Answer:
100% or 1
Explanation:
This question involves a gene coding for fur color in bears. According to the question, black fur allele (B) is dominant over the brown fur allele (b). This means that a bear heterozygous for fur color (Bb) will be phenotypically black. 
In this question, a black father bear (genotype BB) and a brown mother bear (genotype bb) were crossed, the baby bears will all have a genotype Bb (see punnet square in the attached image). Since all the offsprings of this cross have genotype Bb, this means that 100% will have black fur.
 
        
             
        
        
        
The drugs that are found are <span>Tar, </span><span>Carbon monoxide,</span><span> Nicotine and</span><span>Emphysema </span>
        
             
        
        
        
Explanation:
Cancer occurs in dividing cells only because genetic materials divide into two equal portions during division. This process may be interrupted by carcinogenes or mutagenes to make mutate cells and then render them as cancer cells. In the brain, the cells are differentiated and there is no chance to start division, then how can cancer be found in the brain.
 
        
             
        
        
        
Answer:
The correct answer is included in the Explanation section
Explanation:
An organism with considerable more chromosomes than humans: the plant <em>Ophioglossum reticulatum</em> with 1260 chromosomes.
An organism with considerable fewer chromosomes than humans: the ant <em>Myrmecia pilosula</em> with 1 chromosome.
It might be thought that the chromosome number of a species is directly related to its complexity, meaning that an organism with a large number of chromosomes is more complex than an organism with a small number. However, this is not true. Chromosomes are structures of coiled DNA, and its number indicate how the cells wrapp their genomic material when they reproduce. The number of chromosomes is not related to the organism complexity, but rather the number of genes and their function.
 
        
             
        
        
        
The surface area to the volume ratio gets smaller as the cell gets larger. If the cell grows beyond a certain limit not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. 
Hope that helps