Answer:
B. 20%
Explanation:
The complementary base-pairing rule states that Adenine always pairs with Thymine (A with T), and Cytosine with Guanine (C with G).
Because of this, the amount of Adenine present must be the same as the amount of Thymine present, and the same for Cytosine and Guanine.
This means that if there is 30% Adenine, there is also 30% Thymine as each A base is paired to a T base. This adds to 60%, so Cytosine amounts and Guanine amounts must add to 40% to make 100%.
Since they are equal in amount, there must be 20% of each.
Therefore the answer is B. 20%
There is 30% Adenine, 30% Thymine, 20% Guanine and 20% Cytosine.
Hope this helped!
Answer:
Cartilage rings of trachea have protective role
Explanation:
Trachea is a tube, part of the respiratory system, which allows the passage of the air: from larynx to lungs (primary bronchi). It is enveloped with cartilage rings that prevent collapse of the trachea when there is no air. The cartilage "rings" are C-shaped, except one full ring-shaped - the cricoid cartilage which attaches trachea to the larynx.
Ecosystems maintain themselves by cycling energy and nutrients obtained from external sources. At the first trophic level<span>, </span>primary producers<span> (plants, algae, and some bacteria) use solar energy to produce organic plant material through photosynthesis. Herbivores—animals that feed solely on plants—make up the second trophic level. Predators that eat herbivores comprise the third trophic level; if larger predators are present, they represent still higher trophic levels. Organisms that feed at several trophic levels (for example, grizzly bears that eat berries and salmon) are classified at the highest of the trophic levels at which they feed. Decomposers, which include bacteria, fungi, molds, worms, and insects, break down wastes and dead organisms and return nutrients to the soil
I got this passage from Annenberg Learner
</span>
