8.1 Photosynthesis: An Overview

Question 1

photosynthesis is the major entry point for energy into biological systems because it is the source of:

Answer 1

all the food we eat (plants and indirect consumption of meats), oxygen, fuels for heat and transportation

Question 2

where does photosynthesis take place?

Answer 2

everywhere as long as sunlight is available (both eukaryotes and prokaryotes)

Question 3

photic zone

Answer 3

the surface layer of the ocean through which enough sunlight penetrates to enable photosynthesis

Question 4

carbohydrates are synthesized from CO2 but have more chemical energy in their bonds than CO2, so to build carbohydrates from CO2 requires:

Answer 4

an input of energy (sunlight)

Question 5

how does energy from sunlight become incorporated into chemical bonds?

Answer 5

the synthesis of carbohydrates from CO2 and water is a reduction-oxidation or redox reaction

Question 6

reduction

Answer 6

a reaction in which a molecule gains electrons (and gains energy)

Question 7

oxidation

Answer 7

describes a reaction in which a molecule loses electrons (and releases energy)

Question 8

electron donor

Answer 8

a molecule that loses electrons

Question 9

in photosynthesis, energy from sunlight is used to produce:

Answer 9

ATP and electron donor molecules capable of reducing CO2 (inputs energy to form carbohydrates)

Question 10

where do the electrons used to reduce CO2 come from?

Answer 10

the oxidation of water (an electron donor) results in the production of electrons, protons and O2

Question 11

the oxidation of water is linked with:

Answer 11

the reduction of CO2 through a series of redox reactions in which electrons are passed from one compound to another

Question 12

photosynthetic electron transport chain

Answer 12

a series of redox reactions in which light energy absorbed by chlorophyll is used to power the movement of electrons; in oxygenic photosynthesis, the electrons ultimately come from water and the terminal electron acceptor is NADP+

Question 13

the absorbed sunlight provides the energy that:

Answer 13

drives electrons through the photosynthetic electron transport chain

Question 14

movement of electrons through the photosynthetic electron transport chain is used to produce:

Answer 14

ATP and NADPH (which provides the energy needed to synthesize carbohydrates in the Calvin cycle)

Question 15

Calvin cycle

Answer 15

the process in which carbon dioxide is reduced to synthesize carbohydrates, with ATP and NADPH as the energy sources

Question 16

in photosynthetic bacteria, the photosynthetic electron transport chain is located:

Answer 16

on the plasma membrane

Question 17

thylakoid membrane (in eukaryotes)

Answer 17

a highly folded membrane in the centre of the chloroplast that contains light-collecting pigments and that is the site of the photosynthetic electron transport chain

Question 18

grana (singular: granum)

Answer 18

interlinked structures that form the thylakoid membrane, they look like stacked pancakes

Question 19

lumen

Answer 19

in eukaryotes, the continuous interior of the endoplasmic reticulum; in plants, a fluid-filled compartment enclosed by the thylakoid membrane; generally, the interior of any tubelike structure

Question 20

stroma

Answer 20

the region surrounding the thylakoid, where carbohydrate synthesis takes place