Genbio 1 Q1 MOD3 OF 8 In Light, There is Life PDF

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SENIOR HIGH SCHOOL

General Biology 1 Module 3 In Light, There is Life

General Biology I Self-Learning Mode (SLM) Module 3: In light, There is Life First Edition, 2020 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalties. Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included in this module are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and authors do not represent nor claim ownership over them.

Development Team of the Module Writers: Haydee Carumba-Parreño, and Elvina L. Taran Editors: Leoncio P. Tan, Lenie G. Forro, and Cynthia S. Bustillo Reviewers: Yusof A. Aliudin, Agabai S. Kandalayang, Sheryl B. Bautista, Aida S. Delon, Rowena P. Alterado, Ma.Kristine B. Latris, and Eloisa R. Agni Layout Artist: Glen D. Napoles, Jay Ar O. Espartero, Alex C. Macale, and Mark Daryl T. Lazaro Management Team: Allan G. Farnazo - Regional Director Isagani S. Dela Cruz - Schools Division Superintendent Natividad G. Ocon - Assistant School Division Superintendent Gilbert B. Barrera – Chief, CLMD Arturo D. Tingson, Jr. – REPS, LRMS Peter Van C. Ang-ug – REPS, ADM Elpidio B. Daquipil – CID Chief Juvy B. Nitura – EPSVR, LRMS Lenie G. Forro – EPSVR, Science Coordinator Marcelo B. Bocatera- ADM Coordinator Printed in the Philippines by Department of Education – SOCCSKSARGEN Region Office Address: Telefax: E-mail Address:

Regional Center, Brgy. Carpenter Hill, City of Koronadal (083) 2281893 [email protected]

Introductory Message For the facilitator: Welcome to the General Biology I Self-Learning Module (SLM) on In Light, There is Life This module was collaboratively designed, developed and reviewed by educators both from public and private institutions to assist you, the teacher or facilitator in helping the learners meet the standards set by the K to 12 Curriculum while overcoming their personal, social, and economic constraints in schooling. This learning resource hopes to engage the learners into guided and independent learning activities at their own pace and time. Furthermore, this also aims to help learners acquire the needed 21st century skills while taking into consideration their needs and circumstances. In addition to the material in the main text, , Notes to the Teachers are also provided to the facilitators and parents for strategies and reminders on how they can best help you on your home-based learning. Please use thus module with care. Do not put unnecessary marks on a any part of this SLM. Use a separate sheet of paper in answering the exercises and tests. Read the instructions carefully before performing each task. If you have any questions in using this SLM or any difficulty in answering the task in this module, do not hesitate to consult your teacher or facilitator. Thank you.

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What I Need to Know Hello! How are you? Good thing that we are still alive and thankful for the opportunity to again see the beauty of a sunrise. Whatever our breakfast this morning, be it fish, meat, or veggies, all of these get their energy from the sun. Photosynthesis is the process by which plants, some bacteria, and other protists convert light energy (sun) into chemical energy (food). We call these organisms producers. They make their own food and feed the consumers who cannot produce their own food. The oxygen that we breathe every day, is a by-product of photosynthesis. Most Essential Learning Competency: Describe the patterns of electron flow through light reaction events (STEM_BIO11/12-IIa-j-4).

After going through this module, you are expected to: 1. differentiate the two stages of photosynthesis; 2. identify the important molecules involved in the light reactions; and 3. describe the events and processes happening during light reactions.

What I Know Directions: Choose the letter of the correct answer and write it on a separate sheet of paper. 1.

What A. B. C. D.

is the correct chemical equation for photosynthesis? 6 H2O + 6 CO2 = C6H12O6 + 6 O2 6 H2O + 6 O2 = C6H12O6 + 6 CO2 C6H2O6 + + 6 O2 = 6 H2O + 6 CO2 C6H12O6 + + 6 O2 = 6 H2O + 6 CO2

2.

What A. B. C. D.

cell organelle performs PHOTOSYNTHESIS? Chloroplast Cytoplasm Mitochondria Ribosomes

3.

Where does light-dependent reaction take place? A. Lumen B. Stroma C. Thylakoids D. Outer membrane

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4.

What A. B. C. D.

is the primary function of the light reactions of photosynthesis? To excite electron To absorb sunlight To produce carbohydrates To produce NADPH and ATP

5.

