Answer:
Channel proteins and Carrier proteins
Explanation:
These are type of membrane proteins that transcend the entire length of phosphoslipid bi- layer in the plasma membrane.They facilitate the movement of ions and molecules across the walls of the plasma membranes.
Generally, substances like glucose, amino acids, are too large to pass through the phopholipid bilayers. Likewise ions of potassium, sodium calcium, because of their polarities can not pass through either. They are ferried across the phospholipid by group of protein structures called channel proteins. Some are also transported across by carrier proteins. The process by which these protein structures aided the diffusion of substances across the phospholipid bilayer is called Facilitated diffusion.
Channel proteins are pores, that are filled with water molecules with the entrance well gated. That is the entrance is controlled by part in the inner structure of the protein which can open or close the pores like a gate to control the movement of ions across it. e.g Sodium channels are gated for movement of sodium ions by voltage or ligands(chemicals) during nervous transmission to elicits action potential. Like wise Potassium channels allow diffusion of potassium ions across the phospholipid bilayers. it gates are shut when sodium channels are open; this regulate ion exchange.
Their structures are well fixed in shape , specific to the substance or ions being transported;and the rate of diffusion depends on the like hood of opening of the gate or closure.
Carrier molecules also in the membranes do not have a fixed shape, and their transport direction is determined by the direction of concentration gradients. Thus they can flip on either sides of the membranes to aid diffusion across. Their movement can be both passive and active, and the rates of diffusion depends on the number of available carrier proteins in the membrane. They are also specific to the ions they transport.And are not gated,
Therefore these two membrane integral proteins facilitate movements of substances across the phospholipild bilayers
Answer:
The nervous system is composed predominantly of neural tissue.
Explanation: Anatomist study anatomy, the study of the structure of organisms or their parts. By observing the structure of the nervous system, anatomist will tell that it is composed predominantly of neural tissue. So, he observed the structure of one part of an organism.
<span>The characteristics that scientists used to classify living organisms into six kingdoms include the following:
1. Cell type: living organisms are classified into prokaryotes and eukaryotes based on the presence of nucleus and distinct arrangement of the organelles in their cells.
2. Mobility: living organisms are categorized into kingdoms based on their ability or inability to move about.
3. Cell structure: the cells structure was used to divide living organisms into plants and animals. Those living organisms that have cell wall are classified as plants while those who do not have cell wall are classified as animals.
4. Number of cells: living organisms that are made up of only one cell are classified as unicellular while those with many cells are termed multi cellular.
5. Reproduction method: living organisms are classified based on whether they reproduce sexually or asexually.
6. Manner of obtaining energy: living organisms that can prouduce their own food are called autotrophs while those that can not produce their own foood are termed heterotrophs. Plants are essentially categorised as autotrophs while animals are described as heterotrophs.</span>
THE TWO MOST COMMON REASON FOR MODIFYING THE LAND IN SOUTH AND SOUTH ASIA IS
(i) first is significantly, the area of lands categorized as under forest/woodland and wetlands declined .At the same time, cultivated area increased .
(ii) another is requirement of additional land due to increase in population.
Explanation:
Between 1880 and 1980, the South and Southeast Asian landscape underwent dramatic modification.The 81% of the lost forest and wetland vegetation appears to have been converted into expanded agricultural land.
Human population in this region more than tripled between 1880 and 1980, producing an enormous demand for additional land for cultivation.
