1. List Earth's four layers, in order, and tell what makes up each layer. 2. What is Earth's thinnest layer?
3. Which layer has the lowest density?
4. What evidence has geologist used that tells them Earth has four layers?

1. The Earth is made up of the inner core (center of earth; hot, dense ball of iron), outer core (surrounding inner core; made up of iron and nickel), the mantle (liquid layer, made up of bits and pieces of other layers), and the crust (the outermost layer of the Earth; the ground we walk on)

2. Earth’s thinnest layer is the crust, amounting for less than 1% of this planet’s volume.

3. The densest layer is the solid metal inner core, the mantle is of intermediate density, and the least dense layer is the lithosphere, particularly the continental lithosphere.

4. Scientists look at these happenings regarding the Earth to find out more about its layers:

1. Seismic waves and earthquakes

2. Volcanoes

3. Principles of density

4. Earth is magnetic

Hope this helps.

Explanation:

regulation of gene expression. gene expression can be regulated by various cellular processes with the aim to control the amount and nature of the expressed genes. these regulatory proteins bind to dna and send signals that indirectly control the rate of gene expression

explanation:

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.