1. Memory cells that trigger a secondary immune response
2. Specific antibodies that remain concentrated in the bloodstream for life after the first infection event
3. Memory cells that trigger a primary immune response
4. T cells that trigger a primary immune response
Answer:
1. Memory cells that trigger a secondary immune response
Explanation:
During the first infection when the body is invaded by a particular antigen, the immune system tries to identify the type of antigen. B lymphocytes make antibodies when the antigen has been identified in the event of a primary infection. The response of the immune system during the primary infection of that pathogen is usually slow. As soon as the primary infection is arrested by the antibodies produced in response, memory cells such as the memory B cells is formed, which enables the immune system to identify the same pathogen, and thereby triggers a faster secondary immune response in subsequent infections by the same pathogen.
Answer:
D. By blocking fish migration.
Explanation:
The pictured waterfalls are artificial.
The construction of the wall to raise water level for the falls to be created cuts the contact between marine organisms.
The fish on the other end of the fall cannot freely migrate to the other side.
This is because the falls are too dangerous for them and can lead to their death.
This means that the pictured method of power generation is not environmental friendly.
Answer:
if this is a true or false, then it is true
Explanation:
Answer:
E) Both Bacillus and Clostridium.
Explanation:
Bacterial endospores production is part of its survival mechanism. Bacteria produces these highly resistant spores that lies dormant in vegetative state, used during unfavourable and stressful environmental conditions. They are produced by gram positive bacteria such as Bacillus and Clostridium, and can lay dormant for years. Endospores are non-reproductive structures resistant to radiations, starvation and chemical disinfectants.
Answer:
Bacterial DNA is a double-stranded helix that has to separate its strands during replication. The unwinding of DNA strands at the replication fork creates twists farther down the helix that need to be relaxed by DNA gyrase. Ciprofloxacin inhibits this enzyme to block DNA synthesis and stop the deadly bacteria from growing.
Explanation:
DNA which stands for deoxyribonucleic acid is the molecules that stores genetic information in most living organisms. For successive reproduction to take place as well as growth to occurs in organisms, the genetic information stored in the DNA must be copied into new cells. This is achieved through the process of DNA replication.
DNA is a double-stranded molecule that is helical in shape. For replication to occur, the double strands has to be separated so that the information stored within can be accessed and then copied. DNA helicases are enzymes which are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied. The unwinding of DNA strands at the replication fork creates twists farther down the helix that need to be relaxed otherwise, the DNA strands will break. The enzyme responsible for relaxation these twists is known as DNA gyrase. Thus, any drug like Ciprofloxacin than inhibits DNA gyrase will block the DNA replication process in bacteria thereby stopping the growth of the bacteria.
