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.
Trees, plants, oxygen tank
Answer:
The correct answer is vertebral column and cranium
Explanation:
Vertebrates are the animals that are characterized by having backbone or vertebral column and apart from the vertebral column they also have a bony skull. Skull and vertebral column protect the brain and spinal cord in vertebrates.
Vertebrata is a subphylum under phylum Chordata and clade Craniata so vertebrates have both cranium and vertebral column. In vertebrates, notochord is present in the embryonic stage and is replaced by vertebral column in adults.
Animals that comes under the Vertebrata are fishes, mammals, reptiles, amphibians, and birds. So the correct answer is B and C.
The answer is A.
A fish is biotic because it is alive; the creek is abiotic because it is not alive.
Both the bird and the berry are biotic because they are both alive.
Explanation:
Hi!! sorry to take up this space and probably waste your time but you didn't insert a picture or equation!! I'm so sorry, I'd help you otherwise!
