He is incorrect because a catalyst is a substance that speeds up a chemical reaction so if there is no reaction to begin with a catalyst will not due anything.
Urban people change their environment through their consumption of food, energy, water, and land. And in turn, the polluted urban environment affects the health and quality of life of the urban population. ... For example, urban populations consume much more food, energy, and durable goods than rural populations.
Answer:
Specialized cells are the cells though they are similar, but cells differ in size, shape and depending upon their function in body.
Example of specialized cells are: Blood cells, Nerve cells, Reproductive cells.
Tissues are made up of specialized cells, those tissues make up organs, organs make up system and systems make up bodies.
I do not know at ALL. =( Sorry.
Step One - Obtain a clean microscope slide.
Step Two - Place a drop of liquid on the slide. This is the “wet” part of the wet mount. The liquid used depends on the type of cell being viewed:
If examining a plant cell, tap water can be used.
If examining an animal cell, physiological saline (or contact lens solution) must be used, because if plain water is used, the cell will explode from osmotic pressure. Unlike plant cells and bacteria, animal cells have no cell wall to structurally support them.
Step Three - Obtain the specimen to be used. Some introductory biology classics for viewing include:
Skin of an onion bulb: In order to view the cells, a very thin layer of skin must be obtained. Take a single layer of onion and bend it towards the shiny side. After it snaps, pull gently, and a transparent layer of skin, similar to Scotch tape, will appear.
Elodea leaf: Elodea leaves are two cell layers thick. The cells in one layer are smaller than the cells in the other, so elodea leaves can be used to better understand a microscope's depth of field.
Cheek cells: Human epithelial cells can be obtained by gently rubbing a toothpick on the inside of the mouth, and then swirling the toothpick in the physiological saline on the slide.
Pond water: Obtaining some water from a pond makes wet mount preparation a breeze, since the water and the specimens are both included.
Hope this helps
