Lecture 9b: Bioenergetics- photosynthesis

Question 1

Autotrophs

Answer 1

are able to carry out carbon fixation using CO2 as a carbon source; also called primary producer

Question 2

organisms obtain carbon in one of 2 ways;

Answer 2

Autotrophs and heterotrophs

Question 3

Heterotrophs

Answer 3

organisms are unable to synthesize its own organic carbon-based compounds and as a result, they feed on organic matter

Question 4

organisms obtain energy in one of 2 ways;

Answer 4

phototrophs and chemotrophs

Question 5

phototrophs

Answer 5

are photosynthetic organisms that use light as their energy source

Question 6

Chemotrophs

Answer 6

are organisms that obtain energy by the oxidation of reduced compounds (electron donors) in their environments

Question 7

photoautotrophs

Answer 7

plants, algae, and cyanobacteria

Question 8

photosynthesis

Answer 8

the process by which all photoautotrophs use light energy to make sugars and other organic food molecules from CO2 and water (creates biomass and oxygen)

Question 9

Light reactions

Answer 9

the light driven production of ATP (phosphorylation) and NADPH

Question 10

Carbon fixation

Answer 10

the conversion of CO2 to carbohydrates

Question 11

Chloroplast

Answer 11

An organelle found in plants and photosynthetic protists absorbs sunlight and uses it to power the synthesis of organic food molecules (sugar)

Question 12

Structure of chloroplast:

Answer 12

• out and inner membranes
• Stroma
• thylakoid (Granum)
  - thylakoid membrane
  - thylakoid lumen

Question 13

Photosynthetic pigments:

Answer 13

• Chlorophyll a
• Chlorophyll b
• Carotenoids

Question 14

Chlorophyll a

Answer 14

absorbs light within the violet, blue and red wavelengths while mainly reflecting green

Question 15

Chlorophyll b

Answer 15

extends the absorption spectrum and acts as an accessory pigment that also participates in light absorption

Question 16

carotenoids

Answer 16

another accessory pigment that absorb different wavelengths of light

Question 17

Photosystem

Answer 17

a light-harvesting unit of a chloroplast thylakoid membrane, containing a reaction center plus antenna complexes (2 types)

Question 18

2 types of photosystems

Answer 18

photosystem I + photosystem II

Question 19

Photosystem I

Answer 19

(PS I), also called P700 because the reaction center associated with PS I has an absorption peak at 700nm (red light)

Question 20

photosystem II

Answer 20

(PS II), called P680 made up of a reaction center with an absorption peak of about 680 nm (orange shade of red)

Question 21

Noncyclic electron flow

Answer 21

involves both Photosystems I & II and produces ATP and NADPH

Question 22

Cyclic electron flow

Answer 22

uses only photosystem I and produces only ATP
- no h20 splitting occurs
- ATP is formed by chemiosmosis

Question 23

Carbon Fixation

Answer 23

Step 1- carbon fixation
Step 2- Energy consumption and carbon reduction
Step 3- RuBP regeneration