<u>Answer</u>: The answers are matched as follows:
African forests have been hunted to near extinction levels to obtain ivory-------------->human exploitation
The eruption of mount Saint Helens destroyed some populations of conifers------> natural disasters
An infection with a fungus reduced the population of North American Elm trees ----> disease
Increasing global temperatures have altered migration patterns of humpback whales ------>climate change
<u>Explanation</u>:
<em>Human</em> <em>exploitation</em> is the unethical or selfish use of resources to satisfy their own personal needs or for any profitable activity which harms the resources in such a way that they get limited. Humans have been hunting elephants to obtain ivory for many purposes such as making jewellery etc. and earning profits from it. Due to such extensive hunting they have driven the elephants to a level of extinction and thus, this is a form of human exploitation.
Mount Saint Helens is a volcano and its eruption which harms the population of the trees in the area is a form of natural disaster since volcanic eruption is a <em>natural</em> <em>phenomena</em>.
Fungal infection is a <em>disease</em> which is cause by the microorganisms which harms the population of the Elm trees.
Increase of global temperature is a type of climate <em>change</em> and thus, this effect of alteration of migration pattern is caused by climate change.
The Doppler Effect is also known as red shift. Red shift shows the distance of galaxies. The redder the shift then the further away the galaxy, however the bluer the galaxy then the closer it is. Red Shift shows that the universe is continuously expanding. <span />
Catabolite repression is characteristic for prokaryotic organisms such as bacteria and this is the way to control metabolism.
It is called repression, because enzymes that are involved in other sugar's metabolism are inhibited (repressed). The system of catabolite repression have components such as:
sensory systems-detects ratios of glycolytic intermediates,
global regulators-control the expression of genes that encode for enzymes.