B1 - Cell Structure and Transport (Y10 - Spring 1)

Question 1

🟢 How do you Calculate the Actual Size and Image Size of a Specimen and also the Magnification?

(Equation and Triangle)

Answer 1

Magnification = Image Size / Actual Size of Specimen

In a Triangle I is at the top, A and M are on the bottom, which creates an ‘I AM’ triangle.

Question 2

🟢 Parts of the Microscope:

Answer 2

• Eyepiece -Fine Focus
• Objective Lens -Coarse Focus
• Stage -Fine Focus
• Slide -Light

Question 3

🟢 Why was the invention of the Electron Microscope so important?

Answer 3

The invention of the electron microscope in the 1930’s allowed biologists to see and understand more about the subcellular structures inside of cells. These instruments use a beam of electrons to form an image and can magnify objects up to around 2 million times. Transmission electron microscopes give 2D images with very high magnification and resolution. Scanning electron microscopes give dramatic 3D images but lower magnifications. (These electron microscopes are very expensive and have to be kept in special temperature, pressure and humidity-controlled rooms).

Question 4

🟢 How Do You Calculate Magnification?

Answer 4

With a light microscope, you multiply the magnification of the eyepiece lens by the magnification of the objective lens. So if your eyepiece lens is X4, and your objective lens is X10, then you do:

e.g: 4 (Eyepiece Lens) x 10 (Objective Lens) = 40 (Overall Magnification)

Question 5

🟢 What is Magnification and Resolving Power

Answer 5

There is a minimum distance between two objects to be able to see them as two seperate things; if they are closer than this, they will appear as one object. Resolution is the ability to distinguish between two seperate points and it is the resolving power of a microscope that affects how much detail it can show. A light microscope has a resolving power of about 200nm, a scanning electron microscope of about 10nm and a transmission elelctron microscope of about 0.2nm (that is approximatly the distance apart of two atoms in a sold substance).

Question 6

🟢 Resolving Power Definition

Answer 6

Resolving Power is measured by its ability to differentiate two lines or points in an object, essentially, being able to tell two seperate cells, or whatever else is being looked at apart.

Question 7

🟢 What is found in the Structure of an Animal Cell?

Answer 7

• Cell Membrane
• Cytoplasm
• Ribosomes
• Mitochondria
• Nucleus

Question 8

🟢 What is found in the Structure of an Plant Cell?

Answer 8

• Cell Membrane
• Cytoplasm
• Ribosomes
• Mitochondria
• Nucleus
• Large Permnent Vacuole
• Chloroplasts

Question 9

🟢 Nucleus Definition

Answer 9

Controls all the activities of the cell and is surrounded by the nuclear membrane. It contains the genes on the chromosomes that carry the instructions for making the peotiens needed to build new cells or new organisms. The average diameter is around 10µm.

Question 10

🟢 Cytoplasm Definition

Answer 10

A liquid gel in which the organelles are suspended and where most of the chemical reactions needed for life.

Question 11

🟢 Cell Membrane Definition

Answer 11

Controls the passage of substances such as glucose and mineral ions into the cell. It also controls the movement ions into the cell. It also controls the movement of substances such as urea or hormones out of the cell.

Question 12

🟢 Mitochondria Definition

Answer 12

Structures in the cytoplasm where aerobic respiration takes the place, releasing energy for the cell. They are very small, around 1µm - 2µm in length and only 0.2-0.7µm in the diameter.

Question 13

🟢 Ribosome Definition

Answer 13

This is where protein synthesis takes place, making all the proteins need in the cell.

Question 14

🟢 Chloroplast Definition

Answer 14

These are found in tne green parts of a plant. They are green because they contain a substance called chlorophyll, which abosorbs light so the plant can make food photosynthesis. Each chloroplast is around 3-5µm long. (Root cells do not have chloroplasts because they do not photosynthesise.

Question 15

🟢 Large Permanent Vacuole Definition

Answer 15

This is a space in the cytoplasm filled with cell sap. This is important for keeping the cells rigid to support the plant.

Question 16

🟢 What are Eukaryotic Cells?

Answer 16

Eukaryotic Cells are examples of plant and animal cells. Eukaryotic Cells all have a cell membrane, cytoplasm, and genetic matrial that is enclosed in a nucleus. The genetic material is a chemical called DNA and this forms structures called chromosomes that are contained within the nucleus. All animals (including humnan beings), plants, fungi and protista are Eurkaryotes.

Question 17

🟢 What are Prokaryotic Cells?

