Understanding present and past organisms

Question 1

Describe technological advances that have increased our knowledge of procaryotic organisms:

Answer 1

DNA hybridisation (percentage of similarity)

Electron microscope (can see to protein level, discovered microorganisms, fine detail)

Question 2

where is archaebacteria found

Answer 2

Hostile environments such as salty brines (halophiles), boiling springs, ocean thermal vents.

Question 3

role of archaebacteria in ecosystem

Answer 3

carry out inorganic reactions for chemical energy

Question 4

where is eubacteria found

Answer 4

Are widespread including all habitats:

Land, freshwater, marine and in a host. Well known for the diseases many of them cause

Question 5

role of eubacteria in ecosystem

Answer 5

ingle-celled organisms that are parasitic or decomposers.

They play an essential role in recycling in ecosystems.

Question 6

where is cyanobacteria found

Answer 6

Widespread, especially in marine environments.

ancient forms exist in stromatolites.

Some are free- living and some exist in mutualistic association with fungi in lichens.

Question 7

role of cyanobacteria in ecosystem

Answer 7

Photosynthetic, therefore produce oxygen, use carbon dioxide and are the basis of food webs.

Many have nitrogen fixing abilities and so enrich soil where they live.

They are key components in plankton

Question 8

where is nitrogen-fixing bacteria found

Answer 8

Occur in nodules living mutualistically on the roots of legume (pea) plants.

They are also associated with other plants including cycads and water ferns.

Some types are found free living in the soil.

Question 9

role of nitrogen-fixing bacteria in ecosystem

Answer 9

Convert nitrogen from the atmosphere into ammonium ions that can be converted in amino acids in plants

Enables plants to grow in low-nitrogen soils.

In the long-term they enrich soils with nitrogen

Question 10

where are methanogens found

Answer 10

Anaerobic conditions such as the sediment at the bottom of lakes and ponds, sewerage lagoons and in the intestinal tracts of animals.

Question 11

role of methanogens bacteria in ecosystem

Answer 11

Uses hydrogen, or hydrogen- rich compounds and carbon- dioxide to produce energy and release methane as waste

Question 12

where are deep-sea bacteria found

Answer 12

The boiling undersea vents of volcanoes that are underwater

Question 13

role of deep-sea bacteria in ecosystem

Answer 13

They are the basis of food webs in undersea vents, making use of sulfur compounds from volcanoes for energy.

Question 14

Cyanobacteria in the past

Answer 14

among the most abundant fossils in PRECAMBRIAN ROCKS (3.5 billion years old).

Some scientists think they were the only organisms present at this time.

In Precambrian times:
- There was more UV radiation than today

• There was no free oxygen until the first cyanobacteria developed primitive photosynthesis

+ Stromatolites (made of cyanobacteria) were more common than today and also wider spread.

+ Cyanobacteria; some were free-living

+ Stromatolites were found in the layered rocks

Question 15

Cyanobacteria in the present

Answer 15

+ Cyanobacteria are still common today:

• Damp areas, ponds, streams
• No longer the only life form

+ Today, most are aquatic forms, some are free-living in the soil

• Some are marine stromatolites
• Some live in a mutualistic
  relationship with fungi (lichens)

+ Today stromatolites are found at Shark Bay, WA; Sea water there is really salty

+ They occur in those environments close
to limestone and low in nutrients

+ Stromatolites are now in danger of extinction due to rising nutrient levels due to fertilisation. Rise in competition

+ This possibly happened in Precambrian times

Question 16

Explain the need for scientists to classify organisms:

Answer 16

It enables organisms to be DESCRIBED quickly and accurately

􏰀 It makes COMMUNICATION simpler and more precise

􏰀 It lets newly IDENTIFIED organisms belong to particular groups

􏰀 It enables TRENDS in groups to be observed

􏰀 It helps to identify relationships and establish EVOLUTIONARY pathways

Question 17

how to remember order of classification

Answer 17

king
peter
cried
out
for
good
soup

Question 18

Discuss, using examples, the impact of changes in technology on the development and revision of biological classification systems:

Answer 18

• When organisms were classified just according to their external structure
  (Linnaeus’ system) there were only 2 kingdoms: plants and animals

- The invention of the light and electron microscopes, and the discovery of cells and the discovery of micro-organisms increased the number of kingdoms to 5

• Advances in molecular biology and biochemistry revealed the two major groups within the procaryotic monera: the Archaeobacteria and the Eubacteria.
• Hence the number of kingdoms has increased to 6
• The advances in molecular techniques, like DNA and amino acid sequencing have
  revealed new relationships between organisms
• All these advances in technology have allowed taxonomists to continually change and refine the current classification systems.

Question 19

Identify and discuss the difficulties experienced in classifying extinct organisms:

Answer 19

• We only know of many extinct animals from their fossils
• Fossils can be difficult to classify because they are often incomplete or may not
  show enough detail of the organism
• If the organism has been extinct for a very long time, there may be no other
  organisms to classify it with
• Fossils can be named even if they only have a part of the fossil
• If the same organism is given 2 or more scientific names due to incomplete fossils,
  the first name given is taken as the correct one.

Question 20

Explain how classification of organisms can assist in developing an understanding of present and past life on Earth:

Answer 20

• Ordering: Grouping organisms together brings a sense of order to a vast range of organisms. Classification also simplifies the description of things
• Communicating: All scientists throughout the world use the same names no matter what language they speak; this means there is no confusion
• Relationships: Show relationships with other organisms present today. Some show evolutionary pathways (phylogenetic)
• Conservation: Through classification and observing organisms in different
  environments, we can learn about endangered species and try to save them from extinction in the future.