4 knowledge points of cross membrane transportation of biomass in high school selected .

In the same sucrose solution, the degree of plasma wall separation of C cells was the largest, followed by B, and A was the smallest, indicating that C cells lost the most water before the experiment, so the concentration difference with the sucrose solution was the largest, that is, the concentration of C cell fluid was the smallest, followed by B and a was the largest. After the experiment, when the plasma wall separation was no longer carried out, the concentration of the solution on both sides of the protopplasm layer was equal, so the concentration of cell fluid of B cells and C cells was equal, while the cell A cells did not have obvious plasma wall separation, indicating that the concentration of cell fluid A may be greater than or equal to sucrose solution. So choose B.

From the changes in cell morphology (mainly in the protoplasmic layer), the most obvious is the change in the volume of vacuoles, the three are in the same concentration of sucrose solution, and the morphology no longer changes, it can be judged that the concentration of B is the largest before the experiment, followed by A, and C is the smallest. The reason is simple: who loses more water, who has the greatest change in vacuolar volume, and who has the least concentration of cell fluid.

In the same sucrose solution, the degree of plasmo-wall separation of C cells was the largest, followed by A, and B did not, indicating that C cells lost the most water before the experiment, so the concentration difference with the sucrose solution was the largest, that is, the concentration of C cell fluid was the smallest, followed by A and B was the largest, so it was B>A>C. After the experiment, when the plasma wall separation was no longer carried out, the concentration of the solution on both sides of the protoplasm layer was equal, so the cell fluid concentration of A cells and C cells was equal, while the B cells did not have obvious plasma wall separation, indicating that the concentration of B cell fluid may be greater than or equal to the sucrose solution, so it was B>=A=C. So choose B.

The degree of plasmo-wall separation occurred in C cells was the largest, followed by B, and then ASo choose B.

The characteristic of transmembrane transport of substances refers to the process by which some fat-soluble substances move from the high-concentration side of the membrane to the low-concentration side. There are two main factors influencing simple diffusion:

Concentration gradient of solute molecules on both sides of the membrane. The larger the concentration gradient, the more the material diffuses along the concentration gradient; The concentration gradient disappears and the diffusion stops.

The permeability of the membrane to the substance. Because the structure of the cell membrane is a lipid bilayer, the membrane is highly permeable to highly fat-soluble substances such as oxygen and carbon dioxide, and it is easy to diffuse; Low permeability to low fat solubility and non-fat soluble substances makes diffusion difficult.

It has nothing to do with water molecules, does it?

For example, if the cell fluid concentration is 8 and the external solution concentration is 7, but in fact the cell fluid has more water than the external solution.

It has nothing to do with the number of molecules, but with the concentration of the amount of water in the substance. There is only one general idea, and that is that the water will tend to equilibrium, even if it cannot be reached. In other words, water flows from places with high concentrations of water molecules to places with low concentrations of water molecules.

From the solute point of view, it is from the place where the solute concentration is low to the place where the concentration is high. The core is still a sentence, that is, to tend to balance].

Is it movement from the outside to the inside of the cell?

In this way, it is from the inside out

It's just about concentration, isn't it?

Yes] It doesn't matter how much water you have?

It has nothing to do with the quantity, it has to do with the concentration. The direction of movement of water molecules is the direction of high solute concentration].

Yes, this is actually caused by pressure, this pressure is called osmotic pressure, and the formula or something can be checked by yourself

It's just about the concentration. Because the osmotic pressure is different depending on the concentration, the osmotic pressure is high when the concentration is high, and in order to maintain the osmotic pressure balance, the water will infiltrate to the place where the osmotic pressure is high. I have a simple method of memorization that I hope will help you: water flows higher (in high concentration).

The osmotic phenomenon is related to the concentration of the solution on both sides of the permeable membrane. Water molecules move from high concentration (low water potential) to low concentration (high water potential) at the same time, and on the other hand, they also move from low concentration (high water potential) to high concentration (low water potential), but the water molecules move more from low concentration to high concentration in the same time, so it is manifested as the high concentration solution is diluted and the low concentration solution becomes thicker.

The following is an explanation of the water potential (the content of physical chemistry, if you don't understand, you can ask your biology teacher): under isothermal isobaric, the difference in chemical potential per partial molar volume of water between water in a system (such as a cell) and pure water. It is represented by the symbol (pronounced psi) or w.

