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.
Answer:
uniformitarianism, Fossil groups, 48 million years ago.
Explanation:
- Uniformitarianism is the doctrine of uniformity that assumes that same environmental laws and process operate till date that has also occurred on the past but not with the same uniformity. Unlike the atmospheric that is short-lived and sudden changes over the period of time.
- William Smith was a geologist who has noticed a certain type of fossil in a certain layer of sedimentary and igneous rock. A similar layer of strata could be found in the areas that were further apart.
- The Permian period was from 229 to 251 million years and was the last period of the paleozoic era and is recorded for the last major extinction in the history of life in earth and it lasted for 48 million years.
Answer: it is difficult because it is necessary to understand some concepts used in a system. For example what is a boundary, and environment which can be positive or negative, etc. A sample could be the course OpenLearn that provides an example of Computing & IT.
Explanation:
