Prokaryotic bacteria are surrounded by a cell membrane that contains the transport proteins to regulate the entry and exit of materials through the cell, the cell wall to help maintain cell shape and structure, and the capsule, which aids against drying out and protects bacteria from a host's immune system.
<h3><u>Explanation:</u></h3>
Bacteria are the prokaryotic organisms that are found in every part of Earth. These organisms do have an interesting ultrastructure. The coverings of the bacteria are three in layer. They are
A. The outer capsule.
B. The middle cell wall.
C. The inner cell membrane.
The capsule is the outermost covering of bacteria that is formed of different slimy materials. These materials contains hygroscopic substances which can absorb water from the surroundings even when the water concentration in outside is very very low. This layer of protection outside bacteria help them to protect themselves against drying out at dry conditions.
The middle cell wall is formed of polymers of N acetyl glucosamine and N acetyl muramic acid. This layer is chitin in nature and is strong enough to maintain the shape and size of bacteria irrespective of outer conditions.
The innermost layer of bacteria is cell membrane which is formed of proteins and lipids bilayer and this cell membrane contains different transport for proteins which help in transport of different substances like water and nutrients inside the cell by means of active transport or passive diffusion.
Adrenaline
Nicotine is a substance that is addictive in nature commonly
found in cigarette, that affect the nervous system by binding to the receptors
in the brain and other part of the body. Atherosclerosis is the loss of
elasticity or thickens of arteries walls. However, nicotine increases the
release of neurotransmitter adrenaline into the blood which subsequently cause
the development of atherosclerosis.
Answer: Mercury has been well known as an environmental pollutant for several decades. As early as the 1950's it was established that emissions of mercury to the environment could have serious effects on human health. These early studies demonstrated that fish and other wildlife from various ecosystems commonly attain mercury levels of toxicological concern when directly affected by mercury-containing emissions from human-related activities. Human health concerns arise when fish and wildlife from these ecosystems are consumed by humans.
During the past decade, a new trend has emerged with regard to mercury pollution. Investigations initiated in the late 1980's in the northern-tier states of the U.S., Canada, and Nordic countries found that fish, mainly from nutrient-poor lakes and often in very remote areas, commonly have high levels of mercury. More recent fish sampling surveys in other regions of the U.S. have shown widespread mercury contamination in streams, wet-lands, reservoirs, and lakes. To date, 33 states have issued fish consumption advisories because of mercury contamination.
These continental to global scale occurrences of mercury contamination cannot be linked to individual emissions of mercury, but instead are due to widespread air pollution. When scientists measure mercury levels in air and surface water, however, the observed levels are extraordinarily low.
Explanation:
<span>The busiest phase of the cell cycle is the interphase</span>
Answer:
According to the current fossil record, scientists believe that the life on earth began about 3.5 billion years ago.
