Answer:
option D
Explanation:
how the plant growth will be enhanced, so it seems incorrect.
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.
Crossing over does helps in genetic diversity as it provides with new genes combinations. In crossing over, chromatids exchange genetic information during the meiosis. This mixing of genetic information provides the offspring with its own unique genetic makeup with some similarities with the parent’s genetic system. Crossing over is very beneficial in terms of giving the offspring more variability that helps in becoming more resistant to a disease and be a better version than parents.
