Using the concept that :
<span>The skin cell has twice the number of chromosomes as the sperm cell has.
</span>Hence,
<span>The sperm cell has 39 chromosomes.
The skin Cell will have = 39 x 2
                                    = 78 </span><span>chromosomes.</span>
        
                    
             
        
        
        
<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.
 
        
             
        
        
        
Answer:
Please find the explanation below
Explanation:
Virus is an organism that has been a topic of debate in biological sciences. This debate is based on whether virus should be classified as a living thing or not. However, it has been shown that viruses possess characteristics or properties of both living and non-living things. 
The living thing characteristics include;
- Ability to reproduce or replicate (in living cells only and not on their own).
The nonliving characteristics include;
- Lack of cells, which is a strong criterion for every living thing in accordance to the universal cell theory. 
- Inability to self-replicate i.e. reproduce on their own without a living host. 
 
        
             
        
        
        
Answer:
A device to measure the dimensions of a object
Explanation: