Answer:
Option A, keystone species
Explanation:
Keystone species are responsible for controlling any species from becoming dominant over all other species. The keystone species are found at the top of all the energy pyramids and food chains.
They control the explosion of population of prey and hence regulate the overall ecological diversity.
Some common example of keystone species is as follows –
Bison, prairie dog, large mammalian predators,
Hence, option A is correct
You can use dimensional analysis to figure this out.
× 
= 3 grams
If done correctly, ml and ml will cancel out, leaving you with grams.
If you don't know dimensional analysis, simply multiply <em>3 ml</em> by <em>1 grams </em>and that should still get you 3 grams.
Answer: alternating dark and light bandsof protein filaments
Skeletal muscle fibers contain striations that can be described as alternating dark and light bands of protein filaments. Actin, tropomyosin, and troponin are among the protein filaments. The dark bands are the so-called A bands. Alternating light bands are referred to as I bands.
Answer:
High amounts of melanin.
Explanation:
Dark-pigmented people living in high sunlight environments are at an advantage due to the high amounts of melanin produced in their skin. The dark pigmentation protects from DNA damage and absorbs the right amounts of UV radiation needed by the body, as well as protects against folate depletion.
Answer:
vaccines were designed by using new technologies (i.e., RNA-based vaccines and adenovirus-based vaccines)
Explanation:
RNA-based vaccines are vaccines based on the delivery of specific messenger RNA (mRNA) sequences that are capable of encoding only one viral protein, thereby preventing the complete viral cycle/replication. Subsequently, this protein is recognized by the immune system that generates memory immunity by synthesizing specific antibodies against this protein (in this case, the spike S protein). On the other hand, adenovirus-based vaccines are vaccines designed by inserting a transgene cassette into an adenovirus which is used as vector to produce one specific viral protein inside the host. Like mRNA vaccines, this antigenic viral protein is then recognized by the immune system in order to produce antibodies against a defined protein epitope, thereby producing memory immunity.
