glucose) & release CO2(carbon dioxide), H2O (water), and energy 
  7. Usable energy released in cellular respiration is called adenosine triphosphate or ATP

 

IV. Light Absorption in Chloroplasts

  1. Chloroplasts in plant & algal cells absorb light energy from the sun during the light dependent reactions
  2. Photosynthetic cells may have thousands of chloroplasts
  3. Chloroplasts are double membrane organelles with the an inner membrane folded into disc-shaped sacs called thylakoids
  4. Thylakoids, containing chlorophyll and other accessory pigments, are in stacks called granum (grana, plural)
  5. Grana are connected to each other & surrounded by a gel-like material called stroma
  6. Light-capturing pigments in the grana are organized into photosystems

 V. Pigments

  1. Light travels as waves & packets called photons
  2. Wavelength of light is the distance between 2 consecutive peaks or troughs

  1. Sunlight or white light is made of different wavelengths or colors carrying different amounts of energy
  2. A prism separates white light into 7 colors (red, orange, yellow, green, blue, indigo, & violet) ROY G. BIV
  3. These colors are called the visible spectrum

  1. When light strikes an object, it is absorbed, transmitted, or reflected
  2. When all colors are absorbed, the object appears black
  3. When all colors are reflected, the object appears white
  4. If only one color is reflected (green), the object appears that color (e.g. Chlorophyll)
VI. Pigments in the Chloroplasts

 

 chlorophyll is found only in the chloroplasts
  1. Thylakoids contain a variety of pigments ( green red, orange, yellow…)
  2. Chlorophyll  (C55H70MgN4O6) is the most common pigment in plants & algae
  3. Chlorophyll a & chlorophyll b are the 2 most common types of chlorophyll in autotrophs
  4. Chlorophyll absorbs only red, blue, & violet light
  5. Chlorophyll b absorbs colors or light energy NOT absorbed by chlorophyll a
  6. The light energy absorbed by chlorophyll b is transferred to chlorophyll a in the light reactions

structural formula of chlorophyll

  1. Carotenoids are accessory pigments in the thylakoids & include yellow, orange, & red

 

VII. Overview of Photosynthesis        6CO2 + 6H2O C6H12O6 + 6O2

  1. Photosynthesis is not a simple one step reaction but a biochemical pathway involving many steps
  2. This complex reaction can be broken down into  two reaction systems — light dependent & light independent or dark reactions
  • Light Reaction:         H2O O2 + ATP + NADPH2
    • Water is split, giving off oxygen.
    • This system depends on sunlight for activation energy.
    • Light is absorbed by chlorophyll a which “excites” the electrons in the chlorophyll molecule.
    • Electrons are passed through a series of carriers and adenosine triphosphate or ATP (energy) is produced.
    • Takes place in the thylakoids.
  • Dark Reaction:         ATP + NADPH2 + CO2 C6H12O6
    • Carbon dioxide is split, providing carbon to make sugars.
    • The ultimate product is glucose.
    • While this system depends on the products from the light reactions, it does not directly require light energy.
    • Includes the Calvin Cycle.
    • Takes place in the stroma.

VIII. Calvin Cycle

  1. Carbon atoms from CO2 are bonded or “fixed” into organic compounds during a process called carbon fixation
  2. The energy stored in ATP and NADPH during the Light Reactions is used in the Calvin cycle
  3. The Calvin cycle has 3 main steps occurring within the stroma of the Chloroplast

     STEP 1

  • CO2 diffuses into the stroma from surrounding cytosol
  • An enzyme combines a CO2 molecule with a five-carbon carbohydrate called RuBP
  • The six-carbon molecule produced then splits immediately into a pair of three-carbon molecules known as PGA

      STEP 2

  • Each PGA molecule receives a phosphate group from a molecule of ATP
  • This compound then receives a proton from NADPH and releases a phosphate group producing PGAL
  • These reactions produce ADP, NADP+, and phosphate which are used again in the Light Reactions.

   STEP 3

  • Most PGAL is converted back to RuBP to keep the Calvin cycle going
  • Some PGAL leaves the Calvin Cycle and is used to make other organic compounds including amino acids, lipids, and carbohydrates
  • PGAL serves as the starting material for the synthesis of glucose and fructose
  • Glucose and fructose make the disaccharide sucrose, which travels in solution to other parts of the plant (e.g., fruit, roots)

movements within plants

  • Glucose is also the monomer used in the synthesis of the polysaccharides starch and cellulose

  1. Each turn of the Calvin cycle fixes One CO2 molecule so it takes six turns to make one molecule of glucose

IX. Photosystems & Electron Transport Chain

  1. Only 1 in 250 chlorophyll molecules (chlorophyll a) actually converts light energy into usable energy
  2. These molecules are called reaction-center chlorophyll
  3. The other molecules (chlorophyll b, c, & d and carotenoids) absorb light energy and deliver it to the reaction-center molecule
  4. These chlorophyll molecules are known as antenna pigments
  5. A unit of several hundred antenna pigment molecules plus a reaction center is called a photosynthetic unit or photosystem
  6. There are 2 types of photosystems — Photosystem I & Photosystem II
  7. Light is absorbed by the antenna pigments of photosystems II and I
  8. The absorbed energy is transferred to the reaction center pigment, P680 in photosystem II, P700 in photosystem I
  9. P680 in Photosystem II loses an electron and becomes positively charged so it can now split water & release electrons  (2H2O   4H+   +   4e-   +  O2)
  10. Electrons from water are transferred to the cytochrome complex of Photosystem I
  11. These excited electrons activate P700 in photosystem I which helps reduce NADP+ to NADPH
  12. NADPH is used in the Calvin cycle
  13. Electrons from Photosystem II replace the electrons that leave chlorophyll molecules in Photosystem I

