Answer:
d. RNA polymerase II.
Explanation:
The main enzyme responsible for RNA synthesis is RNA polymerase, which <em>catalyzes the polymerization of 5'-triphosphate ribonucleosides (NTP) </em>directed by a DNA mold.
Eukaryotic cells contain <u>three types of nuclear RNA polymerases</u> that transcribe different types of genes. Protein-encoding genes are transcribed by RNA polymerase II to give mRNA.
 
        
             
        
        
        
321mL times 6 equals to 1926mL
1926mL in Liters is 1.926L
 
        
             
        
        
        
Answer:
Letter B.
Explanation:
Aquaporins, also known as "water channels," are the main transport of water through the membranes of plant, animal, and bacterial cells. These channels allow the water to travel into and within cells and, at the same time, exclude the passage of ions and solutes.
What makes letter B the correct answer, is the form of transport and shape of the channel that allow water according to the osmotic gradient. In this model, letter A shows simple diffusion, while C and D seem to illustrate gated channels.
 
        
             
        
        
        
In human blood, there is a compound inside the RBCs called haemoglobin which ensures that the muscle will receive enough oxygen during exercise. 
<h3><u>Explanation:</u></h3>
In human blood, the red blood corpuscles contain the haemoglobin. Haemoglobin is a iron chelated compound containing porphyrin ring and a globin tail which can establish co-ordinate covalent bond with both oxygen and carbon dioxide. The bonding element depends on the concentration of these two gases. In lungs, where the oxygen concentration is more than carbon dioxide, the haemoglobin bonds with oxygen and brings it to the tissues where carbon dioxide concentration is more. This makes the haemoglobin to release oxygen and bond with carbon dioxide which is brought back to lungs. This is the process by which each and every tissue including the muscles recieve oxygen.
In muscles there is Myoglobin which is another iron-porphyrin compound which has several times more affinity for oxygen than haemoglobin. This helps to extract more oxygen from haemoglobin in muscles.