The answer is two and four hope this helps
C. alive. The vaccine contains a live strain of varicella-zoster (chicken pox) virus which has been attenuated so that it will stimulates the immune system but does not cause any disease in healthy people.
Answer:
Indirect contact transmission occurs when there is no direct human-to-human contact.
Explanation:
There are two types of contact transmission: direct and indirect. Direct contact transmission occurs when there is physical contact between an infected person and a susceptible person. Indirect contact transmission occurs when there is no direct human-to-human contact.
Answer;
Heterozygote advantage occurs when heterozygotes have a higher fitness than do both homozygotes. In frequency-dependant selection, the fitness of a phenotype declines it it becomes too common in the population.
Explanation;
The heterozygotes have both alleles, which is needed for genetic variation. Heterozygotes are essential for there to be genetic variation in a population. In other words it is when When a single copy of a disease allele doesn't result in a disease but instead is good for the person or organism that carries it, we say that allele has a heterozygote advantage. For example a sickle cell trait, which protects against malaria in heterozygotes, but causes a deadly disease in homozygotes.
-Frequency-dependent selection occurs when the fitness of a genotype depends on its frequency. It is possible for the fitness of a genotype to increase (positively frequency-dependent) or decrease (negatively frequency-dependent) as the genotype frequency in the population increases.