The movement of water requires energy to do work, so the movement and balance of water is a problem that belongs to "learning", which has long been described by the concept of misuse of force (such as water absorption). After the 60s, in plant physiology, the concept of water potential was widely used for the problem of water entering and leaving cells, and the concept of water potential was derived from the basic laws of thermodynamics, which was derived from free energy and chemical potential. Water potential is the strength factor that drives the movement of water.

It can be colloquially understood as the trend of water movement. Water always flows spontaneously from high to low until the two are equal. The water potential of any aqueous system is affected by various factors that can change the free energy of water (such as solute, pressure, etc.), so that the water potential of the system increases or decreases.

For example, a soluble in water can reduce the free energy of the system, reducing the water potential. The water potential of pure water is specified to be zero under standard conditions (at one atmospheric pressure, at the same temperature as the system).

By pure water, we mean pure free water that is not bound to other substances in any way (physical or chemical). It has the highest free energy content, so pure water has the highest water potential. When there is any substance dissolved in pure water, the water potential of any solution is lower than that of pure water due to the interaction of the solute (molecule or ion) with the water molecules, which consumes part of the free energy.

The more solutes in the solution, the lower the water potential of the solution.

Cells absorb water and swell when placed in clean water, while they become dehydrated in liquids where the concentration of the solution is higher than the concentration of the cells. The deformation of the middle part of the bulb in this question will be more obvious than that of the outer part.

In Figure A, the two halves of the bulb are significantly curved inward compared to the untreated cells, indicating that the inner cell volume is smaller, and the concentration of the solution that can push out a is higher than the concentration of the cell sap.

Figure B, curved outward compared to the original, illustrates that the concentration of the solution is less than the concentration of the cell fluid.

Figure C, with less curvature compared to Figure A, indicates that the concentration of solution C is less than that of solution A and greater than that of the cell fluid.

Figure D, the same as the original figure, shows that the concentration of solution D is the same as that of the cell fluid.

So, the final answer: A>C>D>B

It's very simple, just look at the stem.

Because the longitudinal cut bulb makes the cortical cells of the parenchyma cells [get rid of the shackles of the thick-walled epidermal cells, and the cortical cells expand faster], only when the cells lose water and the protoplasm shrinks, the cortical cells will "get rid of the shackles of the thick-walled epidermal cells", at this time, we believe that the more concentrated the solution, the greater the degree of contraction of the protoplasm layer, the greater the degree of shackling of the thick-walled epidermal cells, and the greater the degree of bending of the bulb to the epidermis. Accordingly, choose B

c This conclusion can be reached almost directly depending on the conditions. This mode of transport should be such that the carrier protein is required, and at the same time, the carrier protein should be saturated in the 2A solution. Both active transport and assisted proliferation are possible.

a, energy is the limiting factor, and it is not right.

b, it is determined that it is not right to facilitate proliferation.

In the case of free diffusion, the velocity should be proportional to the concentration. Exclusion D

Answer: a. The main ways in which small molecule substances or ions move in and out of cells are:

Active transport, assisted proliferation, free proliferation, etc. Active transport is from the main low concentration to high concentration, which requires carriers and energy, and it is in accordance with the needs of life activities, actively selecting and absorbing the nutrients needed. It is known that substance P is an essential small molecule substance for plant cells, and experiments have found that plant cells have the same rate of absorption of substance P in P solution at concentrations of 2A and 4A units.

So it's active shipping.

The osmosis of water belongs to free diffusion, and the general small molecules are free diffusion. Osmotic equilibrium does not mean that the concentration on both sides is the same, osmotic equilibrium simply means that at this point the cells no longer contract or expand, reaching an equilibrium. The most suitable sodium chloride solution for human cells, but it does not mean that this is the concentration of human cells, because there are also macromolecules such as proteins in the cells.

I don't quite understand about Nak ions now, but the teacher made me dizzy, which was terrible. Urea is also free diffusion, because of the fat-soluble nature of the cell membrane, lipids in general are also free diffusion. At least what is the connection between those three proteins, I can only say that they are all proteins, and they are all functional proteins.

Free diffusion is equal.

Active transportation.

1.Under normal conditions, the concentration of potassium ions in cells is much higher than that outside cells. Potassium ions enter the cell as it is actively transported, and yes.

Potassium ions exit the cell through potassium ion channels, which is an assisted diffusion.

Expand on this: high school generally knows that these are enough. Sodium ions leaving the cell are actively transported, and potassium ions entering the cell are actively transported; Potassium ions leaving the cell assists in diffusion, and sodium ions entering the cell assists in diffusion).

