Answer:
1. Adenine
2. Thymine
Explanation:
These are the four nitrogen bases of DNA nucleotides. It's just something that you have to memorize in order to be able to successfully study DNA. In case you are asked which base pairs with which, always remember this saying about base pairs: A and T, and, G and C.
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Their mass because it can let you know their weight and size
<span>The phase of mitosis during which the mitotic spindle begins to form is
PROPHASE.
</span>At prophase, the nuclear envelope is broken down; the chromosomes disperse into the cytoplasm, condenses and become visible;
and more importantly, the mitotic spindle fibers form.