Answer:
The correct answer is: Attachment.
Explanation:
- Pilus are thread like structures which are present on the surface of the bacterial cell.
- They are mainly responsible for attaching the bacterial cells to a substrate, for obtaining food or to an eukaryotic cell for the purpose of infection.
- Pilus also mediate the process of conjugation in some bacterial cells.
- Conjugation is a process by which genetic material or plasmids are transferred from one bacteria to another through a channel formed in between the two bacteria by the help of the pilus.
- Pilus also helps the bacteria by preventing them from getting recognised by the immune cells in the host.
- A defective pilus will affect all the above processes, resulting in death of the bacteria.
Habitat destruction
:
Habitat destruction is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or die, thereby reducing biodiversity and species abundance.
The two membranes pull apart a little and create a small pocket or sack of air. As the developing bird grows, it breathes in oxygen from the air sack and exhales carbon dioxide. Several thousand microscopic pores all over the surface of the egg allow the CO2 to escape and fresh air to get in.
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Answer:
Crossing over during meiosis is responsible for the occurance of genetic variation in living organisms.
Explanation:
Crossing over occurs in the meiosis in which parts of chromosomes are exchanged between two different chromatids which causes variation in the organisms. This occurs between two non sister homologous chromosomes. Due to crossing over, organisms that are produced is different from their parents.
