Exam 1 - January 2017

Question 1

What is life? - historical ideas

Answer 1

In the classical period:
Democritus - life is anything that contains a soul (psyche)
Elements explained everything
Aristotle - life is matter and form (psyche)
18th/ 19th century:
George Stahl - vital-ism - there are two kinds of matter (organic and inorganic)
Now:
Life forms are described as Biota (they show metabolism, homeostasis, they grow, respond and multiply)
Non living: dead or innate

Question 2

Ingredients for life?

Answer 2

Chemically:
Carbon, oxygen and hydrogen
Major nutrients (nitrate and phosphate)
Micro nutrients
Energy:
Solar radiation from sun

Question 3

The Early Earth evolved as meteor showers, volcanic eruptions and lighting (electrical energy) provided energy.
This is show in the Miller - Urey Experiment 1952

Answer 3

Simulated early Earth in laboratory flask:

Primordial Ocean generating water vapour and lighting to power –> they fed into the primordial atmosphere (Deuterium, Nitrogen, Ammonia, Water, Methane, Carbon Dioxide)

This reaction of basic material triggered intermediate (simple carbon compounds) and final products (amino acids) - the building blocks for proteins

Question 4

Amino acids make up

Answer 4

Proteins
Enzymes are a key proteins that allow molecules to slot into them and create new products (eg larger molecules)
They are biological catalysts, helping photosynthesis, protein synthesis and aerobic respiration.

Question 5

Life needs chemicals, and there is specific ratio or recipe for them

Answer 5

Carbon, nitrogen and oxygen are needed

The Redfield ratio (which is most effective in marine species) is

106:16:1

Carbon: nitrogen: phosphorous

Question 6

There are 4 essential molecules types of living things are?

Answer 6

Proteins (made from chain of amino acids)

Carbohydrates (carbon, hydrogen and oxygen)

Nuclei acids (DNA and RNA)

Lipids (Lipids are large molecules made from smaller units of fatty acids and glycerol)

Question 7

Amino Acids.
How many are there?
What is the most basic one?
How do amino acids form?

Answer 7

There are 21 amino acids

Alanine is the most basic one, made by life forms.

In a chain attached to each other:
2 = di-peptides
2< = polypeptides (proteins) - build cellular structures

The chain is always different and will react

Question 8

Proteins are a key building block of life, they are in every cell in the human body.

They make up..

and an example of this is…

Answer 8

Proteins make up biomolecules (involved in the maintenance and metabolic processes of living organisms)

One example of this is an enzyme, they have a specific combination of amino acids (3D structure) to function chemically

Question 9

DNA is an important building block for life

Answer 9

A section of DNA that has the genetic code for making a particular protein is called a gene.

The bases (ATGC) code for particular chains of amino acids

DNA is made up of molecules and proteins

Question 10

So key part of living organisms is metabolism:
What is it?
Metabolism has two functions…
The key function is the capture of energy, and there are also two ways to do this…

Answer 10

Metabolism - is a term that is used to describe all chemical reactions involved in maintaining the living state of the cells and the organism.

Catabolism - the breakdown of molecules to obtain energy
Anabolism - the synthesis of all compounds needed by the cells

This is further divided :
Autographs are organisms that can capture energy from the sun light and chemicals (inorganic)
Heterographs are organisms that gain energy from other organisms (organic)

Question 11

Evidence for life in the early earth comes from…

Answer 11

Cyanobacteria (blue-green algae)

They are up to 3.5 million years old, but are still around today in Shark Bay, Australia, where they have built stromatolites

They have the ability to capture energy from the sun and perform photosynthesis.

Question 12

After cyanobateria, produced oxygen through photosynthesis green plants evolved and were able to carry on this process

Answer 12

CO2 + 6H2O + Light –> C6H12O6 + 6O2

Carbon Dioxide + Water + Light –> Glucose + Oxygen

Question 13

How did we get from the Early atmosphere to today’s atmosphere?

Answer 13

Autotrophs (producer):

1. Photoautotrophs - photosynthesis
2. Chemoautotrophs -
   chemosynthesis (usually converting methane into organic carbon)

Heterotrophs (consumer):

1. Photoherotrophs: depend on light for their source of energy and mostly organic compounds from the environment for their source of carbon
2. Chemoheterotrophs - unable to utilize carbon dioxide to form their own organic compounds. Their carbon source is rather derived from sulfur, carbohydrates, lipids, and proteins.

Question 14

How may life exist outside Earth?

Extremophiles…

Answer 14

1. Thermophiles (hot enviroments - hot spots)
2. Hyperthermophiles (extremely hot enviroments - deep ocean hydrothermal vents)
3. Alkaphile (extreme pH - soda lakes - Natron pH 10)
4. Psychophile (live on ice - Bloof falls Antartica)

Question 15

Biochemistry:
Organism have and active role in the chemical composition of the earth…

They store energy in chemical batteries:

Answer 15

They take up carbon dioxide when they grow in spring - see variation

ATP - organic molecule

ADP created when remove phosphorous to creat energy

Question 16

Important molecules to plants for strength:

Answer 16

Cellulous - gives strength to cell wall (abundant)

Lignin - additional support