6: Biomagnetism (Lecture + Literature)

Question 1

Name the two ways in which lower organisms produce magnetic material

Answer 1

Magnetotactic bacteria, Iron-reducing bacteria

Question 2

What is the biomagnetic link between lower and higher organisms?

Answer 2

Both use magnetism as a form of magneto-reception

Question 3

What is magnetoreception?

Answer 3

The use of a magnetic mineral within the organism to determine direction of travel or location

Question 4

What does BOM stand for?

Answer 4

Biologically organized mineralization

Question 5

What does BIM stand for?

Answer 5

Biologically induced mineralization

Question 6

What is the primary difference between BOM and BIM?

Answer 6

BOM is intracellular, BIM is extracellular

Question 7

What are the three main mechanisms which appear to induce the creation of magnetic minerals in higher organisms?

Answer 7

Magneto-reception, Armor, Metabolic build-up – disease (?)

Question 8

Name an example of an insect that carries magnetic minerals and the reason why (Authors)?

Answer 8

Monarch Butterfly – migratory so potentially use of magneto-reception (McFadden and Jones, 1985)

Question 9

Name an example of a bird, with the type of grain (size and arrangement) carried, location of grains, reason for magnetic material, with (Authors).

Answer 9

Homing Pigeon, SP magnetite arranged in clusters on beak, used for magnetoreception (Holtkamp-Rotzler et al, 1997)

Question 10

The increase in ____ in the brain appears to be strongly linked with ____. It can be detected using a ____, commonly known as an MRI.

Answer 10

Magnetite, neurodegenerative disorders, magnetic resonance imaging.

Question 11

___ mollusks have an organ which acts as a ___ to scrape microorganisms off rocks. There are many little ___ on the ___ made from ___ crystals. The grains are used solely for their ____, not their ___ properties.

Answer 11

Chiton, tounge, teeth, radula, magnetite, hardness, magnetic

Question 12

___ is found in Limpets

Answer 12

Goethite

Question 13

What is elemental symbol of Greigite?

Answer 13

Fe3S4

Question 14

What size (μm) magnetite grains have been found on many species of fish?

Answer 14

0.03 – 0.05 μm

Question 15

In a study by (Authors) a rainbow trout was found to have ___ grains within a ___ cell on its head. It had coercivities between __ to __ mT, which is magnetically close to that of __ ___

Answer 15

Diebel et al, 2000, SD grains, magnetoreceptor, 20-40mT, bacterial magnetosomes

Question 16

What is thought to be the link between nerve tissue and magnetic minerals?

Answer 16

Magnetite in membrane allows movement of tissue through osmosis

Question 17

___ ___ are found to swim ___ and ___ in the NH and ___ and ___ in the SH. The actions in each hemisphere are due to the ___ magnetisation. It is thought that this action is used as ___ so as to keep the organism ____.

Answer 17

Magneto-tactic bacteria, northwards and downwards, southwards and downwards, opposite, magnetoreception, correct oxygen environment

Question 18

Which (Authors) studied trout heads so as to understand the presence of magnetite grains?

Answer 18

Diabel et al, 2000

Question 19

What was the location of the study by Snowball (1994)?

Answer 19

Swedish lake sediments

Question 20

What was special about the location chosen by Snowball (1994)?

Answer 20

No external input of magnetic material

Question 21

In the study by Snowball (1994), SIRM was found to be abnormally ___, at ____Am2kg-1, at a depth of ___cm.

Answer 21

High, 40Am2kg-1, 35cm

Question 22

The study by Snowball (1994) used the ____ test to confirm the presence of ____ ____.

Answer 22

Oldfield, 1994, bacterial magnetosomes

Question 23

What did Snowball (1994) find with depth, and what was the cause?

Answer 23

Decreasing fossil magnetosomes, due to dissolving by reductive diagenesis.

Question 24

What was the location used by McNeill (1990)?

Answer 24

Great Bahama Bank

Question 25

What was the test used by McNeill (1990), and what did it show?

Answer 25

Lowrie-Fuller test, positive for SD grains

Question 26

What was the secondary line of evidence used by McNeill (1990) to show presence of bacterial magnetite?

Answer 26

Microscopic observation

Question 27

What was the domain formation of the magnetite found by McNeill (1990)?

Answer 27

All SSD grains

Question 28

What was found in microscopic observation which made McNeill (1990) believe that it was BOM?

Answer 28

SD grains arranged in a chain with progressively smaller grains near the end

Question 29

Why does certain bacteria arrange itself into chains?

Answer 29

Magnetoreceptors

Question 30

How can we tell the saturation point of BOM?

Answer 30

Apply larger and larger fields while maintaining a fast rotation around the bacteria – the magnetic field at which the bacteria can no longer keep up to the spin is the point at which it is saturated.

Question 31

When are the earliest documented magneto-fossils from?

Answer 31

2.1bn a-1

Question 32

Where and when was the Martian meteorite which contained magneto-fossils found?

Answer 32

Allen Hills, Antarctica, 1984

Question 33

When did the Martian meteorite break off from Mars, and when did it make impact with Earth?

Answer 33

16mil years ago, 13,000 years ago

Question 34

What would the presence of BOM magnetite in the Martian meteorite mean for planetary research?

Answer 34

Mars has a strong magnetic field and thus liquid conducting core?

Question 35

Which (Authors) published on their magnetic findings in Swedish lake sediments?

Answer 35

Snowball (1994)

Question 36

Which (Authors) published on their magnetic findings on the Great Bahama Bank?

Answer 36

McNeill (1990)

Question 37

In Scotland, Snowball and Thompson (1988) found ___ produced by ____, (B__M). The grains acted as ___ grains, where ___ only plays a small role.

Answer 37

Greigite (Fe3S4), sulfate reducing bacteria (BIM), SD, SP.

Question 38

Snowball (1991) found a high concentration of ____ in two lakes in Sweden, with grain sizes of ___ and ___. There was no ___ grains, which means there there was likely to be no BIM component.

Answer 38

Greigite (Fe3S4), SD and PSD, no SP

Question 39

What is thought to be the possible origin of the banded iron formations, the source of ___% of iron mined today (And what geological age)?

Answer 39

Bacterial oxidation of ferrous iron, Precambrian oceans, 90%.

Question 40

Hanesch and Petersen (1999) found what when they introduced a source of “food” to BIM?

Answer 40

An increase in susceptibility caused by BIM producing magnetite

Question 41

Lovley et al (1987) found bacteria which produced a ____ which was found to be ___. Some of the grains larger than ___, as they could carry remanence

Answer 41

Black precipitate, magnetite, SP

Question 42

Who were the (authors) which added “food” to BIM to increase susceptibility?

Answer 42

Hanesch and Petersen (1999)

Question 43

Who were the (authors) whom observed a black precipitate of BIM magnetite in a river in Maryland?

Answer 43

Lovley et al (1987)

Question 44

What do you plot for the Oldfield (1994) test, and what is it thought give?

Answer 44

Xarm/X against Xarm/Xfd thought to give specific groupings of SSD biological magnetite.

Question 45

Which test do you plot Xarm/X against Xarm/Xfd to attain a grouping of SSD biological magnetite?

Answer 45

Oldfield (1994)

Question 46

What was the major scrutiny with the Oldfield (1994) test when it was first published?

Answer 46

The biological magnetite was not tested using transmission electron microscopy to be sure.