Answer:
its like any other disease
Explanation:
was there more to the question?
They start as single cell orginisms then they evolve from there.
hope that helps
Answer:
The presence of an additional chromosome
Explanation:
Look at "pair" 21. See how there are THREE chromosomes instead of TWO? Normally, there would only be two chromosomes in each pair but this karyotype shows a trisomy (see def. below) of the 21st pair. This was caused by a nondisjunction mutation of the 21st pair. The is also the karyotype of a person with Down's Syndrome.
Definition of Trisomy:
A condition of the presence of three chromosomes in a pair instead of two. This normally causes developmental irregularity.
Answer:
See the answer below
Explanation:
<em>Genotype is the genetic composition of organisms and a gene is made up of two alleles.</em>
a) Since the allele for black is B, <u>the genotype for black chickens would be BB. </u>
b) Since the allele for white is W, <u>the genotype for white chickens would be WW.</u>
c) Since erminette color is heterozygous,<u> the genotype would be BW.</u>
d) Two erminette were crossed:
BW x BW
BB BW BW WW
i. <em>Probability of having black chick (BB) </em>= 1/4
ii. <em>Probability of having a white chick (WW)</em> = 1/4
iii. <em>Probability of having erminette chicken (BW)</em> = 1/2
Answer: depolarization; hyperpolarization
Explanation:
At resting potential (absence of stimulus), the cell membrane of a neuron is said to be polarized with a net negative charge within due to more potassium (K+) ions present than sodium (Na+) ions.
However, an impressed stimuli reverses the ions content as K+ ions flows out and quickly replaced by Na+ ions, resulting in a decrease in membrane potential and a more positive cell membrane. Thus, depolarization occurs.
An increase in the membrane potential (so that it becomes more negative) is called hyperpolarization.
