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Dominik [7]
3 years ago
7

All of the following are threats to sandy beaches except:

Biology
1 answer:
babunello [35]3 years ago
4 0
Animal Movement is not a threat to sandy beaches.
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Smita observed the onion peel under microscope and noted the following observations. Lalitha marked the incorrect one. What is i
Ganezh [65]

Answer:

C

Explanation:

Irregular shape

5 0
3 years ago
A student lives in a home some few miles from a nearby coal crushing site. The vegetation and structures within the
Gnesinka [82]
The correct answer is C
7 0
2 years ago
How do temperature and concentration of monounsaturated phospholipids change the rate at which molecules permeate the plasma mem
Nikitich [7]

Answer: At low temperatures the fluidity of the membrane decreases and it favors fluidity. The higher the concentration of unsaturated fatty acids, the less tightly the phospholipids can bind and the more fluid (more permeable).

Explanation:

The plasma membrane is a lipid layer that delimits the entire cell, dividing the extracellular medium from the intracellular (the cytoplasm of a cell). They are composed of phospholipids, which are molecules composed of glycerol, a phosphate group and two lipid chains (such as fatty acids). Glycerol is a three-carbon molecule that functions as the backbone of this membrane. A geometry is formed that allows the phospholipids to line up side by side to form broad sheets. They are insoluble in water, but their unique geometry causes them to aggregate in layers without any energy input, as they possess a hydrophilic phosphate head and a hydrophobic tail consisting of the two fatty acid chains. The hydrophilic heads of the phospholipids in a bilayer membrane face outward and are in contact with the aqueous fluid inside and outside the cell. Because water is a polar molecule, it readily forms electrostatic (charge-based) interactions with the phospholipid heads.

Selective permeability is a property of the plasma membrane and other semipermeable membranes that allow only certain particles to pass through them. In this way,<u> those particles that are needed by the cell can enter the cell and those that are not useful to the cell are prevented from entering</u>. In the same way, the cell can eliminate the particles it has produced as waste. In this way, the entry and exit of substances through the membrane is regulated and the correct functioning of the cell is achieved.

For a particle to be able to cross the plasma membrane it must have a size equal to or smaller than the pores of the membrane, it must have the opposite charge to the charge of the membrane or simply have a neutral charge, and if it is larger than the pores it must be dissolved in a solution, decreasing its size and thus be able to enter the cell through the membrane.  

Plasma membranes are fluid and this fluidity depends on their lipid composition and temperature. Depending on the temperature, membrane lipids can be found in two different states or phases: gel (solid-like, with more rigid hydrocarbon chains) and liquid crystal (more fluid, with more mobile hydrocarbon chains). At low temperatures the fluidity of the membrane decreases and in these conditions the increase of its concentration favors fluidity. The temperature at which the transition from one state to the other occurs is the phase transition temperature (Tc). At values below Tc, the bilayer is in the gel state and at higher values it passes to the liquid crystal. It should be noted that there is an equilibrium between the gel state and the liquid crystal state and that the characteristics of the lipids of the bilayer condition the transition temperature. In the case of bilayers consisting of only one type of lipid, the Tc is well defined. But biological membranes are complex lipid mixtures and the transition from one state to another occurs over a range of temperatures. The presence of short-chain or unsaturated fatty acids reduces the transition temperature, while saturated fatty acids and the increase in the length of the hydrocarbon chains cause this temperature to rise. <u>Then, phospholipids with unsaturated fatty acid tails cannot bind as tightly due to the bent structure of their tails. For this reason, a membrane of unsaturated phospholipids remains fluid at lower temperatures than a membrane of saturated phospholipids</u>.  

The fluidity of a membrane is the ability of a molecule to move through it.<u> In short, the higher the concentration of unsaturated fatty acids, the less tightly the phospholipids can bind and the more fluid (more permeable) the membrane will be even at low temperatures</u>. However, <u>at low temperatures the fluidity of the membrane decreases (lower permeability) but the effect will depend on the composition of the fatty acids</u>. To determine the exact permeability, it is necessary to relate the concentration of unsaturated bonds and the length of the fatty acids in the phospholipids and the temperature.

8 0
2 years ago
Earth is tilted at a 23.5 degree angle. Explain how this causes the equator to be hot and the poles to be cold.
Agata [3.3K]

Answer:

sunlight

Explanation:

at the angle the earth is at, sunlight hits the equator almost directly, as well as the equator being closer to the sun.

8 0
2 years ago
The appearance of new technologies in Europe after the 11th century produced a variety of social consequences, both progressive
riadik2000 [5.3K]

Answer: D

Explanation:

Because the heavy plow and its traction team was expensive tool and individual peasant farmers were not able to own it, it brought collective ownership and patterns of communal agriculture and communal animal husbandry.

The heavy plough required more energy to pull this resulted several families coming together to pool their oxen to form a team large and strong enough to pull the heavy plow. The resulting “ox-gangs” became an important social group.

3 0
3 years ago
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