Chapter 8

Question 1

what is the overall definition of photosynthesis

Answer 1

its a series of chemical reactions involved in the making of glucose

Question 2

what are two “groups” or “processes” involved in photosynthesis

Answer 2

light dependent and light independent

Question 3

in photosynthesis what is being reduced and what is being oxidized

Answer 3

the 6 molecules of carbon dioxide got reduced and 6 molecules of h2o got oxidized

Question 4

what are photoautoptrophs

Answer 4

make their own food during photosynthesis using solar energy this includes plants, algae, photosynthetic

Question 5

what are heterotrophs

Answer 5

use food made by somebody else aka animals, fungi, some protists, and photosynthetic bacteria .

Question 6

cuticle of plant

Answer 6

reduces H20 loss, secreted by the upper epidermis

Question 7

upper epidermis

Answer 7

like the skin of plant

Question 8

the mesophyll

Answer 8

contains many chloroplasts making it the layer most directly responsible for photosynthesis

Question 9

what is the vein

Answer 9

s a vascular structure (xylem and phloem cells surrounded by the bundle sheath) in a leaf that provides supports for the leaf and transports both water and food - (H20 and sugar) involved in photosynthesis in some plants if chloroplasts are found inside

Question 10

what is the stoma

Answer 10

its a small opening on the surface of the leaf that allows co2 to enter and o2 to exit.

Question 11

what is the guard cell

Answer 11

opens and closes the stoma

Question 12

what are the bundle sheath cells

Answer 12

protects the vein and is involved in photosynthesis in corn and sugarcane

Question 13

what are chloroplasts

Answer 13

they are directly involved in photosynthesis

Question 14

what are trichomas

Answer 14

they prevent leaves from overheating and from being eaten by herbivores; ribosomes leak from being overheated or eaten ex) Kiwi

Question 15

what are thylakoids

Answer 15

they are membrane bound compartments inside chloroplasts where light dependent reactions occur; they are found in the extracellular fluid of the chloroplasts

Question 16

what is the stroma

Answer 16

is extracellular fluid in the cell

Question 17

what is the thylakoid membrane

Answer 17

surrounds the thylakoid; similar to the inner mitochondrial membrane/matrix

Question 18

what is granum

Answer 18

stock of thylakoid

Question 19

what is unique about chloroplasts

Answer 19

they have a two membrane lipid bilayer; inner + outer

Question 20

what is the difference between the light dependent and light independent or the calvin cycle of photosynthesis

Answer 20

light dependent reactions are exergonic/catabolic, occur thylakoid membrane, requires, makes ATP, NADPH, O2
the Calvin the cycle/light independent occurs in the stroma, do not require sunlight, use ATP and NADH to synthesize sugars from CO2, its endergonic and anabolic, glyceraldehyde 3-phosphate (G3P) is a direct product of the Calvin cycle that is used to make glucose and other sugars

Question 21

what happens to electrons during photosynthesis

Answer 21

co2 gains lost electrons by h20 and gets reduced to glucose

Question 22

how do plants capture energy from the sun

Answer 22

through plant pigments that have molecules that capture solar energy and reflect different wavelengths

Question 23

what are the different pigments in plants that help them absorb the different wavelengths

Answer 23

chlorophyll a, b, and carotenoids

Question 24

what is the function of chlorophyll A and what color(s) does it reflect

Answer 24

C.A is the main photosynthetic pigment that absorbs violet-blue and red light but reflects green

Question 25

what is the function of chlorophyll B and what color(s) does it reflect

Answer 25

C.B is an accessory pigment that absorbs more blue and little bit of orange and red light but reflect green

Question 26

what is the function of carotenoids and what color(s) does it reflect

Answer 26

Carotenoid is also an accessory pigment that absorbs mostly blue and green light but reflect yellow, orange, and red light

Question 27

whats the difference between accessory pigments and main photosynthetic pigments

Answer 27

accessory pigments are not directly involved in photosynthesis, rather they’ll just pass energy from the sun to the main synthetic pigment chlorophyll A

Question 28

what happens in a photosystem

Answer 28

light energy from the sun in the from of a photon enters the photosystem and its moves around until a chlorophyll molecule of the antenna complex captures the photon and transfers energy in the form of electrons to the reaction center chlorophyll A molecule, electrons of the reaction center becomes excited and move to higher energy levels, go to an electrons center, and an electron donor resupplies the chlorophyll molecule with lost energy

Question 29

what happens when the days get shorter

Answer 29

when the days get shorter, there is no longer a need for the sun to be absorbed so chlorophyll molecules begin to break down/disappear

Question 30

how are the electrons in the reaction center replenished

Answer 30

first light transported from the antenna complex enters the chlorophyll A molecules, and chlorophyll A becomes very excited with high energy electrons, the high energy electrons are then given to an electron acceptor making the acceptor reduced and the chlorophyll A molecule oxidized. The lost electrons are then replenished by low energy electrons from an electron donor making th electron donor oxidized and now the chlorophyll A molecule reduced and the process starts again.

Question 31

What are the characteristics and functions of photosystem 2

Answer 31

photosystem 2 happens first, it is named 2 because it was discovered second. Electrons move from 2 - 1. The reaction center of chlorophyll a of P2. It uses high energy electrons to make atp and replaces lost electrons by oxidizing water/splitting it until it produces 1 oxygen atom. It absorbs light with a wavelength of 680 nm

Question 32

what are the characteristics and functions of Photosystem 1

Answer 32

It happens second in a light reaction despite its name and absorbs light with a wavelength of 700 nm; its antenna complex absorbs photons and moves them to the reaction center where electrons are absorbed and become high energy electrons which are then donated to an acceptor to make NADPH and an electron donator will replenish the lost energy of the chlorophyll molecule.

