3. Movement into and outside of the cell.pptx

IGCSE PPT

1. 2.2 Movement into and outside of the cell 进入和离开细胞

2. Drawing competition 1 st prize 2 nd prize 3 rd prize 4 th prize

3. Contents States of matter Kinetic energy Diffusion Osmosis Dialysis Water potential Tonicity Osmosis experiment

4. In a solid substance, the particles cannot move very far, because they are held together by attractive forces between them. They simply vibrate around a fixed position. 在固体物质中，粒子不能移动很远，因为它们被它们之间的吸引力结合在一起。它们只是在固定位置附近振动。 In a liquid they can move more freely but stay in contact with one another. They bump into one another and rebound. 在液体中，它们可以更自由地移动，但彼此保持联系。他们相互碰撞并反弹。 In a gas they are freer still, with no attractive forces between the molecules or atoms. When molecules and ions are in a solution, they can move as freely as when they are liquid. 在气体中，它们仍然更自由，分子或原子之间没有吸引力。当分子和离子在溶液中时，它们可以像液体一样自由移动。 States of matter 物质状态

5. Everything – including living cells – is made of atoms, molecules and ions. These particles are always moving. 一切事物 —— 包括活细胞 —— 都是由原子、分子和离子组成的。这些粒子总是在移动。 The higher the temperature, the faster they move. This is because the particles have more kinetic energy at higher temperatures. The more kinetic energy they have, the faster they move. 温度越高，它们移动得越快。这是因为粒子在较高温度下具有更大的动能。它们拥有的动能越多，它们移动得越快。 Kinetic energy 动能

6. Diffusion 扩散 The movement of molecules from an area of high concentration to an area of low concentration. 分子从高浓度区域到低浓度区域的运动 Molecules tend to “ spread out ” 分子倾向于“扩散” higher conc. lower conc. Cell membrane

7. Diffusion can occur in the air , or in the water , or across membranes . 扩散可以发生在空气中，或水中，或跨膜。 The cell membrane is semipermeable - some stuff can pass through it but not others. Imagine it like a screen door. 细胞膜是半透性的 —— 有些东西可以穿过它，但其他东西不能。把它想象成一扇纱门。 Examples: 例子： Food coloring in water 水中的食用色素 Perfume in the air 空气中弥漫着香水味

8. Diffusion down a concentration gradient 沿浓度梯度扩散 When they can move freely, particles tend to spread themselves out as evenly as they can. This happens with gases, solutions, and mixtures of liquids. 当它们可以自由移动时，粒子往往会尽可能均匀地扩散开来。这发生在气体、溶液和液体混合物中。 The hydrogen sulfide molecules quickly spread through the air in the whole room. Soon, you cannot tell where the smell first came from – the whole room smells of rotten egg! 硫化氢分子迅速扩散到整个房间的空气中。很快，你就分不清气味是从哪里来的 —— 整个房间都闻起来有臭鸡蛋的味道！ Imagine, for example, a rotten egg full of hydrogen sulfide gas in one corner of a room. Hydrogen sulfide gas is very smelly. To begin with, there is a high concentration of the gas near the egg but none in the rest of the room (Figure). 例如，想象一下，在房间的一角有一个充满硫化氢气体的臭鸡蛋。硫化氢气体非常臭。首先，鸡蛋附近有高浓度的气体，但房间的其余部分没有（图）。

9. The hydrogen sulfide molecules in rotten egg have spread out through the air. This spreading out is called diffusion . 臭鸡蛋中的硫化氢分子已经通过空气扩散开来。这种扩散称为扩散。 Diffusion happens because the molecules move randomly. They do not purposefully move from one place to another. 扩散的发生是因为分子随机移动。他们不会故意从一个地方移动到另一个地方。 Each molecule just moves by chance, changing direction when it bumps into another molecule. Some molecules might even go back into the rotten egg again. But, overall, the molecules spread evenly across the room. 每个分子只是偶然移动，当它撞到另一个分子时会改变方向。有些分子甚至可能再次回到臭鸡蛋中。但是，总的来说，分子均匀地分布在房间里。 Diffusion of hydrogen sulfide 硫化氢的扩散

