Answer:
Answer No 1:
The earliest evidence for the occurrence of viruses was the discovery of an infectious agent in the sap of a tobacco plant. Experiments were set with different filters from which bacteria could pass but viruses being even smaller than bacteria could not pass.
Viruses were difficult to study because they are very small and couldn't be seen even under a microscope.
Answer No 2:
Wendell Stanley made his studies on the tobacco mosaic virus (TMV). Wendell Stanley developed techniques and crystallized this virus. At that time, it was known that even a very simple cell does not undergo crytallization. Hence, Wendell Stanley got to known that this structure is some infectious agent which has the ability of crystallization.
Answer No 3:
The four forms of viral genomes are:
- double-stranded DNA
- single-stranded DNA
- double-stranded RNA
- single-stranded RNA.
Answer No 4:
The capsid can be described as proteins which make up a shell to enclose the genome of a virus. Capsomeres can be described as the protein sub-units from which a capsid is made. The shapes of a capsid can be characterized into
- rod-shaped: helical viruses, or inside spherical viruses
.
- icosohedral: icosohedral viruses or the heads of bacteriophages.
Answer No 5:
The components of a viral envelope involve phospholipids and membrane proteins and proteins and glycoproteins. The phospholipids and membrane proteins are derived from the host cell. The proteins and glycoproteins are of the viral origin.
As the earth has active tectonics we know that rocks are recycled and the oldest rocks may therefore just be the oldest rocks that have not been recycled yet. We know the true age of the earth by looking at radioactive isotopes of things like spacedust and meteors that formed at the same time as the earth as they have not been affected by the tectonic process of recycling here on Earth.
.........……………………........
Answer:
Many farmers use chemical herbicides to kill weeds and
insecticides to kill insects. Using genetic engineering, scientists
have developed ways to resist harmful crop pests. In this Gizmo,
you will use genetic engineering techniques to create genetically
modified corn.
Explanation:
Many farmers use chemical herbicides to kill weeds and
insecticides to kill insects. Using genetic engineering, scientists
have developed ways to resist harmful crop pests. In this Gizmo,
you will use genetic engineering techniques to create genetically
modified corn.
