Well, I don't fully understand your question. I think I know what you're getting at though.
In a system of sexual reproduction, you have genes coming from both an egg and the sperm. Therefore, it'll only contain half the total amount of chromosomes (46 in humans). A sperm will have 23, and the egg will have the other 23. Is that what you meant why the chromosomes are cut out in pairs? If that wasn't your question, please elaborate and I'll return to answer it to the best of my capabilities.
It will always epual the same amount of Guanine
Answer:
the surrounding ecosystem is nearly or completely destroyed this changes the physical and biological components of the system by killing any biological life and reshaping all structures with magma. this will affect the population by killing anything living haunting life for centuries until new life can start to form such as lichens to break down the hardened rocks nutrients into soil for life
Selectively permeable (or semi permeable) means where for example a membrane can choose what material can pass through while others cannot. They control the in and out of materials.
This is because the membrane has tiny spaces, where only smaller molecules can pass through, other larger ones cannot.
