The cell has to use active transport when it's trying to transport material against the concentration gradient. (from low to high concentration) Or, if a molecule is too big to diffuse through the cell membrane, it must be moved through using a carrier protein.
Hope that helped you.
Answer:
Human cells and bacterial cells both have mitochondrial and dna. human and bacteria cells share common genes.
Because it requires air, or oxygen to complete. Aerobic means with air. Therefor, cellular respiration is an aerobic process. I hope this helps, if you have a question, feel free to ask !
The correct answer is A. "A sperm cell and an egg cell combine to form an embryo."
