The answer is D; homeostasis allows the maintenance and regulation of stability and constancy that is needed to properly function. It is found in cells, tissues and organisms,
If you have both parents with long ears and some of the offsprings have short ears, you can say both parents are heterozygous for this. Both have a dominant (long ear), and a recessive allele (short ear).
To prove this, you can draw a Punnett square, and you'll see the probabilities of the offsprings.
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Some helpful tips:
The nucleus is always going to be the big, spherical shape.
The ER is always going to be a weird, folded looking structure attached to the nucleus (rough = has ribosomes on it which are usually represented by little dots, smooth = has no ribosomes on it aka no dots)
The GA looks like the ER but it is not going to be attached to the nucleus like the ER is.
The mitochondria is always going to be pill-shaped and have weird folds inside of it.
A plant cell is rectangular, while an animal cell is circular.
From lowest to highest hierarchy it would be: planet, star, solar system, galaxy.