What is the best description of the word 'recessive' as it is used in biology? A. Having two identical versions of an allele in a cell.
B. An allele that is always expressed, even if there is only one copy in a cell.
C. An allele that induces reclusive behavior in an organism.
D. An allele that is only expressed if two versions of it are present in a cell.
boil

An allele that is only expressed if two versions of it are present in a cell.

boil

answer: andy garner, a 17-year-old who decided to become a human guinea pig in 1965 and go without sleep for 11 days. by the second day his eyes had already stopped focusing, and he lost the ability to identify objects by touch. by day three he was moody and uncoordinated and by the end he had trouble with short term memory and had even started hallucinating.

and a rare genetic mutation called fatal familial insomnia, where people can’t sleep at all, gets progressively worse over months or years and leads to dementia and death.

a devoted soccer fan died after staying awake 48 hours to watch the world cup, she said. ‘while his untimely death was due to a stroke, studies show chronically sleeping fewer than six hours a night increases stroke risk by 4 1/2 times compared with those getting a consistent seven to eight hours.'

*shorten it up as your wish*

(i have divided it into 3 simple paragraphs)

the right option is; decreased genetic variation  

decreased genetic variation describes the effect of this environmental change.

genetic variation is the naturally occurring genetic diversities or differences between organisms of the same species in a population. genetic variation allows the survival and adaptability of a species when they encounter changing environmental conditions. when an endangered species reduces, it loses genetic variation which may not be restored even if the species rebound and will only be recovered through the gradual collection of mutations over many years.