In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components<span> of </span>chromatin<span>, acting as spools around which DNA winds, and playing a role in </span>gene regulation<span>.</span>
Answer:
The genotype of the F1 was wy+/w+y.
Explanation:
One of the given options has a typo: the red eye-brown body offspring count should be 56 instead of 561.
<u>We have two genes with two alleles each:</u>
Red eyes (w+) is dominant over white eyes (w).
Brown body (y+) is dominant over yellow body (y).
The phenotypes of the F2 tesulting from a test cross (F1 x wy/wy) are:
- wy+/ey (white-eye, brown body): 670
- w+y/wy (red-eye, yellow body): 650
- wy/wy (white-eye, yellow body): 38
- w+y+/wy (red-eye, brown body 56
If the genes w and y are linked, two phenotypes in the F2 will be much more abundant than the other two. Recombination during meiosis is a rare event, so the most abundant phenotypes are the parentals (the ones present in the F1 parent).
Every individual in the offpsring has a <em>wy</em> chromosome, as this was the gamete inherited from the test cross individual.
In this case, the most abundant gametes are wy+ and w+y, so the genotype of the F1 was wy+/w+y.
Notice how when recombination occurs in the F1 parent, the recombinant gametes appear: wy and w+y+, which are the less abundant in the F2 progeny.
Answer: C
Explanation: The Moon has phases because it orbits Earth, which causes the portion we see illuminated to change. The Moon takes 27.3 days to orbit Earth, but the lunar phase cycle (from new Moon to new Moon) is 29.5 days.
the autonomic (involuntary) nervous system controls the rate at which the heartbeats. sympathetic (fight or flight) signals speed up the heart’s rate while parasympathetic (rest and digest) signals slow it down. The part or parts of the heart that forms sympathetic and parasympathetic neurons form synapses is called cardiac plexus.
Cardiac plexus is a plexus of the nerves that are present at the base of the heart and is divided into superficial and deep part. The sympathetic and the parasympathetic nerves form synapses with heart in the form of cardiac plexus.
The sympathetic nerves are responsible for activating flight or fight mode while parasympathetic nerves are responsible for restoring the normal body state.
To learn more about sympathetic nerves here
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