Answer: Like the thread, molecule of DNA is so thin, around 2 nm in length so, it cannot be seen with the naked eye. When DNA is clumped together, it is visible. To see or examine the DNA, it must be isolated from the cell and examine under microscope. Strands of DNA should be released from the nuclei of the cell and should be separated from other components such as histone protein around which it is coiled, before examining it.
Obstructive lung diseases include conditions that make it hard to exhale all the air in the lungs. People with restrictive lung disease have difficulty fully expanding their lungs with air.