Answer 17

Bacteria are single-celles living organisms. They are examples of prokaryotes. At 0.2 - 2µm in length, prokaryotes are 1-2 orders magnitude smaller than Eukaryotes, meaning you could hundreds of thousands of bacteria onto something such as this full stop. Because of this, you cannot se individual bacteria without a very powerful microscope. When you cluture bacteria on an agar p,ate, you grow many millions of bacteria. This enables you to see the bacterial colony with your naked eye.

Bacteria have cytoplasm and a cell membrane surrounded by a cell wall, but the cell wall does not contian the cellulose you see in plant cells. In prokaryotic cells the genetic material is not encolsed in a nucleus. The bacterial chromosome is a single DNA loop found free in the cytoplasm. Prokayotic cells may also contain extra small rings of DNA called plasmids. Plasmids code for very specific features such as antibiotic resistance.

Question 18

🟢 Adaptations on the Bacteria and how it can be Good/Bad

Answer 18

Some of the bacteria have protective slime capsules around the outside of the cell wall. Some types of bacterium have at least one flagellum (that is a long protein strand that lashes about). These bacteria use their flagella to move themselves around. Many bacteria have little/no affect on organisms but many of them can be very useful despite this. On the other hand, some bactria can be harmful, as they can cause diseases in humans and other animals as well as the fact that they can also decompose and destroy stored food.

Question 19

🟢 What Came First: Eurkaryotic or Prokaryotic Cell?

Answer 19

This idea of Prokaryotic Cells existing before Eukaryotic Cells is a reasonable idea, and also links in with the theory of how the Earth has evolved and grown since the Universe’s existence. Points to back this fact up are that Eukaryotic Cells are a lot more complex than Prokaryotic Cells, meaning that they could be an evolved version of Prokaryotes. Also, there is a lot less variation in the Prokaryotic Cells, so think could also point towards it being older and less expansive and different. A third point and reason is that Eukaryotic Cells can come from Animals, Plants, Protist and Fungi, which were all developed later on in the evolution of Earth, meaning the Prokaryotic Cells could’ve been able to exist before them.

The first ever Eukaryotic Cells are though to have evolved around 2 billion years ago, whilst Prokaryotic Cells are though to have evolved 3.5 billion years ago. From, this I have also found out that the evolution of the Eukaryotic Cell is explained by the endosymbiotic theory, and that the Prokaryotic Cell were in existence about 1 billion years after the formation of the Earth’s crust, but only appeared in the fossil records later on.

Question 20

🟢 How is Bacteria Different to Plant and Animal Cells?

Answer 20

Bacteria is different to Animal and Plant Cells in the way that it is structured and they way it reproduces and spreads. For example, Bacteria cells do not have a nucleus meaning their DNA is free-flowing unlike Plant and Animal cells. Also, some types of Bacterium have at least one flagellum, in which Plant and Animals cells always have none.

Question 21

🟢 Differences between Prokaryotic Cells and Eukaryotic Cells?

Answer 21

Prokaryotic Cells:
- Prokaryotic Cells are less complex
- Prokaryotic Cells tend to usually be a lot smaller in size than Eukaryotic Cells
- Prokaryotic Cells have no Nucleus, meaning that they have free-floating DNA!
- Prokaryotic Cells have no Membrane-Bound Organelles.
Membrane-Bound Organelles have their own Nucleus, Mitochondria, Endoplasmic Reticulum and Golgi Apparatus.

Eurkaryotic Cells:

• Eukaryotic Cells are more complex
• Eukaryotic Cells tend to usually be a lot larger in size than Prokaryotic Cells
• Eukaryotic Cells have a Nucleus in which they store all of their DNA that it needed.
• Eukaryotic Cells have Membrane-Bound Organelles
• Eukaryotic Cells can be found in Protists, Plants, Animals and Fungi. This means there is more variations in them, so plant cells can contain chloroplasts, while animals cells will not.

Question 22

🟢 How is Bacteria Different to Plant and Animal Cells?

Answer 22

Bacteria is different to Animal and Plant Cells in the way that it is structured and they way it reproduces and spreads. For example, Bacteria cells do not have a nucleus meaning their DNA is free-flowing unlike Plant and Animal cells. Also, some types of Bacterium have at least one flagellum, in which Plant and Animals cells always have none.

Question 23

🟢 How to remember if the Eurkaryotic or Prokaryotic cell came before the nucleus?

