photosynthesis

Question 0

equation for photosynthesis (symbols)

Answer 0

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

Question 1

define autotrophs and hererotrophs

Answer 1

autotrophs: an organism that makes their own nutrients from food
heterotrophs: eats other organisms to get nutrients

Question 2

photosynthesis equation (words)

Answer 2

Carbon dioxide + water + light energy –> glucose + oxygen

Question 3

explain how we know that the oxygen released in photosynthesis comes from water. use 18O as the basis of the discussion

Answer 3

oxygen released from photosynthesis come from water with the use of 18 O as a traced to follow the fate of oxygen atoms during photosynthesis. the experiments showed that the O2 from plants was labeled with 18 O only if water was the source of the tracer

Question 4

explain what occurs in the light reactions stage of photosynthesis

Answer 4

water is split giving off O2 as a by-product. chlorophyll absorbs light and drives a transfer of the electrons and hydrogen ions from water to an acceptor called NADP+ where they are temporarily stored. light reactions also generate ATPS by photophorylation

Question 5

explain the Calvin cycle

Answer 5

the cycle begins by incorporating CO2 from the air into organic molecules already present in the chloroplast. this initial incorporation of carbon into organic compounds is known as carbon fixation. the Calvin cycle then reduces the fixed carbon to carbohydrate by the addition of electrons. the reducing power is provided by NADPH. to convert CO2 to carbohydrate, the Calvin cycle also requires chemical energy in the form of ATP.

Question 6

what are the colors of the visible spectrum

Answer 6

red orange yellow green blue indigo violet

Question 7

notice the color and corresponding wavelengths and then explain the relationship between wavelength and energy

Answer 7

electromagnetic energy travels in rhythmic waves analogous to those creating by dropping a pebble into a pond. electromagnetic waves are disturbances of electric and magnetic fields rather than disturbances of amaterial medium such as water

Question 8

explain the correlation between an absorption spectra and an action spectrum

Answer 8

absorption spectrum is the range of a pigments ability to absorb various wave lengths of light
action spectrum is a graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process

Question 9

explain how Englemann was able to form an action spectrum long before the invention of a spectrophotometer

Answer 9

he used aerobic bacteria, which concentrate near an oxygen source
, to determine which segments of the alga were releasing the most O2 and thus photosynthesizing most. bacteria congregated in greatest numbers around the parts of parts of the alga illuminated with violet-blue or red light

Question 10

a photo system is composed of a protein complex called a ____-____ complex surrounded by several ___-___ complexes

Answer 10

reaction-center

light-harvesting

Question 11

reaction center complex-

Answer 11

• this complex of proteins associated with a special pair of chlorophyll a molecules and a primary electrons acceptor. located centrally in a photo system, this complex triggers the light reactions of photosynthesis. excited by light energy, the pair of chlorophyll a donates and electron to the primary electron acceptor, which passes an electron to and electron transport chain

Question 12

light-harvesting complex

Answer 12

this complex of proteins associated with pigment that captures light energy and transfers it to reaction-center pigments in a photosystem

Question 13

primary electron acceptor

Answer 13

in a thylakoids membrane of a chloroplast or in the membrane of some prokaryotes, the primary electron acceptor is a specialized molecule that shares the reaction center complex with s pair of chlorophyll a molecules and that accepts an electron from them

Question 14

what is the source of energy that requires the electron in photosystem 2

Answer 14

light

Question 15

what compound is the source of electrons for linear electron flow? this compound is also the source of ____ in the atmosphere

Answer 15

water; splitting of water

Question 16

as electrons fall between photosystem 1 and 2, the cytochrome complex uses the energy to pump ___ ions. this builds a proton gradient that is used in chemiosmosis to produce what?

Answer 16

hydrogen; ATP

Question 17

in photosystem 2, the excited electron is eventually used by NADP+ reductase to join NADP+ and a H+ to form ____

Answer 17

NADPH

Question 18

in cyclic electron flow no water is split, there is no production of ___, and there is no release of ____

Answer 18

NADPH; oxygen

Question 19

use four examples to compare how chemiosmosis is similar in photosynthesis and cellular respiration

Answer 19

1. electron transport chain assembled
2. phosphorylation
3. inner membrane of the mitochondria pumps protons from mitochondria matrix out the the intermembrane. the thylakoids membrane of the chloroplast pumps protons from the storms into the thylakoid space
4. proton diffuse through ATPS synthase

Question 20

use two key differences to explain how chemiosmosis is different in photosynthesis and cellular respiration