What A. B. C. D.

supplies the electrons for the Light Reactions? Water Oxygen Carbon dioxide ATP and NADP+

6.

Which of the following is NOT produce in the light reactions? A. ATP B. Glucose C. NADPH D. Oxygen

7.

What A. B. C. D.

stage of photosynthesis the splitting a molecule of water occur? Calvin Cycle Dark Reaction Photosystem 1 of the light dependent reaction Photosystem 2 of the light dependent reaction

8.

What A. B. C. D.

supplies the electrons that are lost in photosystem I (PSI)? Water Oxygen Glucose The electrons from PS II

9.

What is the function of NADP+ in the light reaction? A. It absorbs light. B. It is an electron carrier. C. It is a light-reflecting pigment. D. It acts as long-term energy storage.

For items 10 and 11. Please refer to the illustration below.

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10. Using the given illustration, which of the following are the products of the light reactions that are needed for the Calvin cycle? A. B. C. D.

ADP and ATP ATP and NADPH Oxygen and sugar NADP + and NADPH

11. Based on the illustration above, for light reaction to happen, which of the following things are needed? A. ATP and NADPH B. Oxygen and sugar C. Water and sunlight D. Sunlight and chlorophyll 12. How is Photosystem II differ from Photosystem I? A. Photosystem II contains P680 a while photosystem I contains P700. B. Photosystem traps light energy while photosystem does not need light energy C. Photosystem II contains chlorophyll a while photosystem I contains Carotenoid. D. Electron passes through electron transport chain in Photosystem II while electron stops at reaction center in Photosystem I. 13. Which of the following statements is TRUE about the importance of light reaction to humans?

I.

It manufactures glucose for energy.

II. It produces oxygen which humans inhale. III. It releases carbon dioxide which humans breathe out. IV. It splits water and releases hydrogen to the atmosphere.

A. II only B. I and III only C. I, II, and III only D. I, II and IV only

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14. Paul is biology major student. He is discussing light reaction in their class. After his presentation, he was asked by his professor about the function of NADP+ during light reaction. Paul answered that NADP+ acts an electron carrier. Do you think his answer is correct? A. No, the NADPH carries electrons not NADP+. B. No, the NADP+ carries protons not electrons. C. Yes, the NADP+ carries electrons to form ATP. D. Yes, the NADP+ carries electrons to form NADPH.

15. Ella would like to know about how adenosine triphosphate is formed. During her research, she found out during chemiosmosis, an enzyme known as ATP synthase creates adenosine triphosphate (ATP) from ADP. Do you think the information is correct? A. Yes, ATP synthase forms ATP and ADP. B. No, ATP synthase breaks down ATP and NADPH. C. No, ATP synthase breaks down NADPH to form ATP. D. Yes, ATP is formed from ADP with the help of enzyme ATP synthase.

What’s In

Hi, how are you today? In the previous module, you had a good understanding of the importance of chlorophyll and other pigments in photosynthesis. Chlorophyll A is the primary pigment that reflects green light and absorbs red and blue light. There are also other types of chlorophyll and pigments including red, brown, and blue which help channel light energy to chlorophyll A or protect the cell from photodamage. Chlorophyll pigments are present in the chloroplast where lightdependent reactions also taking place. Light-dependent reactions capture light energy to produce ATP and NADPH. Activity 1. Know Me Well Directions: Copy the illustration of chloroplast below in separate sheet of paper. Label each part as indicated by the number. Refer your answer to the parts with their functions that are found inside the box. Outer membrane

- outer covering of chloroplast

Inner membrane

- forms a border to the stroma

Stroma

- fluid portion of the chloroplast; space outside the thylakoids

Thylakoid

- disc-like structure where light reaction takes place

Granum

- stack of thylakoids

Lumen

- interior of the thylakoid

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Figure 1. Parts of Choloroplast

What’s New Hello there! Photosynthesis comes in two stages- the light dependent reaction, which requires light, and the light independent reaction, which does not require light. In this module, we will expand our understanding on photosynthesis by investigating how light-dependent reactions take place during photosynthesis in plants. We will further discover what pigment molecules absorbed light, how excited electrons pass through reaction center and eventually to an electron transport chain, and how the energetically "downhill" flow of electrons synthesize ATP and NADPH. Before we get into the details of the light-dependent reactions, let’s find out the difference between light reactions and dark reactions (a.k.a. Calvin Cycle). You better read and understand the conversations of the two strangers below for you to perform the task given. One foggy morning, as you walk along the beach, you heard the conversations of two individuals following your back. It seemed that they are strangers to one another. Calvin Cycle Light Reactions

: “It’s a nice morning”. : “Yes, it is a nice and cool morning indeed.

