I think the correct answer is receptor. To respond to a chemical signal a cell must have a receptor and also this where the signaling molecule can bind. A receptor is a protein molecule that can receive signals from the outside environment of the cell.
Answer: B
Explanation: Traits usually die off when they are unneeded by the organism, or if the trait causes harm to the organism's survival. Through natural selection, over time, the organisms with the best combination of traits for its survival will become the dominating species, and those with weaker traits may not survive long enough to pass off their traits to future offspring.
Cellular Respiration
Explanation:
For something to be living it doesn't need to be a cell or do photosynthesis. Cellular Respiration is the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities
1) pathogen
2) viruses
Some bacteria are not harmful to your body hence not all of them are pathogens
