Answer: Option B
Explanation: The first line of defense acts a barrier and does not allows the foreign materials to enter inside the body. It includes chemical and physical barriers that are always ready to protect the body from infection.
Example: Skin and mucous membrane.
Skin is largest organ and it acts as a barrier between pathogens and human body. It acts a waterproof material and the pathogens cannot get inside through skin unless the skin is broken.
Mucous membranes also acts as first line of defense and breaks the cell wall of many bacteria entering through the openings of the body.
So, skin and mucous membrane are the first line of defense.
D. Photosynthesis only takes place in the light, while cellular respiration takes place in the light and dark.
The answer should be a mixture in which the substances are evenly spread out in biology terms.
Explanation:
In the nucleus
The DNA can be found in the Nucleus