10. Imagine a slope. The place with the high concentration (the rotten egg) is at the top of the slope. The place with the low concentration (the rest of the room) is at the bottom of the slope. The molecules move ‘down the slope’ from where there is a high concentration to where there is a low concentration. 想象一个斜坡。浓度高的地方（臭鸡蛋）在斜坡的顶部。浓度低的地方（房间的其余部分）位于斜坡的底部。分子从高浓度的地方“向下斜坡”移动到低浓度的地方。 Another word for ‘slope’ is ‘gradient’. We can therefore say that there is a concentration gradient from the rotten egg to the rest of the room. So, the hydrogen sulfide molecules move ‘down’ this concentration gradient. “坡度”的另一个词是“梯度”。因此，我们可以说从臭鸡蛋到房间的其余部分存在浓度梯度。因此，硫化氢分子会“向下”移动该浓度梯度。 Concentration gradient 浓度梯度

11. Osmosis 渗透 The diffusion of water across a membrane. 水在膜上的扩散 Things that can cross the cell membrane - water, oxygen , and other small molecules. 可以穿过细胞膜的东西 —— 水、氧气和其他小分子 Large molecules, like salt and sugar cannot easily pass through the cell membrane 大分子，如盐和糖，不容易穿过细胞膜

12. Water is one of the most important compounds in living organisms. It can make up around 80% of some organisms’ bodies. It has many functions, including acting as a solvent for many different substances. For example: 水是生物体中最重要的化合物之一。它可以占某些生物体身体的 80% 左右。它具有许多功能，包括充当许多不同物质的溶剂。例如： When we swallow food, some of it dissolves in water in the alimentary canal, where it can be acted on by enzymes which are also dissolved in water. 当我们吞咽食物时，其中一些会溶解在消化道中的水中，在那里它可以被同样溶解在水中的酶作用。 Osmosis in digestion 消化中的渗透作用

13. • the kidneys excrete urea dissolved in water, to form urine 肾脏排泄溶解在水中的尿素，形成尿液 •substances are transported around the body dissolved in the water in blood plasma. 物质在溶解在血浆中的水中在身体周围运输。 Osmosis in excretion and blood transport 排泄和血液运输中的渗透作用

14. Every cell in an organism’s body has water inside it and outside it. Many different substances are dissolved in this water, and their concentrations may be different inside and outside the cell. This creates concentration gradients, down which water and solutes will diffuse, if they are able to pass through the membrane. 生物体内的每个细胞内部和外部都有水。许多不同的物质溶解在这种水中，它们的浓度在细胞内外可能不同。这会产生浓度梯度，如果水和溶质能够穿过膜，它们就会向下扩散。 Osmosis 渗透 This figure illustrates a concentrated sugar solution, separated from a dilute sugar solution by a membrane. The membrane has holes or pores in it which are very small. An example of a membrane like this is dialysis tubing. 该图示出了通过膜与稀糖溶液分离的浓缩糖溶液。膜上有非常小的孔或孔。像这样的膜的一个例子是透析管。

15. In dialysis tubing, the holes are big enough to let the water molecules through, but not the sugar molecules. Dialysis tubing is called a partially permeable membrane because it will let some molecules through but not others. 在透析管中，孔足够大，可以让水分子通过，但不能让糖分子通过。透析管被称为部分渗透膜，因为它会让一些分子通过，但不会让其他分子通过。 Dialysis 透析 There is also a concentration gradient for the water molecules. On the left-hand side of the membrane, there is a high concentration of water molecules. On the right-hand side, the concentration of water molecules is lower because a lot of space is taken up by sugar molecules. 水分子也存在浓度梯度。在膜的左侧，有高浓度的水分子。在右手边，水分子的浓度较低，因为糖分子占据了大量空间。

16. Because there are more water molecules on the left-hand side, at any one moment more of them will ‘hit’ a hole in the membrane and move through to the other side than will go the other way (right to left). Over time, there will be an overall, or net, movement of water from left to right. This is called osmosis. 因为左手边有更多的水分子，所以在任何时候，它们都会“击中”膜上的一个孔并移动到另一侧，而不是向另一侧移动（从右到左）。随着时间的流逝，水将从左到右进行整体或净运动。这称为渗透。 Dialysis 透析

