The answer is; A
In the lymph vessels, a few lymphocytes ‘ patrol’ the tissues as they scan for antigens. When they detect an antigen, including surface antigens of rogue cells (cancer cells), the antigen-presenting cells (APCs) present this to the cognate lymphocytes turning them to effector cells (such as effector T-cells). The effector T- cells bind to the cancer cells and induce apoptosis.
Bacteria cells have no *nucleus*
Reason:
Prokaryotic cells lack most organelles, namely the nucleus, which contains genetic information and controls everything that goes on in the cell. Bacteria cells are prokaryotes, which means they do not have many of the organelles that eukaryotic cells have.
Answer:
C A Respiration means moving your muscles to draw air into the lungs. B Respiration means the diffusion of gases between the air sacs and the blood.
Explanation:
I did a lot of studing for summer school. And I worked very hard on it. I hope this helps!!!!!!
Answer: Option D.
The lub heart sound is due to the closing of atrioventricular valves.
Explanation:
Heart sounds are noises that are generated from beatings from heart and from blood that flows through it. The heart sound reflect the turbulence generated when the heart valves snap shut. Lub is the first heart sound also called S1 and it is caused by turbulence and closure of the atrioventricular valves(mitral and triscupid valves) at the start of systole. The second sound is the dub sound which caused by the closing of aortic and pulmonic valves at the end of systole.
