bio chap 8 Flashcards
Recall that cyanobacteria may have developed as a result of horizontal gene transfer: a bacterium carrying the genetic information for one photosystem received (from another bacterium) the genetic information for a second, distinct photosystem. What might be possible mechanisms of action for horizontal gene transfer?
Bacteria could take up genetic information (released from dead bacteria) from their surroundings.
****Bacteria may exchange genetic information through the development of cytoplasmic connections.
** Bacteria may become infected by a virus that carries genetic information taken from previously infected bacteria.
$$$all options are correct
Which of the following statements is true regarding the earliest photosynthetic organisms on earth
The organisms likely used inorganic molecules (H2S) as electron donors
The Z scheme refers to
the energy inputs associated with electron transport
The regeneration of RuBP typically limits the rate of photosynthesis under low light intensities. This is because
RuBP regeneration requires ATP…
All photosynthetically competent cells contain
a plasma membrane
Organisms with only one photosystem cannot
produce O2
Chemicals called un-couplers can make membranes permeable to small molecules and ions. What affect might un-couplers have on photosynthesis
Decreased ATP production because the proton-gradient would decrease
The evolution of photosynthesis involved…
horizontal gene transfer and endosymbiosis
How many mol NADH are required for 12 mol RuBP to be carboxylated by rubisco
not 10,12,24,36
Which of the following is at the highest energy level
(1) blue light
(2) green light
(3) red light
blue light
CO2 reduction requires
ATP and NADPH
For every 6 CO2 molecules fixed, how many triose phosphates are exported from the chloroplast
2
In plants and algae, which of the following is a by-product of photosynthesis
O2
Which of the following statements is true regarding the Calvin Cycle? (4 false things)
The calvin cycle is considered a “dark” rx, because it is not directly related to photosynthesis
- *the calvin cycle is a carefully regulated process because excess starch can be toxic to plant cells
- **the calvin cycle uses a rare (and this “rate-limiting”)enzyme called rubisco
- **the calvin cycle produces high energy triose phosphate only through the action of rubisco
During photosynthesis in plants and algae, is oxidized and is reduced
H20 ; CO2
PS II and PS I differ in….
H+ production, and electron donors and acceptors
During their experiments with chlorella, Calvin and Benson found no free glucose. Why do you think this is?
**glucose is stored as starch
Eukaryotes conduct all of the photosynthesis that occurs in the ocean. TRUE/FALSE
FALSE
Prokaryotes account for roughly half of terrestrial photosynthesis
FALSE
In plants and algae, is the source of the electrons needed for photosynthesis
H20
PS I is a than PSII
weaker oxidant and a stronger reductant
cyclic electron transport enhances ATP production because….
electrons are transferred from ferradoxin to plastoquinone
Assuming that all is working properly, which of the following is at a higher energy level
an excited-state antennae chlorophyll
From its ground state, PS II can
absorb light energy
In addition to chlorophylls, light-harvesting antennae include other pigments. What is the benefit of these additional pigments?
Narrower range of wavelength reflection
Many photosynthetic prokaryotes are capable of cyclic electron transport only. It is likely that such organisms can but not .
Produce ATP, reduce CO2
How does the metabolism occuring in chloroplast differ from that of mitochondria
*different electron acceptors and sources
Antennae accompany rx centers promoting
energy transfer
collectively, most photosynthesis carried out in the ocean is performed by prokaryotes and not eukaryotes
FALSE
A researcher is carrying out an experiment where she labels a protein with a fluorescent tag (so she can visualize its location in a cell), and introduces this tagged protein into the lumen of a single thylakoid. She observes her treated cells periodically, and notices that the labeled protein can move between grana, but it never observed in the stroma. What can she deduce
the protein likely travels through a common lumen shared by thylakoid membranes and grana, and cannot easily diffuse through the thylakoid membrane
The calvin cycle and light-harvesting reactions are separated in…
space
All photosynthetically competent cells contain ____________.
a plasma membrane
During photorespiration, the phosphoglycolate (PGO) produced by RuBP oxygenation is eventually converted to PGA; 75% of the carbon in PGO is recovered. How many molecules of PGO are required to generate two molecules of PGA through this route?
four
In the lab you isolate a Chlorella mutant that is unable to switch xanthophyll pigments into the inactive, non–heat-dissipating form. If you released that mutant into a small pond shaded by trees, would the mutation spread, and why
No, light absorbed by xanthophylls is not used to make ATP or NADPH
Assuming that all is working properly, which of the following is at a higher energy level?
An excited-state antenna chlorophyll
Antennae accompany reaction centers, promoting ____________.
electron transfer
For every six CO2 molecules fixed, how many triose phosphates are exported from the chloroplast?
2
In the Calvin cycle, ATP is required to ____________
phosphorylate 3-PGA
In plants and algae, which of the following is a by-product of photosynthesis?
O2
NADPH production requires ____________.
light and electrons
Many photosynthetic prokaryotes are capable of cyclic electron transport only. It is likely that such organisms can ____________ but not ____________.
produce ATP; reduce CO2
Over evolutionary time, photosynthesis has effectively poisoned itself by producing an oxygenic atmosphere because ____________.
rubisco is an oxygenase and O2 is a strong oxidant
Electrons move between PSII and PSI via ____________.
cytochrome b6f
Low temperatures slow the activity of rubisco but enhance its ability to select CO2 over O2. Low temperatures thus ____________.
increase the production of reactive oxygen species
True or false: The products of the Calvin cycle are 3-carbon sugars
true
Which of the following is needed directly to produce both triose phosphates and RuBP?
ATP
CO2 reduction requires ____________
ATP and NADPH
ATP production requires ____________.
light, electrons, and protons
True or false: Eukaryotes conduct all of the photosynthesis that occurs in the ocean
false
Which of the following compounds is consumed by carboxylation?
RuBP
The occurrence of photorespiration ____________ CO2 and ____________ ATP.
produces; consumes
The evolution of photosynthesis involved ____________.
horizontal gene transfer and endosymbiosis
The Calvin cycle includes 15 enzymes, most of which are involved in ____________.
RuBP regeneration
Over evolutionary time, photosynthesis has effectively poisoned itself by producing an oxygenic atmosphere because ____________.
rubisco is an oxygenase and O2 is a strong oxidant
The regeneration of RuBP typically limits the rate of photosynthesis under low light intensities. This is because ____________.
RuBP regeneration requires ATP