17. The term concentration is normally used to mean the concentration of the solute dissolved in the water. It is much better to use a different term. It can be potential . We say that a dilute solution (where there is a lot of water) has a high-water potential . A concentrated solution (where there is less water) has a low water potential . Water potential 水势 术语浓度通常用于表示溶解在水中的溶质的浓度。使用不同的术语要好得多。它可能是潜在的。 我们说稀溶液（有很多水）具有很高的水潜力。浓缩溶液（水较少）的水势较低。

18. In Figure, there is a high-water potential on the lefthand side and a low water potential on the right-hand side. There is a water potential gradient between the two sides. The water molecules diffuse down this gradient, from a high-water potential to a low water potential. 在图中，左侧水位较高，右侧水势较低。两侧之间存在水势梯度。水分子沿着这个梯度扩散，从高水势到低水势。 Water potential and osmosis are of great importance to organisms because they affect how and when organisms take up and lose water. Water potential gradient 水势梯度 水势和渗透作用对生物体非常重要，因为它们会影响生物体吸收和失去水分的方式和时间。

19. Osmosis and animal cells 渗透和动物细胞 Osmosis happens when two solutions (or a solution and pure water) are separated from each other by a partially permeable membrane. The membrane lets water molecules through, but not the other molecules that are dissolved in the water. 当两种溶液（或溶液和纯水）被部分渗透膜彼此分离时，就会发生渗透。膜让水分子通过，但不能让溶解在水中的其他分子通过。 Cell membranes are partially permeable. They let water through easily, but other molecules and ions often cannot get through. This means that osmosis happens across cell membranes. 细胞膜是部分可渗透的。它们很容易让水通过，但其他分子和离子通常无法通过。这意味着渗透发生在细胞膜上。

20. Figure shows an animal cell in pure water. The cytoplasm inside the cell is a fairly concentrated solution. The proteins and many other substances dissolved in it are too large to get through the cell membrane. However, water molecules can get through the membrane. 图为纯水中的动物细胞。细胞内的细胞质是一种相当浓缩的溶液。溶解在其中的蛋白质和许多其他物质太大而无法通过细胞膜。然而，水分子可以穿过膜。 Osmosis and animal cells 渗透和动物细胞

21. Figure shows an animal cell in a concentrated solution. If this solution is more concentrated than the cytoplasm, then water molecules will diffuse out of the cell. Look at this figure to see why. As the water molecules go out through the cell membrane, the cytoplasm shrinks, so the cell gets smaller. 图示为浓缩溶液中的动物细胞。如果这种溶液比细胞质更浓缩，那么水分子就会扩散到细胞外。看看这个数字就知道为什么了。当水分子通过细胞膜排出时，细胞质会收缩，因此细胞会变小。 Osmosis and animal cells 渗透和动物细胞

22. U - Tubes (not just for videos!) With an elbow partner, discuss what you think is happening in this illustration. Be prepared to share with the class.

23. Tonicity  is the relative concentration of solute (particles), and therefore also a solvent (water), outside the cell compared with inside the cell.

24. Cells In Different Solutions " ISO " means the same

25. Hypo = less

26. Hyper = more Cell will shrink or die, plants wilt Why is it dangerous to drink sea water? Why does pouring salt on a slug kill it?

27. • An  isotonic solution  has the same concentration of solute (and therefore of free water) as the cell. When cells are placed in an isotonic solution, there is no net movement of water. • A  hypertonic solution  has a higher solute (therefore, lower free water) concentration than the cell. When cells are placed in a hypertonic solution, water moves out of the cell into the lower free water solution. • A  hypotonic solution  has a lower solute (therefore, higher free water) concentration than the cell. When cells are placed in a hypotonic solution, water moves into the cell from the higher free water solution.

