Chloroplasts and Photosynthetic Pigments

Question 1

name the components of the chloroplast

Answer 1

outer membrane, inner membrane, inter-membrane space, lamellae, grana, thylakoid, stroma and DNA.

Question 2

how big is a chloroplast?

Answer 2

2-10 um long
inter membrane space is 10-20 nm

Question 3

describe the membranes of the chloroplast

Answer 3

Each of the envelope membranes is a phospholipid bilayer
The outer membrane is permeable to a range of ions and small molecules
The inner membrane contains transport proteins that only allow certain molecules or ions to enter or leave the chloroplast

Question 4

what is the stroma?

Answer 4

cytosol-like fluid
contains enzymes, starch grains,CO2, sugars, oil droplets, 70s ribosomes and DNA

Question 5

what is the function of DNA in the stroma?

Answer 5

contains genes that code for some of the proteins needed for photosynthesis and the proteins are assembled at the chloroplast ribosomes

Question 6

what is the grana?

Answer 6

stacks of thylakoid membranes some of the thylakoids may be connected with thylakoids in a different granum by intergranal lamellae

Question 7

Describe two ways in which grana is adapted to its function

Answer 7

contain, (named) pigment (molecules) / photosystems;
contain, (named) electron carriers / ETC / ATP synth(et)ase;
idea that has a large surface area (in a small volume) for, light absorption / light dependent reaction(s) / light dependent stage / electron transport

Question 8

how do the photosystems stay in place?

Answer 8

by proteins embedded in the thylakoid membranes

Question 9

how are the photosynthetic pigments arranged in the thylakoid membranes?

Answer 9

light-harvesting clusters known as photosystems

Question 10

what shape is the photosystem?

Answer 10

funnel-shaped

Question 11

where is chlorophyll a in the photosystem?

Answer 11

the primary pigment reaction centre

Question 12

what is the primary photosynthetic pigment?

Answer 12

Chlorophyll a

Question 13

what are the two different types of chlorophyll a and where are they found?

Answer 13

P680 which has a peak absorption at wavelength of 680nm and found in photosystem II
P700 which has a peak absorption at wavelength of 700nm and found in photosystem I

Question 14

what colour does chlorophyll a absorb?

Answer 14

both absorb red light but reflect green light so plants appear green
some chlorophyll a absorbs some blue light at 440nm

Question 15

what is the structure of chlorophyll a?

Answer 15

a porphyrin group which contains a magnesium atom and a long hydrocarbon atom

Question 16

State the advantage to the plant of having a range of accessory pigments in photosystems.

Answer 16

they are able to absorb a range of different light wavelengths

Question 17

How does the pigments work together?

Answer 17

energy associated with the wavelengths of light captured is funnelled down to the primary pigment reaction centre

Question 18

name the accessory pigments?

Answer 18

Chlorophyll b, carotenoids and xanthophyll

Question 19

What does chlorophyll b absorb?

Answer 19

absorbs light of wavelengths 400-500nm and around 640nm
absorbs blue/green and reflects yellow green

Question 20

what does carotenoids absorb?

Answer 20

absorbs wavelength of 400-500nm
absorbs blue light and reflects yellow/orange

Question 21

what does xanthophyll absorb?

Answer 21

absorbs wavelengths of 375-550 nm
absorbs blue and green light
reflects yellow light

Question 22

how do you separate the pigments in chlorophyll?

Answer 22

thin layer chromatography

Question 23

how would you carry out the thin layer chromatography?

Answer 23

mash a green leaf
spot chlorophyll onto a TLC sheet
solvent should move up separating the pigments
calculate pigments Rf values