2.Sucrose cannot pass through the protoplasmic layer, so sucrose is used in plasma wall separation experiments.

3.ATP synthesized by chloroplasts cannot enter the nucleus. The chloroplast photoreaction synthesizes ATP, and the dark reaction consumes ATP, which is self-sufficient and cannot enter other cellular structures.

4.Ions cannot pass freely through the phospholipid bilayer, they are transported from the low-concentration side to the high-concentration side, they need the assistance of carrier proteins, and they also need to consume the energy released by the chemical reactions in the cell, so they cannot be freely diffused.

1 One is a pump and the other is an ion channel. The former is actively transporting and the latter is passively transporting.

2. 3 Chloroplast light reaction synthesizes ATP, dark reaction consumes ATP, ATP is self-sufficient and cannot enter other cell structures.

4. Generally, no.

There is active transport of potassium ions and protein-mediated facilitated diffusion (which is what you often call assisted diffusion), and so far all I know is that it is protein-mediated, and there should be no free diffusion. Molecules like sucrose should not directly enter the cell, sucrose must be hydrolyzed into glucose and fructose for absorption, and simple sugars such as glucose and fructose must enter human cells through assisted diffusion. Larger protein molecules move in and out of the cell by endocytosis.

1. Passive transport (this is the case for general cells); Opening and closing of ion channels (when nerve cells are transmitted).

2. No, (this principle is applied to the separation of the plasma wall).

3. Pass through the nuclear pores.

4. No, either passive transfer or through ion pump.

1.Active transport Passive transport Some plants require potassium ions.

2 can not 3 enter through the nuclear pore.

4 If it is free diffusion, it will disrupt the osmotic balance, and if you eat a few more handfuls of salt, the body fluids will become very salty.

1. There are also other forms of transportation, high school does not study.

2. Sucrose can't.

3. The ATP molecule is smaller and can pass through the nuclear membrane (the nuclear membrane is looser)4 with 1

1 active transport 2 can not 3ATP synthesized by chloroplasts cannot enter the nucleus 4 and can pass through the ion pump.

1.I've only learned to have active transfers. The biology class is not so absolute, there may be others.

3.The ATP that chloroplasts synthesize doesn't go out, it only feeds its own carbon reactions.

4.I don't know.

1 Most of them are active shipments.

2 No, even if it can enter the cell, it cannot be said to pass through endocytosis and cytosis is not considered to pass through3 The ATP synthesized by chloroplasts cannot enter the nucleus!

4 Most of the transportation methods of ions are active transportation = = But whether there is free diffusion, I really don't know, I think there is, but I don't know what the college entrance examination proposition expert thinks, it's like the base of the organism is obviously more than what we learn, but the college entrance examination proposition expert did not update his information base...

For the questioner in the question supplement is the question: Gases are freely diffusing in the cell and do not consume energy so mitochondria are not needed.

Before I ask a question, I'll tell the questioner a few definitions.

Free diffusion: refers to the transport of substances from the side with high concentration through the cell membrane to the side with low concentration, such as O2, CO2, N2, glycerol, ethanol, benzene and other substances, which can be transported from the side with high concentration to the side with low concentration. The way this substance enters and exits the cell is called free diffusion.

Free diffusion does not require the consumption of energy released by intracellular metabolism and is a simple mode of transportation.

Assisted diffusion: refers to a transportation mode in which non-fat-soluble substances or hydrophilic substances, such as amino acids, sugars and metal ions, enter the membrane without consuming ATP with the help of the help of membrane proteins on the cell membrane.

Free diffusion and assisted diffusion as compared to active transport are called passive transport

Active transport: Definition: A transport mode in which a specific transport protein consumes energy to allow ions or small molecules to cross a membrane against a concentration gradient.

It refers to the process of transporting substances into or out of the cell membrane under the action of energy with the assistance of the carrier against the concentration gradient. Plasma Na+, K+, and Ca2+ do not move freely through the phospholipid bilayer, and they are transported from the low-concentration side to the high-concentration side, requiring the assistance of carrier proteins and consuming the energy released by intracellular chemical reactions.

The role of mitochondria is to carry out respiration and provide energy for life activities

It's free diffusion, it doesn't consume energy, it's free diffusion, it's energy that ions need to get in and out of the cell, and it's active transport.

Active transport So choose 3 4

Do you understand.