28. Experiment with potato

29. 2 1 3 4 5 6 7 8 9

30. Salt conc. (g/100ml) Initial potato strip length (cm) Final potato strip length (cm) Change in length (%) Average change in length (%) 1 2 3 4 5

31. Graph paper

32. Passive Transport Requires no energy ! Diffusion Osmosis Facilitated Diffusion (helper proteins move things across)

33. A plant cell in this state is rather like a blown-up tyre – tight and firm. It is said to be turgid . The pressure of the water pushing outwards on the cell wall is called turgor pressure. Turgor pressure helps a plant that has no wood in it to stay upright and keeps the leaves firm. Plant cells are usually turgid. Turgidity 浑浊 图示为浓缩溶液中的动物细胞。如果这种溶液比细胞质更浓缩，那么水分子就会扩散到细胞外。看看这个数字就知道为什么了。当水分子通过细胞膜排出时，细胞质会收缩，因此细胞会变小。

34. When a plant cell loses a lot of water, it also loses its turgor pressure. The contents of the cell do not push outwards on the cell wall, so the cell becomes soft and floppy. It is said to be flaccid . 当植物细胞失去大量水分时，它也会失去膨胀压力。细胞的内容物不会在细胞壁上向外推，因此细胞变得柔软和松软。据说是松弛的。 If the cells in a plant become flaccid, the plant loses its firmness and begins to wilt. When the cell membrane tears away from the cell wall, the cell is said to be plasmolyzed . 如果植物中的细胞变得松弛，植物就会失去硬度并开始枯萎。当细胞膜从细胞壁上撕裂时，细胞被称为等离子体分解。 Plasmolysis 等离子体溶解

35. Plasmolysis can kill a plant cell because the cell membrane is damaged as it tears away from the cell wall. Plasmolysis 等离子体溶解 等离子体分解可以杀死植物细胞，因为细胞膜在从细胞壁上撕裂时会受损。

36. In plants, for example, root hair cells take in nitrate ions from the soil. The concentration of nitrate ions inside the root hair cell is usually higher than their concentration in the soil. The diffusion gradient for the nitrate ions is out of the root hair, and into the soil. But the root hair cells are still able to take nitrate ions in, using active transport. 例如，在植物中，根毛细胞从土壤中吸收硝酸根离子。根毛细胞内硝酸根离子的浓度通常高于它们在土壤中的浓度。硝酸根离子的扩散梯度从根毛中流出，进入土壤。但是根毛细胞仍然能够通过主动运输吸收硝酸根离子。 Active transport 主动运输 Cells can use energy to make substances move across their membranes, up the concentration gradient. This process is called active transport. 细胞可以利用能量使物质穿过其膜，沿着浓度梯度向上移动。此过程称为主动传输。

37. There are special carrier proteins in the cell membrane of the root hair cells. These proteins pick up nitrate ions from outside the cell, and then change shape so that they push the nitrate ions through the cell membrane and into the cytoplasm of the cell. Energy – provided by the mitochondria, which carry out aerobic respiration – is needed to produce the shape change in the carrier protein. 根毛细胞的细胞膜中有特殊的载体蛋白。这些蛋白质从细胞外吸收硝酸根离子，然后改变形状，使硝酸根离子穿过细胞膜进入细胞质。能量 - 由线粒体提供，线粒体进行有氧呼吸 - 需要产生载体蛋白的形状变化。 Active transport 主动运输

38. Active and passive transport are the two main biological process which plays an important role in supplying nutrients, water, oxygen, and other essential molecules to cells and also by removing waste products. 主动和被动运输是两个主要的生物过程，在向细胞提供营养、水、氧和其他必需分子以及清除废物方面发挥着重要作用。 Active and passive transport

39. Both active and passive transport works for the same cause, but with different movement. 主动和被动运输都用于相同的原因，但运动方式不同。 Active transport requires chemical energy because it is the movement of biochemicals from areas of lower concentration to areas of higher concentration. 主动运输需要化学能，因为它是生化物质从低浓度区域向高浓度区域的运动。

40. On the other hand, passive transport moves biochemicals from areas of high concentration to areas of low concentration; so, it does not require energy. 另一方面，被动运输将生化物质从高浓度区域转移到低浓度区域 ; 因此，它不需要能量。

41. Thank you