Answer:
Oligodendrocytes in the brain and spinal cord and Schwann cells in the peripheral nervous system are specialized types of glia that build the myelin sheaths that surround neurons.
Explanation:
Myelin sheath is an insulating layer, which covers neurons. It is made up of protein and fatty substances. This myelin sheath permits electrical impulses to move very fast along the neurons.
Answer:
Explanation:
Observation is essential in science. Scientists use observation to collect and record data, which enables them to construct and then test hypotheses and theories. Scientists observe in many ways – with their own senses or with tools such as microscopes, scanners or transmitters to extend their vision or hearing
Answer:
Purple, spherical-shaped organisms arranged in chain like formations.
Explanation:
Bacteria are the microscopic organisms and included in the prokaryotes as they do not have nucleus. Two main types of bacteria are gram positive bacteria and gram negative bacteria.
The gram positive bacteria has thick cell wall peptidoglycan cell layer and can uptake the crystal voilet stain. These bacteria seems purple under the microscope due to the uptake of stain. The bacteria Streptococcus pyogenes are spherical in shape and occurs in the cluster of chain.
Thus, the correct answer is option (d).
Answer: Hydrogen bonds are created between the base pairs in DNA. Adenine pairs with thymine and cytosine pairs with guanine. Adenine and thymine create 2 hydrogen bonds while cytosine and guanine create 3. These bonds are fairly weak so that they can be broken when DNA is replicated (by an enzyme called helicase which unwinds DNA). However despite them being weak they do stabilize DNA's double helix structure as well.