Answer 20

(chemiosmosis) electron that are dropped down the transport chain are from organic molecules; electron are from water (photosynthesis)
chloroplasts do not need molecules from food to make ATP

Question 21

list the three places in light reactions where a proton-motive force is generated

Answer 21

1. water is split by photosystem 2
2. Pq transfers electrons to the cytochrome complex, 4 protons are translocated across the membrane into the thylakoid space
3. hydrogen ions is removed from the stra when it is taken up by NADP+

Question 22

the carbohydrate produced directly from the Calvin cycle is not glucose, but the three-carbon compound ___. each turn of the Calvin cycle fixes in molecule of CO2; therefore, it will take ___ turns of the Calvin cycle to net one G3P

Answer 22

glyceraldehyde 3-phosphate (G3P); 3

Question 23

explain the important events that occur in the carbon fixation stage of the Calvin cycle

Answer 23

the Calvin cycle incorporates each CO2 molecule, one at a time, by attaching it to a five-carbon sugar names ruby lose bus phosphate. the enzyme that catalyzes this first step is RuBP carboxylasd, or Rubisco. the product of the reaction is six-carbon intermediate so unstable that it immediately splits in half, forming two molecules of 3-phosphoglycerate

Question 24

the enzyme responsible for carbon fixation in the Calvin cycle, and possibly the most abundant protein in Earth, is ___.

Answer 24

rubisco

Question 25

I’m phase two, the reduction stage, the reducing power of ___ will donate electrons to the low-energy acid 1,3-bisphosphoglycerate to form the three-carbon sugar ___.

Answer 25

NADPH; G3P

Question 26

the Calvin cycle must be turned three times. each turn will require a starting molecule of ribulose bisphosphate, a five-carbon compound. this means we start with ___ carbons distributed in three RuBPs. after fixing three carbon dioxides using the enzyme ___, the Calvin cycle form six G3Ps with a total of ___ carbons. at this point the net gain of carbons is __, or one net G3P molecule.

Answer 26

15; rubisco; 18; 3

Question 27

explain how the regeneration of RuBP is occimplished

Answer 27

in a complex series of reactions, the carbon skeletons of five molecules of G3P are rearranged by the last steps of the Calvin cycle unto three molecules of RuBP. the cycle spends 3 more molecules of ATP. the RuBP is now prepared to receive CO2 again, and the cycle continues

Question 28

the net production of one G3P requires ___ molecules of ATP and ___ molecules of NADPH.

Answer 28

9; 6

Question 29

explain what is meant by a C3 plant

Answer 29

a plant that uses the Calcun cycle for the initial steps incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate

Question 30

what happens when a plant undergoes photorespiration

Answer 30

during photorespiration, which is a metabolic process, the plant consumes oxygen and ATPS, which releases carbon dioxide, and decreases photosynthetic output

Question 31

explain how photorespiration can be a problem in agriculture

Answer 31

rice, wheat, and soybeans are C3 plants that are important in agriculture. when their stomata partially close on hot, dry days, C3 plants produce less sugar because the declining level of CO2 in the leaf starves the Calvin cycle, limiting growth

Question 32

explain what is meant by a C4 plant

Answer 32

a plant in which the Calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle

Question 33

explain the role of PEP carboxylasd in C4 plants, including key differences between it and rubisco

Answer 33

this enzyme adds CO2 to phosphoenolpyruvate (PEP), forming the four-carbon product oxaloactetate. PEP carboxylase has a much higher affinity for CO2 than does rubisco and no affinity for O2. therefore, PEP carboxylase can fix carbon efficiently when rubisco cannot- that is, when concentration in the leaf to fall and O2 concentration to rise

Question 34

explain his changes in leaf architecture help isolate rubisco in high CO2 areas but low O2 areas

Answer 34

the mesohpyll cells of the C4 plant pump CO2 into the bundle chesty, keeping the CO2 concentration in the bundle-sheath cells high enough for rubisco to bind carbon dioxide rather than oxygen

Question 35

compare and contrast C4 plants with CAM plants. give two key similarities and two key differences

Answer 35

both thrive in hot, dry conditions and have evolved methods to reduce water loss
in C4 plants, the initial steps of carbon fixation are separated structurally from the Calvin cycle. in CAM plants, the two steps occur at different times

Question 36

explain the statement that only green cells of a plant are the autotroph while the rest of the plant is a heterotroph

Answer 36

green cells are the only auto phlox part of the plant. the rest of the plant depends on organic molecules exported from leaves via veins. in most plants, carbohydrate is transported out of the leaves in the form of sucrose, a disaccharide