Answer:
They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste,and the deep biosphere of the earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only about 27 percent of the bacterial phyla have species that can be grown in the laboratory.[5] The study of bacteria is known as bacteriology, a branch of microbiology.
viruse
A virus is a small infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.
The first and the fourth test tube exhibit a redish/brown color and the second and third test tubes show a dark blue/black color.
This variation exists due to the fact that amylase was added to the first and fourth test tubes. Amylase acts upon starch and breaks it down to simpler molecules. Therefore, when the IKI solution is added to check for the presence of starch, a negative result is shown. Meanwhile, the starch in the second and third test tubes remained and the IKI test showed a positive result for the presence of starch.
Answer:
A. The I bands and H bands get smaller and the A bands remain the same size.
Explanation:
The dark-colored central region of the sarcomere that extends the entire length of the thick filaments makes the A band. It also includes the part of the thin filaments that overlap the thick filaments. The lighter region of the sarcomere consisting of the rest of the thin filament but no thick filament makes the I band. The H zone is the narrow region present in the center of each A band and consists only of thick filaments.
During muscle contraction, myosin heads pull the thin filaments towards the M line. This makes the thin filaments to slide inward to allow their ends to overlap and meet at the center of the sarcomere. This makes the I band and H zone narrower. The I band and H zone are disappeared during maximum muscle contraction. Sliding of thin filaments does not change the width of A band which remains unchanged.