Answer:
This lack of fossil data is expected, because the fossil record is incomplete.
Explanation:
Fossilization is a slow, complex and extremely rare process that depends on several favorable conditions for the conservation of traces or materials left by an organism:
1 - Rapid burial of the material;
2 - Presence of rigid parts that are more resistant to degradation;
3 - The type of sediment should be thin and less prone to erosion.
4 - The environment in which the material is located should be low in oxygen to avoid degradation due to oxidation.
5 - The temperature of the place where the material is buried should preferably be cold because the action of decomposing microorganisms in these environments is much lower.
Therefore, it is very common and expected that the fossil record is incomplete.
A class of lipids derived from cholesterol are called steroids.
Steroids are important large class of biological molecules which are significant components of cell membrane and signaling molecules.
Pulmonary ventilation comprises two major steps: inspiration and expiration. Inspiration is the process that causes air to enter the lungs, and expiration is the process that causes air to leave the lungs. A respiratory cycle is one sequence of inspiration and expiration
Answer:
Herd immunity
Explanation:
Herd immunity refers to the resistance of a group of people against infection and the spread of a pathogen. It occurs when a high proportion of the members of that group are resistant against a particular pathogenic infection. When an earlier exposure or vaccination of a large proportion of individuals of a population does not allow the pathogen to spread among and infect the otherwise susceptible members of the population, the population is said to have acquired the herd immunity.
In the given example, vaccination of a large percentage of a population protected the susceptible individuals against a particular microbe. This represents an example of herd immunity.