Calvin Cycle

: “I’m Calvin Cycle”, (a voice of a male you heard)

Light Reactions

: “I’m Light Reactions” (replied by a voice coming from a girl)

Calvin Cycle

: “Do you live around here or are you visiting?”

Light Reactions

: “I’m visiting from Thylakoid, a place within Granum”. How about you?”

Calvin Cycle

: “Oh, we’re only neighbors!”

Light Reactions

: “Really? Where are you from?”

Calvin Cycle

: “I live in the Stroma, a city outside Thylakoid. You’ve been so generous in sending me ATP and NADPH. Together with CO2,

I used them to produce glucose (sugar). You’re such an angel! I really appreciate your kindness. I’m so thankful for that” Light Reactions

: “No, That’s nothing. Those ATP and NADPH came from ADP+P

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and NADP+ that you sent me. I only restored them to their high energy forms (ATP and NADPH). By the way, I’m going home in Thylakoid next week. Do you like to visit my place?” Calvin Cycle

: “What’s a good thing to see in your place?”

Light Reactions

: “I recommend going to the east where sunlight strikes and to

the west where water drops. Sunlight and water gave me energy to produce ATP and NADPH and Oxygen as byproduct which humans need”. Calvin Cycle : That’s great. I never had a chance to see a photon of light in my life. It would also be so exciting to see a molecule of water for

the

first time. Light Reactions : Oh, my friend is waiving at me right there. I hope you enjoy your stay here. Well, it was nice meeting you by the way. I hope

you

have a goodtime here. Calvin Cycle : Thanks for inviting me. It was nice talking to you. See you around. Activity 2. Have You Heard Me Right? Directions: In a separate sheet of paper, draw and label the diagram below to summarize the two stages of photosynthesis. Recall the conversations that you just heard from two strangers. Use the word bank for the answer. Word bank: Thylakoids

Calvin cycle

CO2

NADP+

granum

light

NADPH

O2

stroma

H2O

ATP

ADP + P

light reactions

sugar

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Figure 2. Stages of Photosynthesis.

Activity 3. Paint Me Up

Directions: Copy the illustration on a separate sheet of paper. Color the diagram below as described: -

Color the energy from sunlight YELLOW Label PHOTOSYSTEM I AND II

-

Color the two photosystems GREEN

-

Color the hydrogen ions PINK - Color the electrons RED

-

Color ATP Synthase ORANGE

-

Color the phospholipid of the thylakoid membrane BLUE

Figure 3. Light Dependent Reactions.

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What is It Chemical Reaction for Photosynthesis: 6 CO2 + 6 H20 + sunlight + C6H12O6 + 6 O2 Table 1. Distinguishing Two Stages of Photosynthesis. Light-Dependent Reactions

Light-Independent Reactions

Site of the process

thylakoid

stroma

Light dependence

Needs sunlight

Does not need sunlight

Source of energy

sunlight

ATP

Reducing agent

Reduce NADP+ to NADPH

Reduce C02 to sugar C6H12O6

reactants

Water, NADP+, ADP, Pi

Carbon dioxide, ATP, NADPH

products

Oxygen, ATP, NADPH

Glucose, NADP+, ADP, Pi

Light- Dependent Reactions of Photosynthesis: Linear Electron Flow The process involves in converting light energy into chemical energy takes place in a multi-protein complex called a photosystem. Two types of photosystems are embedded in the thylakoid membrane: photosystem II (PSII) and photosystem I (PSI). Each photosystem plays a key role in capturing the energy from sunlight by exciting electrons. These energized electrons are transported by “energy carrier” molecules, which power the light-independent reactions. Photosynthetic pigments like chlorophyll a, chlorophyll b and carotenoids are found in the thylakoid membranes of the chloroplast. This reaction can be found in green plants.

Figure 4. Light Dependent Reactions in Thylakoid.