Question 33

how do both system replace lost electrons

Answer 33

photosystem two replaces its electrons from oxygen and photosystem one replaces its lost electrons from photosystem 2

Question 34

Break the light reaction process into a set of several steps

Answer 34

1) Sun Energy in the form of a photon enter the photosystem at 680 nm
2) The electrons from the sun are captured by a chlorophyll A through the movement of the antenna complex
3) water gets oxidized
4) the high energy electrons are donated to plastoquionine
5) the electrons oxidized from water replenish the lost electrons of the photosystem
6) PQ is the first mobile electron carrier and moves the electrons to the B6-F complex.
7) The b6-F complex uses the energy from the high energy electrons to pump H+ ions from the stroma (where H+ ions are low) to the thylakoid space where H+ ions are higher
8) the electrons are passed to plastocyanine which will deliver low energy electrons to photosystem 1 as a donor
9) Photosystem 1 then absorbs photons and undergoes the same processes as photosystem 2
10) high energy electrons are donated to ferredoxin and photosystem one is replenished with electrons from photosystem two
11) high energy electrons help NADP grab and a proton to make NADPH
12) protons from the B6f complex help activate atp synthase which catalyzes the phosphorylation of adp to make atp as H+ ions move from the thylakoid space back to the stroma ; passive facilitated diffusion

Question 35

what are the phases of the calvin cycle

Answer 35

phase 1 (carbon fixation) phase 2 (Reduction) and Phase 3 (regeneration of RuBP)

Question 36

explain what happens in the first phase and what enzymes are needed if any

Answer 36

6 molecule of co2 combines with 6 molecules of RuBP to produce 12 molecules of 3-phosphoglycerate; the enzyme used is rubisco (turns 6 times because of the 6 molecules)

Question 37

explain what happens in the second phase and what enzymes are needed if any

Answer 37

12 molecules of 3-phosphoglycerate are reduced to 1,3 biphosphoglycerate and then to glyceraldehyde 3-phosphate by first using 12 molecules of atp and 12 molecules of NADPH; 10 glyceraldehyde 3-phosphate continue the calvin cycle and 2 molecules leave the cycle to make sugars and glucose

Question 38

what happens in the last phase of the calvin cycle and what enzymes are needed if any

Answer 38

the ten molecules of glyceraldehyde 3-phosphate react with 6 molecules of atp to produce 6 molecules of ruBP and 4 molecules of inorganic phosphate

Question 39

why is hot/dry weather a problem for some plants

Answer 39

because when heat starts to enter the plant through the stomata/stoma it closes in an attempt to stop water from leaving while preventing co2 from entering the leaf and o2 from exiting therefore starting a buildup of 02 in the leaf which causes enzyme rubisco to bind to o2 instead of co2 which kickstarts photorespiration

Question 40

what is photorespiration

Answer 40

a respiratory process in many higher plants by which they take up oxygen in the light and give out some carbon dioxide, contrary to the general pattern of photosynthesis.

Question 41

why is photorespiration considered wasteful

Answer 41

because the enzyme rubisoc utilizes o2 as a substrate instead of co2 and thereforer produces no sugar or atp

Question 42

what plants can overcome photorespiration

Answer 42

C4 plants and CAM plants

Question 43

what are the differences between C4 and C3 plants

Answer 43

In C3 plants, the bundle sheath cells do not contain chloroplasts. In C4 plants, the bundle sheath cells contain chloroplasts. In C3 plants, the carbon dioxide fixation takes place only at one place. In C4 plants, the carbon dioxide fixation takes places twice (one in mesophyll cells, second in bundle sheath cells).

Question 44

what do C4 plants do to overcome photorespiration in the C4 pathway

Answer 44

the c4 pathway occurs in the mesophyll cells and to overcome this they keep their stoma/stomata slightly open throughout t he . day to allow a small flow of Co2 to react with PEP (phospheonelpyruvate) with the help of enzyme PEP carboxylase to form oxaloacetate. this forms malate

Question 45

what do C4 plants do to overcome photorespiration in C3 pathway

Answer 45

in the C3 pathway in the bundle-sheath cells wheree malate gets decarboxylated into Co2 and Pyruvate and pyruvate travels back into the mesophyll cells where its converted to phospheonal pyruvate to start the cycle again

Question 46

how many molecules of atp are needed for C4 plants in comparison to C3 plants

Answer 46

in the C4 pathway, 12 molecules of atp are neede dbecause its two per molecule of co2 and since there are 6 molecules of Co2 that need to be trasnported from the mesophyll cells to the bundle sheath cfells, 12 molecules are needed + the 18 from the clavin cycle making C4 plants in need for a total of 30 molecules of atp compared the 18 needed in C3 Plants

Question 47

where is rubisco found in C4 plants in comparison to C3 plants

Answer 47

C3 plants have rubisco in the mesophyll cells whereas rubisoc is found in the bundle-sheath cells for C4 plants

Question 48

what is a cam plant

Answer 48

cam plants do not have bundle sheath cells and photosynthesize the light dependent reaction in C3 plants at night.

Question 49

how do CAM plants overcome photorespiration

Answer 49

they keep their stoma/stomata open at night to let Co2 enter instead of the day time so there is less of a loss and then combine Co2 with PEP with the help of PEP carboxylase to make oxaloacetate…(same cycle from C4) until it enters the calvin cycle in the morning