A) A sound wave
The other 3 create mutations, are cells are hit by sound waves all the time and experience no mutations because of it
Answer:
proteins is the answer of this question
1. Reduces the chromosome number from diploid to haploid
2. Ensures that each of the 4 gametes has a complete set of chromosomes
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.