The given question says that a student has constructed a model of cellular transport using fences and several gates.
This model can be used to demonstrate the cellular transport.
The gates of the fences can be supposed as the protein pumps and the other fence demonstrates the lipid bilayer.
Let’s suppose in the fence, there are many cattles, and outside, there are less cattles, but the student open the gate and bring more cattles inside the fence. In this case, the transport of the cattles is similar to the active transport of the molecules using protein pumps. At cellular level, the energy for the active transport is provided by ATP molecules.
Now, let’s say, the student wants to feed the cattles with some nutrition rich food, which can help in maintaining the health of the cattles. The student fills his car with the cattle food and he enters inside the fence through gates. In this case, the food was not present in the fence, but was abundant in the outside environment, so, the diffusion would occur. But food cannot come self, without help of others, so, the movement is facilitated by the car, as it is done by the carrier proteins. Hence, it is an example of facilitated diffusion.
I think is D Carbon dioxide
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Listed under are the 5 different type of cells found in the epidermis and their description:
1. Stem cells
These are what you call undifferentiated cells. These are cells found in the stratum basale, which is the deapest layer of the epidermis. These cells divide to create keratinocytes.
2. Keratinocytes
The make up the majority of the cells in the epidermis. They synthesize keratin which are proteins that make up your hair, skin, and nails. They can also be found in other organs inside your body.
3. Melanocytes
These cells can only be found in the stratum basale. They synthesize melanin with a brown to black pigment. These dark pigments serves as protection for the skin from harmful UV rays.
4.Merkel cells
Merkel cells are also known as <em>tactile cells</em>. They are the sensory receptor for touch. Merkel cells and the nerve fiber together are called the Merkel disc.
5. Dentritic cells
They are also known as <em>Langerhans cells</em>. They can be found in two layers of the epidermis: the stratum spinosm; and stratum granulosm. They are what you call macrophages that come from the bone marrow. They serve as immune cells that provide protection against toxins, microbes and other pathogens that try to penetrate the skin.
Hope you find some information above that will help you.
Answer:
ok where is it
we can help only if there is something attached
