lecture 16

Question 1

What are autotrophs?

Answer 1

“self feeders” that sustain themselves without eating other organisms

Question 2

What are heterotrophs?

Answer 2

obtain organic material form other organisms

Question 3

What is photosynthesis commonly called

Answer 3

reverse respiration

Question 4

What does photosynthesis do in terms of electrons?

Answer 4

reverses the direction of electron flow compared to respiration- electrons leave water and go to carbon

Question 5

What is the function of chloroplasts in photosynthesis?

Answer 5

chloroplasts split H2O into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules and releasing oxygen as a by-product

Question 6

What kind of reactions does photosynthesis consist of?

Answer 6

light and dark reactions

Question 7

Where do light reactions occur?

Answer 7

in the thylakoids

Question 8

What happens during light reactions?

Answer 8

-split H2O
-release O2
-Reduce the electron acceptor NADP+ to NADPH
-generate ATP from ADP by photo-phosphorylation

Question 9

Where is the Calvin cycle?

Answer 9

in the stroma

Question 10

What does the Calvin cycle do?

Answer 10

forms sugar from CO2 using ATP and NADPH

Question 11

What is the site of photosynthesis in plants?

Answer 11

chloroplasts

Question 12

Where are chloroplasts located in plants?

Answer 12

In the mesophyll of leaves, the interior tissue of the leaves

Question 13

What are stomata?

Answer 13

microscopic pores on leaves where CO2 enters and O2 exits

Question 14

What is the structure of chloroplasts?

Answer 14

an envelope of two membranes surrounding a dense fluid called the stroma

Question 15

What is stroma?

Answer 15

dense fluid in chloroplasts

Question 16

What are thylakoids?

Answer 16

connected sacs in the chloroplasts that compose a third membrane system

Question 17

What are grana?

Answer 17

the third membrane system in chloroplasts

Question 18

What is chlorophyll?

Answer 18

the pigment that gives leaves their green color

Question 19

Where is chlorophyll located (specifically)?

Answer 19

thylakoid membranes

Question 20

What are photons?

Answer 20

discrete particles that make up light

Question 21

What are pigments?

Answer 21

substances that absorb visible light
Different pigments absorb different wavelengths

Question 22

What happens to wavelengths that are not absorbed?

Answer 22

they are reflected or transmitted

Question 23

What happens when a pigment absorbs light?

Answer 23

It goes from a ground state to an excited state, which is unstable

Question 24

What happens when excited electrons fall back to the ground state?

Answer 24

excess energy is released as heat

Question 25

What is fluorescence?

Answer 25

an afterglow produced by pigments that emit light in isolation

Question 26

What does the light-harvesting complex consist of?

Answer 26

pigmented molecules bound to proteins and transfer the energy of photons to the chlorophyll 'a' molecules in the reaction-center complex

Question 27

What is the reaction center complex?

Answer 27

an association of proteins holding a special pair of chlorophyll 'a' molecules and a primary electron acceptor

Question 28

Why are chlorophyll 'a' molecules so special?

Answer 28

because they can transfer an excited electron to a different molecule

Question 29

What does a primary electron acceptor do?

Answer 29

accepts excited electrons and is reduced as a result

Question 30

What is the Z scheme?

Answer 30

describes the oxidation/reduction changes during the light reactions of photosynthesis.

Question 31

What are the main products of light reactions?

Answer 31

ATP and NADPH

Question 32

What is used to fix carbon in the calvin cycle?

Answer 32

ATP and NADPH

Question 33

What are the similarities in mitochondrial and chloroplast structures?

Answer 33

-multiple membranes and compartments -both respiration and photosynthesis feature an electron transport chain -both ETC's establish a proton gradient that is coupled to ATP synthesis -generate ATP by chemiosmosis, but use different sources of energy

Question 34

What is the source of energy in mitochondria

Answer 34

H+ in intermembrane space drives ATP synthesis as H+ diffuse back into the mitochondrial matrix

Question 35

What is the source of energy in chloroplasts?

Answer 35

H+ pumped into the thylakoid space (lumen) drives ATP synthesis as H+ diffuse back into the stroma

Question 36

Where are ATP and NADPH produced

Answer 36

on the side facing the stroma where the calvin cycle takes place

Question 37

Light reactions generate ___ and ____ the potential energy of electrons by moving them from ___ to ____.

Answer 37

Light reactions generate ATP and increase the potential energy of electrons by moving them from H2O to NADPH.