17

Question 1

What is the equation for photosynthesis?

Answer 1

6CO2 + 6H2O gives C6H12O6 + 6O2

Question 2

Why is it incorrect to say energy is produced?

Answer 2

Energy cannot be created nor destroyed, only transferred.

Question 3

Why is ATP not a good energy storage molecule but organic molecules like carbs and lipids are?

Answer 3

• ATP is not very stable.
• It is easy to remove phosphate group.
• organic molecules are more stable
• organic molecules are more energy dense.

Question 4

Explain the interrelationship between respiration and photosynthesis in organisms

Answer 4

-In photosythesis, light energy is converted into chemical energy.

-Inorganic molecules are converted into organic molecules.

-Water and carbon dioxide are converted into glucose.

-Respiration uses oxygen produced in photosythesis.

-Organic molecules are broken down to inorganic molecules.

-Energy released is used to synthesise ATP, carbon dioxide produced is used in respiration

Question 5

Explain the importance of ATP to living organisms

Answer 5

-Universal energy currency

-Energy transfer is immediate.

-Energy is released small/usable quantities.

-Energy transfer is quick

-ATP can be resythesised

Question 6

Describe the properties of cell membranes necessary for the formation of a proton gradient

Answer 6

-Impermeable to ions/protons

-There can be different concentrations of protons on each side of a membrane

-Contains embedded proteins, e.g ATP synthase

Question 7

Name the type of diffusion which enables protons to move through ATP synthase and explain the role of ATP synthase in the production of ATP

Answer 7

Faciliated diffusion,
ATP synthase provides hydrophillic channel for diffusion of protons,
catalyses the synthesis of ATP,
lowers activation energy

Question 8

What is the process called of the primary synthesis of ATP in respiration and photosynthesis?

Answer 8

Chemiosmosis

Question 9

What does Chemiosmosis involve of?

Answer 9

The diffusion of protons from a region of high concentration to a region of low concentration through a partially permeable membrane.

Question 10

What two ways are electrons excited to higher energy levels?

Answer 10

• electrons present in pigment molecules are excited by absorbing light from sun.
• high energy electrons are released when bonds are broken in respiratory substrate molecules.

Question 11

What is an electron transport chain made of?

Answer 11

Electron carriers, each with progressively lower in energy levels.

Question 12

What are electron carriers made of?

Answer 12

Proteins

Question 13

How can protons move back through the membrane down the conc gradient?

Answer 13

Through a hydrophilic membrane linked to ATP synthase (enzyme) which catalyses the formation of ATP.

Question 14

What does autotrophic mean?

Answer 14

Plants that can photosynthesise like plants or algae.

Question 15

What does heterotrophic mean?

Answer 15

Organisms that eat other heterotrophic or autotrophic organisms to obtain complex organic molecules.

Question 16

Where does photosynthesis take place?

Answer 16

Chloroplast

Question 17

What is a chloroplast?

Answer 17

A chloroplast is an organelle found in plant and algae cells that is responsible for photosynthesis, converting light energy into chemical energy stored in glucose.

Question 18

What is the structure of a chloroplast?

Answer 18

A chloroplast has a double membrane: an outer membrane and an inner membrane, which surrounds a fluid-filled space called the stroma. Inside the stroma are thylakoids stacked into grana (singular: granum).

Question 19

What is the role of the outer membrane of the chloroplast?

Answer 19

The outer membrane of the chloroplast serves as a barrier and controls the movement of substances into and out of the chloroplast.

Question 20

What is the role of the inner membrane of the chloroplast?

Answer 20

The inner membrane of the chloroplast contains the ATP synthase enzymes and transport proteins necessary for photosynthesis and the movement of materials in and out of the stroma.

Question 21

What is the stroma in a chloroplast?

Answer 21

The stroma is a gel-like substance inside the inner membrane, containing enzymes for the Calvin cycle, as well as DNA, ribosomes, and chloroplasts’ own enzymes.

Question 22

What are thylakoids in chloroplasts?

Answer 22

Thylakoids are flattened membrane sacs within the chloroplast where the light-dependent reactions of photosynthesis occur. They contain chlorophyll and other pigments.

Question 23

What are grana in chloroplasts?

Answer 23

Grana (singular: granum) are stacks of thylakoids in the chloroplast. These stacks increase the surface area for the light-dependent reactions of photosynthesis.

Question 24

What is the function of chlorophyll in chloroplasts?