Answer 23

Eukaryotic Cells (exist after a true nucleus)

and

Prokaryotic Cells (exist before a true nucleus)

Question 24

🟢 (Animal Specialised Cells) Nerve (Neurone) Cells Fuctions and Specialisations/Adaptions

Answer 24

Nerve cells are specialised to carry electrical impluses around the body of an animal. They provide a rapid communication system between the different parts of the body. They have serveral adaptions including:

• Lots of dendrites to make connections to other nerve cells
• An axon that carries the nerve impulse from one place to another. An axon can be very long (the axon in a blue whale can be up to 25m long!)
• The nerve endings or synapses are adapted to pass the impluses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals. They contain lots of mitochondria to provide he energy needed to make transmitter chemicals.

Question 25

🟢 (Animal Specialised Cells) Muscle Cells Fuctions and Specialisations/Adaptions

Answer 25

Muscle cells are specialised cells that can contract and relax. Striated
(striped) muslce cells work together in tissues called muscles. Muscles contract and relax in pairs to move the bones of the skeleton, so vertebrates can move on lands and in water, and in some cases fly. Smooth muscle cells form one of the layers of tissue in your digestive system and they contract to squeeze the food through your gut. Striated muscle cells have three main adaptions:

• They contain special proteims that slide over each other making the fivres contract
• They contain many mitochondria to transfer the energy needed for the chemical reactions that take place as the cells contract and relax.
• They can store glycogen, a chemical that can be broken doen and used in cellular respiration by the mitochondria to transfer the energy needed for the fibres to contract.

Question 26

🟢 (Animal Specialised Cells) Sperm Cells Fuctions and Specialisations/Adaptions

Answer 26

Sperm cells are usually released a long way from the egg they’re going to fertilise. Dependning on the type of animal, sperm cells need to move through water of the female reproductive system to reach an egg. Then they have to break into this egg. Sperm cells have serveral adaptations to make all of these things possible:

• A long tail whips from side to side to help move the sperm through water or the female reproductive system
• The middle section is full of mitochondria, which transfer the energy needed for the tail to work.
• The arcosome stores digestive enzymes for breaking down the outer layers of the egg.
• A large nucleus contains the gentic information to be passed on.

Question 27

🟢 (Plant Specialised Cells) Root Hair Cells Fuctions and Specialisations/Adaptions

Answer 27

You find root hair cells close to the tips of growing roots. Plants need to take in lots of water (and dissolved mineral ions). The root hair cells help the, to take up water and mineral ions more efficiently. Root hair cells are always relativly close to the xylem tissue, which carries water and mineral ions up into the rest of the plant. Mineral ions are moved into the root hair cell by active transport. Root hair cells have three main adaptions:

-They greatly increase the surface area avaliable for water to move into the cell.
-They have a large vacuole that speeds up the movement
of water by osmosis from the soil across the root hair cell
-They have many mitochondria

Question 28

🟢 (Plant Specialised Cells) Photosynthetic Cells Fuctions and Specialisations/Adaptions

Answer 28

One of the ways plants differ from animals is that plants can make their own food by photosynthesis. There are lots of plant cells that can carry out photosynthesis. There are lots of plant cells that can carry out photosynthesis - and lots that cannot. Photosynthic cells usually have a number of adaptions including:

-They can contain specialsed green structures called chloroplasts containing chlorophyll that trap the light needed for photosynthesis.
-They are usually positioned in comtinuous layers in the leaves
and outer layers of the stem of a plant so they can absorb as
much light as possible.
-They have a large permanent vacuole that helps keep the cell
rigid as a result of osmosis. When lots of these rigid cells are
arranged together to form photosynthetic tissue they help
support the stem. They also keep the leaf spread out so it can
capture as much light as possible.

Question 29

🟢 (Plant Specialised Cells) Xylem Cells Fuctions and Specialisations/Adaptions

Answer 29

Xylem is the transport tissue in plants that carries water and mineral ions from the roots to the highest leaves and shoots. The xylem is also important in supporting the plant. The xylem is made up of xylem cells that are adapted to their functions in two main ways:

-The xylem cells are alive when they are first formed but a
special chemical called lignin builds up in spirals in the cell
walls. The cells die and form long hollow tubes that allow water
and mineral ions to move easily through them, from one end of
the plant to another.
-The spirals and rings of lignin in the xylem cells make them very
strong and help them withstand the pressure of water moving up the plant. They also support the plant stem

Question 30

🟢 (Plant Specialised Cells) Phloem Cells Fuctions and Specialisations/Adaptions

Answer 30

Phloem is the specialised transport tissue that carries the food made by photosynthesis around the body of the plant. It is made up of phloem cells that form tubes rather like xylem cells, but phloem cells do not become lignified and die. The dissolved food can move up and down the phloem tubes to where it is needed. The adaptions of the phloem cells include:

-The cell walls between the cells break down to form special
sieve plates. These allow water carrying dissolved food to
move freely up and down the tubes to where it is
needed
-Phloem cells lose a lot of their internal structures but they
are supported by companion cells that help to keep them
alive. The mitochondria of the companion cells transfer the
energy needed to move dissolved food up and down the plant in phloem.

