B is the most effective and feasible, and it prevents the initial introdution of the species
Flu vaccines need to be revised and changed every year because the flu virus constantly mutates. Flu viruses can change in two ways: drift or shift. Antigenic drift occurs when genes of the virus slowly change during replication until the immune system no longer recognizes it. On the other hand, antigenic shift occurs when a major change in the virus happens. This usually leads to a totally different kind of virus. This is what happened during the H1N1 scare in 2009.
DNA viruses like mumps are less prone to mutation due to the presence of DNA polymerase. RNA viruses are more prone to mutation because they undergo reverse transcription to simulate the role of DNA.
Indeterminate cleavage results in identical cells capable of forming an embryo while determinate cells do not result in cells which are capable to develop embryo.
Indeterminate is superior to determinate cleavage.
Explanation:
Cleavage is the division of cells in the early embryonic stage. The two stages of cleavage described here are:
In indeterminate cleavage or regulative cleavage occurs when an embryo divides, each cell is capable of developing into complete embryo. eg: Deuterosomes
In determinate cleavage the resulting embryonic cells of blastomere cannot develop into embryos. It is also called as mosaic cleavage. The essential part of the cell might be missing which does not let the cell survive. eg: Protosomes
Indeterminate cleavage is of great importance as the cell grows and can produce new organism. The complete identical twin is formed. Its application can be seen in tomato plants.
3. All animals do not display intermediate cleavage because growth from intermediate cleavage is continuous and does not stop after adulthood which is not possible in animals.
I think it's fight or flight
Answer:
a. All of these statements are true
Explanation:
The fovea is a region of the retina that’s densely packed with cones, a type of photoreceptor (a cell that detects light). The other type of photoreceptor is the rod.
While <u>rods function at low light levels</u> and allow night vision, they can’t distinguish color. In contrast, <u>cones function at high light levels and provide color vision</u>.
That's why you can't perfectly distinguish colors in a dark place.