Answer 24

Chlorophyll is the green pigment found in thylakoid membranes. It absorbs light energy, mainly in the blue and red regions of the spectrum, to power the light-dependent reactions of photosynthesis.

Question 25

What are the light-dependent reactions in chloroplasts?

Answer 25

The light-dependent reactions occur in the thylakoid membranes, where light energy is absorbed by chlorophyll, generating ATP and NADPH, and releasing oxygen as a bi product.

Question 26

What are the products of the light-dependent reactions?

Answer 26

The products of the light-dependent reactions are ATP, NADPH, and oxygen (released as a byproduct from the splitting of water)

Question 27

What is the function of the Calvin cycle?

Answer 27

The Calvin cycle, also known as the light-independent reactions, takes place in the stroma. It uses ATP and NADPH from the light-dependent reactions to convert carbon dioxide into glucose.

Question 28

What is the role of the thylakoid membrane in photosynthesis?

Answer 28

The thylakoid membrane contains chlorophyll and other pigments that absorb light energy, and also hosts the ATP synthase enzyme, which helps synthesize ATP during photosynthesis.

Question 29

How are chloroplasts adapted for photosynthesis?

Answer 29

Chloroplasts are adapted for photosynthesis by having a large surface area provided by grana (for light absorption), a fluid-filled stroma (for enzyme activity in the Calvin cycle), and a double membrane structure for compartmentalization of processes.

Question 30

What is the role of the chloroplast’s DNA?

Answer 30

Chloroplasts contain their own DNA, which encodes some of the proteins required for photosynthesis, allowing them to replicate independently of the cell’s nuclear DNA.

Question 31

What is the function of the membrane proteins in the thylakoid membrane?

Answer 31

The membrane proteins in the thylakoid membrane are involved in the electron transport chain, helping to move electrons and create the proton gradient necessary for ATP synthesis.

Question 32

How do chloroplasts generate ATP?

Answer 32

Chloroplasts generate ATP during the light-dependent reactions of photosynthesis, when protons (H+) flow through the ATP synthase enzyme in the thylakoid membrane due to a proton gradient created by the electron transport chain.

Question 33

How does the structure of chloroplasts enable efficient photosynthesis?

Answer 33

The large surface area of the grana increases the number of thylakoid membranes for light absorption, while the stroma contains the necessary enzymes for carbon fixation in the Calvin cycle. The double membrane provides compartmentalization for distinct stages of photosynthesis.

Question 34

What is the role of NADP+ in chloroplasts?

Answer 34

NADP+ is the electron carrier in the light-dependent reactions. It combines with electrons and protons to form NADPH, which is used in the Calvin cycle to reduce carbon dioxide to glucose.

Question 35

What are the main types of chlorophyll?

Answer 35

The main types are chlorophyll a (primary pigment in photosynthesis) and chlorophyll b (accessory pigment that aids chlorophyll a by absorbing light in different wavelengths).

Question 36

How does chlorophyll absorb light?

Answer 36

Chlorophyll absorbs light most effectively in the blue and red regions of the spectrum and reflects green light, giving plants their color.

Question 37

What is the role of chlorophyll a in photosynthesis?

Answer 37

Chlorophyll a is the primary pigment involved in photosynthesis, absorbing light energy and using it to excite electrons in the light-dependent reactions.

Question 38

How does chlorophyll b support photosynthesis?

Answer 38

Chlorophyll b absorbs light in the blue and red-orange parts of the spectrum and transfers the energy to chlorophyll a, enhancing the efficiency of light absorption.

Question 39

What happens when chlorophyll absorbs light?

Answer 39

Light energy excites electrons in chlorophyll, which are then passed through the electron transport chain to produce ATP and NADPH.

Question 40

What is photolysis, and how does it involve chlorophyll?

Answer 40

Photolysis is the splitting of water molecules using light energy, facilitated by chlorophyll. This releases oxygen, protons, and electrons that are used in the light-dependent reactions.

Question 41

What is the role of chlorophyll in ATP and NADPH production?

Answer 41

Chlorophyll absorbs light energy, which excites electrons that create a proton gradient for ATP production and reduce NADP+ to form NADPH.

Question 42

Why is chlorophyll important for photosynthesis efficiency?

Answer 42

Chlorophyll’s ability to absorb light energy and transfer it to reaction centers in photosystems is crucial for the efficiency of photosynthesis, enabling plants to convert light into chemical energy.