Ch. 10 Photosynthesis

Question 1

What are autotrophs?

Answer 1

“Self-feeders” they sustain themselves without eating anything derived from other living beings

Plants 🌱

Question 2

What are heterotrophs?

Answer 2

Unable to make their own food; live on compounds produced by other organisms “other feeder” eat living organism (plant or animal)

Question 3

Is photosynthesis carried out by autotrophs or heterotrophs?

Answer 3

Autotrophs

Question 4

What were the earliest organisms to carry out photosynthesis?

Answer 4

Cyanobacteria

Question 5

What is the balanced equation for photosynthesis?

Answer 5

6 CO2 + 12 H2O -> C6H12O6 + 6 O2 + 6 H2O + Light energy

Question 6

Where do the reactants of photosynthesis enter plants?

Answer 6

Stomata: small openings in their leaves

Xylem cells: transport water and minerals from roots to the rest of the plant

Question 7

Where do the products of photosynthesis exit from plants?

Answer 7

Stomata: small regulated openings in their leaves

Phloem cells: transport sugars from leaves to the rest of the plant

Question 8

How are water and minerals transported from roots to the rest of the plant?

Answer 8

Through Xylem cells

Question 9

How is sugar transported from leaves to the rest of the plant?

Answer 9

Through Phloem cells

Question 10

Where in the plant does photosynthesis occur?

Answer 10

In chloroplasts, most photosynthesis takes place in leaves

Question 11

What is the relationship between the length of a wavelength and the energy it carries?

Answer 11

Longer wavelengths have lower energy

Shorter wavelength have higher energy

Question 12

What are pigments?

Answer 12

Pigments are molecules which absorb certain wavelengths of visible light and reflect other wavelengths

Question 13

What are the main pigments used in photosynthesis?

Answer 13

Chlorophyll A and Chlorophyll B

Question 14

What does an absorption spectrum show?

Answer 14

Absorption of light by chloroplast pigments (Chlorophyll A, Chlorophyll B, and Carotenoids)

Question 15

What does an action spectrum show?

Answer 15

Rate of photosynthesis

Question 16

What type of relationship exists between the two spectra?

Answer 16

In graph on slide 12 the rate of photosynthesis and light absorbed are low in this same area where green is and high between purple and blue

Question 17

What is the relationship between the wavelength(s) a pigment absorbs, and the color(s) the pigment reflects?

Answer 17

Leaves appear green because chlorophyll reflects and transmits (does not absorb) green light.

Question 18

What happens when a photon of light strikes a photosynthetic pigment?

Answer 18

An electron within the molecule becomes excited (jumps up)

Question 19

What happens to the excited electron?

Answer 19

The excited electron may be passed on to another molecule or return to ground state

Question 20

What is the relationship between the light reactions and the Calvin Cycle in photosynthesis?

Answer 20

The light reactions provide ATP and NADH to the Calvin Cycle

Question 21

Understand that H atoms split to form electrons (e-) and protons (H+).

Answer 21

H gain/loss represents electron gain/loss in these oxidation-reduction reactions.

Question 22

During photosynthesis, water is oxidized and carbon dioxide is reduced. This happens through two major oxidation/reduction reactions which are…

Answer 22

During light reactions and The Calvin Cycle

Question 23

During the light reactions…

Answer 23

H2O is oxidized (O2 remains), and NADP+ is reduced (this forms NADPH)

Question 24

During the Calvin Cycle…

Answer 24

NADPH is oxidized (NADP+remain), and CO2 is reduced (this forms CH2O, a sugar) Some oxygen from the CO2 is reduced to create new H2O molecules

Question 25

What is a photosystem?

Answer 25

A light-capturing unit located in the thylakoid membrane of the chloroplast consisting of a reaction-center complex surrounded by numerous light-harvesting complexes. There are two types of photosystems, I and II; they absorb light best at different wavelengths.

Question 26

What occurs in a photosystem?

Answer 26

A proton strikes a pigment molecule in a light-harvesting complex, the energy is passed from molecule to molecule until it reaches the reaction-center complex

Question 27

Where do the light reactions take place? Be specific.

Answer 27

Takes place in the Thylakoid inside the Chloroplast

Question 28

Photosystem II: What molecules DIRECTLY supply the electrons which go through the electron transport chains? Be specific.

Answer 28

Water (H2O), electrons comes from the splitting of water molecule

Question 29

Photosystem II: What replenishes the electron lost by the chlorophyll molecule in Photosystem II? Be specific

Answer 29

Electrons are replenished by H atoms from splitting of water molecules

Question 30

Photosystem II: What happens to the energy generated when the electrons go through the electron transport chain?

Answer 30

Electrons are passed by the protein in the membrane and they give off energy (ATP)

Question 31

Photosystem II From where are the protons pumped? Where are they pumped to? And, where do they diffuse back to?

Answer 31

Protons come from the H atom (hydrogen) in the splitting of water. They are pumped into the Thylakoid Space (inner thylakoid). They are diffused to the ATP synthase and back into the Calvin Cycle

Question 32

Photosystem II: What protein molecule (enzyme) do the protons diffuse through which releases the energy to rebuild ATP?

Answer 32

ATP synthase

Question 33

Photosystem I: What replenishes the electron lost by the chlorophyll molecule in Photosystem I? Be specific.

Answer 33

Electrons are replenished by electrons in the electron transport chain.

Question 34

Where does the Calvin Cycle take place? Be specific.

Answer 34

ATP and NADPH are produced in the stroma, where the Calvin cycle takes place

Question 35

What does “carbon fixation” mean?

Answer 35

The process by which photosynthetic organisms convert inorganic carbon in the atmosphere into organic carbon compounds used by living organisms

Question 36

At the beginning of the Calvin Cycle, what molecule does CO2 join?

Answer 36

Ribulose biphosphate (RuBP)

Question 37

What enzyme catalyzes this reaction?

Answer 37

RuBisCO

Question 38

What two 3-carbon molecules are produced?

Answer 38

3-Phosphoglycerate

Question 39

What molecule is oxidized in order for reduction to take place? What is produced as the result of reduction?

Answer 39

NADPH is oxidized and an organic compound is reduced to form Glyceraldehyde-3-phosphate (G3P), a sugar

Question 40

What sugar (carbohydrate) is produced by the cycle? How many carbons does this sugar have?

Answer 40

G3P, contains 3 carbon

Question 41

What molecule is regenerated at the end of the cycle?

Answer 41

RuBP

Question 42

What are the three phases of the Calvin Cycle?

Answer 42

1. Carbon fixation (inorganic carbon is converted to organic carbon) 2. Reduction (NADPH oxidized + organic compound reduced = G3P 3. Regeneration of RuBP, the CO2 acceptor