They are called even-aged
hope this helped :)
Answer: True
Cell -> Tissue -> Organ -> Organ System -> Organism.
Answer:
To think in picture is like visual thinking. When you are thinking in pictures you are have a visual image but instead of having it in front of you, it is. more like thinking about it inside you head. An example would be when people think of things like let's say dogs. Most people will think in pictures of an dog inside their mind. They will visualize how a dog would run around, and play fetch, etc.
The most likely explanation for the variation is the offspring were produced from different combination of genes. A single pair of gold fish mentioned in the question means a male and a female gold fish. The two of them mated and contributed different genes to the fertilized fish eggs, this results in production of various body shape and colouration which is known as variation.