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Diagram of Light-Dependent Reactions in thylakoid

Figure 5. The Linear Light Reactions. The Steps or Events in Light Reactions. 1. Pigment molecules of the light-harvesting complex of Photosystem II (inner surface of thylakoid) absorb light energy (photon) until the energy reaches the reaction center. The energy is then absorbed by pigment 600 (P680) pair of chlorophyll a, energizing the electron to high energy level. 2. The high-energy electron is passed to the primary electron acceptor, pheophytin. The electron of P680 is lost then becomes positively charged (P680+). 3. Electrons from a water molecule is attracted by the positively charged molecule (P680+) which results to H20 being split up into two electrons, two hydrogen ions (H+), and an oxygen atom with the provision of light energy. This oxygen atom then instantly combines with another oxygen atom to produce an oxygen molecule (O2) which is then released outside through the leaf’s stomata. 4. The excited electrons travelled through the electron transport chain from the primary electron acceptor to the electron carrier molecules the plastoquinone (Pq), a cytochrome complex, and plastocyanine (Pc), releasing energy as it goes. until they enter Photosystem I. 5. Some of the released energy are used to pump hydrogen ions from the stroma to the lumen, building a proton gradient. There is an uneven distribution of hydrogen ions in the stroma and lumen which is the result of H2O molecules splitting up. Trying to equalize the distribution, H+ ions move from the lumen to the stroma passing through ATP synthase, driving the production of ATP from ADP. This process is called chemiosmosis. 6. On the other hand, photon (light energy) is absorbed by pigment molecules until the energy arrives at the reaction center complex of Photosystem I (outer

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surface of thylakoid). This energy makes the electron present in the pair of pigment 700 (P700) chlorophyl a excited. The excited electron is then passed on to the primary electron acceptor which makes the P700 positively charged (P700+) and now looks for electrons to fill up the missing ones. This is filled up by the electrons from Photosystem II that are transferred through the electron transport chain. 7. The photo-excited electron from the primary electron acceptor of Photosystem I enters another electron transfer chain, transferring the electron to the ironcontaining protein ferredoxin (Fd). 8. The enzyme NADP+ reductace passes the electron to NADP+ and stabilizes it by adding a proton (H+) to produce NADPH. NADPH is released to the stroma and becomes part of the Calvin Cycle.

Directions. Write the table below in a separate sheet of paper. Complete each cell with appropriate answer(s). Choose the answer from the box following herein: -Inner surface of thylakoid -Outer surface of thylakoid -Pair of pigment 700 (P700) -Pair of pigment 680 (P680)

-Light energy and water -Light energy -Oxygen and ATP -NADPH

-water -PSII

Table 2. Distinguishing Parts of Light Reactions Photosystem II

Photosystem I

Location Reactants Product(s) Source of electron Types of chlorophyll pigment that receives electron at the reaction center Cyclic Electron Flow Under certain condition, the photo-excited electrons may take a shortcircuited route called Cyclic Electron Flow, which utilizes Photosystem I (P700) but not Photosystem II (P680). The ferredoxin goes back to the cycle and passes the electron to the cytochrome complex and to the Pc until it reaches P700 chlorophyll instead of transferring the electron to NADP+ reductase. Due to this event, no NADPH is produced but ATP is still synthesized. This takes place in bacteria and green plants.

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Figure 6. The Cyclic Electron Flow. Directions: Copy the table in a separate sheet of paper. Fill in each cell in the table with appropriate descriptions of Linear/Non-cyclic Electron Flow and Cyclic Electron Flow. Select from the choices given in the box below: -Only PSI is involved -photolysis of water is required -oxygen is released -ATP and NADPH is synthesized

-both PSI and PSII are involved -water is not required -no oxygen is released -only ATP but not NADPH is synthesized

Table 3. Distinguishing Cyclic and Non-cyclic Electron Flow

Linear/Non-cyclic Electron Flow

Cyclic Electron Flow

What’s More Directions: Rearrange in sequence the following steps of light reactions by writing the numbers only. Answer this on a separate sheet of paper. 1. The excited electrons are then transferred through the electron transport chain thru electron carrier plastoquinone (Pq), a cytochrome complex, and plastocyanine (Pc).

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2. The enzyme NADP+ reductace passes the electron to NADP+ and stabilizes it by ...