Evidence for the origin of life

Question 1

Conditions on early Earth

Answer 1

Massive oceans existed

Only small landmasses above the surface of the water

No ozone layer

Large amounts of radiation reached the Earth

No free oxygen in the air (anoxic environment)

Large amounts of volcanic activity; heat, ash, dust and gases into atmosphere

Violent electric storms common

ammonia, water vapour, hydrogen and methane

Question 2

Gases in the atmosphere

Answer 2

methane

water vapour

hydrogen

ammonia

Question 3

main organic molecules

Answer 3

water

carbohydrates

lipids

proteins

nucleic acids

Question 4

the basic organic compounds, water, carbohydrates, lipids, proteins, and nucleic acids, are made up of what?

Answer 4

hydrogen (H), oxygen (O), carbon (C), nitrogen (N) and some other common elements

Question 5

what provided energy for molecules to be formed

Answer 5

The lack of an ozone layer, the frequent violent electric storms, and the volcanic activity of early Earth

Question 6

was early Earth oxic or anoxic

Answer 6

anoxic

Question 7

simple organic molecules contain which elements

Answer 7

carbon
hydrogen
oxygen
nitrogen
smaller amounts of phosphorous and sulfur

Question 8

simple organic molecules are known as the building blocks of life and consist of what?

Answer 8

amino acids

nucleic acid bases

sugars and

phosphoric acid

Question 9

why are amino acids called the building block of life

Answer 9

because they combine in different arrangements to form different types of proteins

Proteins in turn are responsible for the formation, repair and function of all cells in living organisms

Question 10

how many types of amino acids are there

Answer 10

20

Question 11

what is a reducing atmosphere

Answer 11

an atmospheric condition in which oxidation is prevented by removal of oxygen and other oxidizing gases or vapours, and which may contain actively reducing gases such as hydrogen, carbon monoxide and gases, such as hydrogen sulfide, that would be oxidized by any present oxygen

Question 12

what is ‘primordial soup’

Answer 12

a term coined by biologist Alexander Oparin

the early conditions on earth that had an atmosphere which allowed life to begin

Question 13

name two theories on the origin of life

Answer 13

There are two possible sources for organic molecules.

They can be:

made on the Earth from simpler molecules (theory of BIOCHEMICAL EVOLUTION) OR (chemosynthetic theory)

arrive from space on meteorites. (theory of PANSPERMIA)

Question 14

what is the theory of panspermia

Answer 14

the belief that meteorites brought living organisms from space which were then able to initiate life on reaching a suitable environment

Question 15

evidence of panspermia

Answer 15

Murchinson meteorite (1969) in Victoria Australia, which contained amino acids

Question 16

what is the theory of biochemical evolution (chemosynthetic theory)

Answer 16

the chemical evolution of cellular life

all the elements were available in the atmosphere and with energy they rearranged into organic molecules

Question 17

evidence of biochemical evolution (chemosynthetic theory)

Answer 17

Urey and Miller

proved that reactions in a reducing atmosphere could lead to the formation of organic molecules through various experiments (amino acids)

Question 18

main 4 gases present in early earth

Answer 18

hydrogen

methane

ammonia

water vapour

Question 19

energy sources on early earth

Answer 19

volcanic activity

lightning

radioactivity from the sun

Question 20

what did Urey and Miller do

Answer 20

sealed a mixture of water, ammonia, methane and hydrogen in a sterile flask

the mixture was heated to evaporate water to produce water vapour

electric sparks were passed through the mixture of water vapour and gases, simulating lightning

after a week, contents were analysed

amino acids, the building blocks for proteins, were found

Question 21

what did the Urey and Miller experiment proves

Answer 21

the theory of a ‘primordial soup’, the idea that complex chemicals needed for living things to develop could be produced naturally on the early Earth

if early Earth did contain those chemicals, life could
have formed from inorganic molecules.

(biochemical evolution)

Question 22

what changes in technology have allowed us to accurately date fossils and identify chemicals and molecular structure this gave evidence to support the action of organic compounds

Answer 22

electron microscopes

spacecraft

deep sea exploration vessels

carbon dating

Question 23

how have electron microscopes advanced technology and help scientists in identifying fossils

Answer 23

has meant that microfossils within rocks can now be seen

this has extended the evidence of live on Earth and also may identify fossils from other planets

Question 24

how have spacecraft advanced technology and help scientists in identifying fossils

Answer 24

sending spacecraft to other planets makes it possible to examine conditions on these planets to compare to the conditions on early Earth

Question 25

how have deep sea exploration vessels advanced technology and help scientists in identifying fossils

Answer 25

the presence of deep-sea vents was unknown until vessels were developed that could travel to the depths of the oceans

once this occurred it was discovered that there were many unknown organisms living on the vents and using the energy from the vents as a basis for an ecosystem

Question 26

Identify changes in technology that have assisted in the development of an increased understanding of the origin of life and evolution of living things:

Answer 26

The Urey/Miller experiment has been improved using modern technology

electron microscope - enabled discovery of microorganisms , can see to protein level

DNA hybridisation - by comparing their DNA sequences and seeing what percentage they are similar, the higher the closer related

Question 27

Reason for the Urey and Miller experiment

Answer 27

To test the hypothesis of Haldane and Oparin

i.e. organic molecules could have been created on the surface of early
Earth, from inorganic molecules using energy from UV rays and lightning