Answer:
Plants have cell walls, mammals have cell membranes.
The answer is d to the question!!!
3rd and 4th awnsers are correct
Because the earth is in an angle so the northern hemisphere receives more heat and vice versa
The skin is an example of a non-specific defense.
For example, bacteria or diseases have trouble entering a healthy person's skin because it is formed by closely packed cells with multiple layers and a substance called keratin that protects is.
On the other hand, the immune system is a specific defense mechanism.
When bacteria is able to enter the body in cases of fever for example, the immune system is activate and sends out protector cells such as the white blood cells to combat infection.