X. Chemiosmosis (KEM-ee-ahz-MOH-suhs)

  1. Synthesis or making of ATP (energy)
  2. Depends on the concentration gradient of protons ( H+) across the thylakoid membrane
  3. Protons (H+) are produced from the splitting of water in Photosystem II
  4. Concentration of Protons is HIGHER in the thylakoid than in the stroma
  5. Enzyme, ATP synthetase in the thylakoid membrane, makes ATP by adding a phosphate group to ADP

XI. Alternate Pathways

  1. The Calvin cycle is the most common pathway used by autotrophs called C3 Plants
  2. Plants in hot, dry climates use alternate pathways to fix carbon & then transfer it to the Calvin cycle
  3. Stomata are small openings on the underside of leaves for gas exchange (O2 & CO2)
  4. Guard cells on each side of the stoma help open & close the stomata
  5. Plants also lose H2O through stoma so they are closed during the hottest part of the day

  1. C4 plants  fix CO2 into 4-Carbon Compounds during the hottest part of the day when  their stomata are partially closed
  2. C4 plants include corn, sugar cane and crabgrass
  3. CAM plants include cactus & pineapples
  4. CAM plants open their stomata at night and close during the day so CO2 is fixed at night
  5. During the day, the CO2 is released from these compounds and enters the Calvin Cycle

XII. Factors Determining the Rate of Photosynthesis

  1. Light intensity – As light intensity increases, the rate of photosynthesis initially increases and then levels off to a plateau
  2. Temperature – Only the dark, not the light reactions are temperature dependent because of the enzymes they use (25 oC to 37oC)
  3. Length of day
  4. Increasing the amount of carbon dioxide available improves the photosynthesis rate
  5. Level of air pollution

 

 

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Pasteur Experiment

Recreation of Pasteur’s Experiment

Introduction:

Today, we take many things in science for granted. Many experiments have been performed and much knowledge has been accumulated that people didn’t always know. For centuries, people based their beliefs on their interpretations of what they saw going on in the world around them without testing their ideas to determine the validity of these theories — in other words, they didn’t use the scientific method to arrive at answers to their questions. Rather, their conclusions were based on untested observations.

Among these ideas, for centuries, since at least the time of Aristotle (4th Century BC), people (including scientists) believed that simple living organisms could come into being by spontaneous generation. This was the idea that non-living objects can give rise to living organisms. It was common “knowledge” that simple organisms like worms, beetles, frogs, and salamanders could come from dust, mud, etc., and food left out, quickly “swarmed” with life. For example:

Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times. Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs.

Objective:

In this experiment, you will conduct an experiment similar to the one done by Pasteur whenever he disproved spontaneous generation.

 

Materials Needed:Experiment Set-Up

  • Low-salt broth (chicken or beef, home-made or purchased)
  • 2  250-mL Erlenmeyer flasks
  • 2  1-hole rubber stoppers with bent glass tubing inserted (see diagram)
  • Glycerine
  • Hot plate & pot holders
  • 50-ml Graduated Cylinder
  • Marker

Procedure:

  1. Students should work in teams of 2 to 3 people. Each team should perform the following steps.
  2. Use glycerine and a twisting motion to insert glass tubing into the stoppers. be sure to rinse off excess glycerine with water.
  3. Mark Erlenmeyer flasks accordingly:
    1. Flask 1 with stopper and glass tube going straight up
    2. Flask 2 with stopper and glass tube bent in S-curve
  4. Using a graduated cylinder, place about 50-mL of broth in each Erlenmeyer flask.
  5. Place appropriate lids on flasks.
  6. Use a hot plate to boil broth in flasks with appropriate lids on them for 30 min., then let cool.
  7. For the next ten days, observe the flasks and record any changes in color, turbidity, smell, etc. (Be careful to NOT remove the stoppers from the flasks.)

Data:

Microbial Growth Record
Record the appearance of the flask contents.
Day Flask 1 with Straight Tubing Day Flask 2 with S-shaped Tubing
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10

Conclusion:

  1. What was the appearance on the broth in each flask on Day 1?
  2. Was their an observed appearance change in flask 1 over the 10 days? Describe the change, if any.
  3. Was their an observed appearance change in flask 2 over the 10 days? Describe the change, if any.
  4. Explain why there was or was not a change in the appearance of the broth in each flask.
  5. Why do you think the idea of spontaneous generation was believed to be true for so long (1000+ years)?
  6. Did your experiment support spontaneous generation of organisms? Explain why or why not?