Answer:
<u>Option-(True):</u> The following statement is true in all sense, as the "Cytotoxic T cells and NK cells kill by secretion of proteins. The first called granzyme which forms complexes that penetrate the cell membrane and allows the passage of the apoptosis inducing protein perforin to enter the targeted cell."
Explanation:
- In order to make it more difficult for the pathogens and other foreign particles to stay inside the human body, the defense mechanism of the human body system has evolved itself to great extents as there are different level of immune layers and more over cells that either helps in the recognition of these anti-bodies or attacks them to be eliminated from the given system.
- As the hazardous or cancer cells which are not required to stay inside the human body is removed with the help of these lymphocytes inside the immune system of the human body.
Before a cell can enter cell division, it needs to take in nutrients. All of the preparations are done during interphase.<span> Interphase is a series of changes that takes place in a newly formed cell and its nucleus, before it becomes capable of division again. It is also called preparatory phase or intermitosis.</span>
Answer:
It was difficult for him to understand how the heart worked because he wasn't fully aware of the pumping mechanism of the heart and how the circulation of blood goes inside the body. Not seeing the capillaries meant that the heart pumped blood towards the vessels and into a dead end. He couldn't understand where the blood that was being pumped goes to.
Explanation:
Leonardo da Vinci is considered one of the earliest persons to study the heart. Although he made an exceptional observation of the different parts of the heart, <em>he couldn't track the capillaries</em>. <em><u>He didn't know that these </u></em><em><u>tiny structures</u></em><em><u> connected the </u></em><em><u>arteries</u></em><em><u> and the </u></em><em><u>veins.</u></em> He believed that the heart was meant to<em> transfer heat from the liver going to the muscles. </em>He also believed that<em> the lungs helped cool the blood.</em>