Answer:
The correct option is C. A virus contains RNA or DNA in a protein coat.
Explanation:
Viruses can be described as tiny particles which are able to incorporate their genetic material into a host. Many viruses can be destructive to the host cells.
The structure of a virus includes DNA or RNA which is enclosed in a structure known as an envelope or capsid. The envelope or capsid is made up of proteins. Some viruses also have a tail.
The capsid of a virus usually remains outside the host cell and it injects its viral genome into the host cell. The DNA or RNA o the virus then incorporates in the host cell.
Answer:
Option A, oxygen in the atmosphere
Explanation:
The highest level of oxygen reached during this phase of the geological cycle of earth. The oxygen level in Carboniferous period accounted for 35% as compared to 21% of oxygen in the atmosphere in present time.
Due to high oxygen content, the giant and wide varieties of terrestrial animal and plant species evolved. For example – size of insects and carwlies increased, plant became extremely giant, increase in number of tree ferns etc.
The answer is C because there is no inference in the statement like the others.
Intercostal Muscles
The muscles of respiration
are muscles that contribute to exhalation and inhalation by causing the contraction
and expansion of the thoracic cavity. However, diaphragm is the main muscle of breathing
while intercostal muscles is one of the most important muscles for respiration.
Intercostal muscles function by manipulating the width of the rib cage and they
are attached between the ribs.