Question 31

🟢 What Is Diffusion

Answer 31

Diffusion is the spreading out of particles from an area of high concentration to an area of low concentration. Diffusion is the spreading out of the particles of gas, or of any substance in solution (a solute). This results in the net movement (overall movement) of particles. The net movement is from an area of higher concentration to an area of lower concentration of the particle. It takes place because of the random movement of the particles (molecules or ions). The motion of the particles causes them to bump into each other, and this moves them all around. (Diffusion is a Passive movement of particles, meaning it expends/uses no energy).

Question 32

🟢 How Can Diffusion Rates be affected?

Answer 32

When there is a big difference in concentration between
two areas, diffusion will take place quickly. Many particles will move randomly towards the area of low concentration, with relativly few moving in the other direction. On the other hand, if there is only a small difference in concentrations, then the net movement will be quite slow. The equation for the net movement is:

Net Movement = Particles Moving In - Particles Moving Out

The general rule is greater the difference in concentration, the faster the rate of diffusion will be, so the steeper the concentration gradieng, the faster the rate of diffusion (the concentration gradient is the difference between the two areas of concentration). You can also speed up the rate of diffusion by raising the temperature. An increase in temperature ,eams the particles in a gas or a so,ution move around move quickly, due to kietic energy, resulting in the diffusion to take place more rapidly.

Question 33

🟢 Examples of Diffusion

Answer 33

Dissolved substances move in and out of your cells by diffusion across the cell membrane. The substances include simple sugars, such as glucose, gases such as oxygen and carbon dioxide, and waste products such as urea from the breakdown of amino acids in your liver. Urea passes from liver cells into blood plasma by diffusion and is excreted by the kidneys.

The oxygen used for respiration passes from the air in your lungs into your red blood cells through the membranes by diffusion. The oxygen moves down a concentration gradieng from a region of high oxygen concentration to a region of low oxygen concentration. This more specifically can take place in the alveoli, where the CO2 diffuses out of the blood with the Oxygen diffusing into the blood. Here, carbon dioxide moves out of the body cells into the red blood cells and then into the air in the lungs by diffusion down a concentration gradient in a similar way. The diffusion of oxygen and carbon dioxide in opposite directions in the lungs is known as gas exchange.

Also, individual cells can be adapted to make diffusion easier and even more rapid. The most common adaptation is to increase the surface area of the cell membrane. By folding up the membrane if a cell, or the tissue lining an organ, the area over which diffusion can take place is greatly increased. Therefire, the rate kf diffusion is also greatly increased, so that much more of a substance moves in a given time.

An example of this increase in surface area is from intestinal cells.

Question 34

🟢 How Are Substances Moved By Active Transport?

Answer 34

Active transport allows cells to move substances from an area of low concentration to an area of high concentration. This movement is against the concentration gradient. As a result, cells can absorb ions from very dilute solutions. It also enables cells to move substances, such as sugars and ions, from one place to another through the cell membrane.

Energy is needed for the active transport system to carry a molecule across the mebrane and then return to it’s orginal position. This energy is produced during cell respiration. Scientists have shown in a number if different cells that the rate of respiration and the rate of active transport are closely linked. In other words, if a cell respires and releases a lot of energy, it can carry out lots of active transport. Active Transport is an ‘Active’ process, meaning energy is used and expended to move the cells.

Question 35

🟢 Why Is Active Transport Important?

Answer 35

Active Transport is widely used in cells, and there are some situations where it is especially important, for example, mineral ions in the soil, such a nitrate ions, are usually found in very dulute solutions. These solutions are more dilute than the solution within the plant root hair cells. By using active transport, plants can absorb these mineral ions, even though it is against the concentration gradient. (Because there are a higher concentration of mineral ions inside the root hair cell, than there are in the soil.) The mineral ion is able to pass through the cell membrane, as it is latched onto by a protein in the cell membrane and is then turned and passed into the inside of the cell membrane, therefore going against the concentration gradient, which is exactly why this is an ‘Active’ process, because this is where the energy is expended.

Sugar such as glucose is always activly
absorbed out of your gut and kidney
tubules into your blood. This is often done against a large concentration gradient. For example, glucose is needed for cell respiration, so it is important to get as much as possible out of the gut. This concentration of glucose in your blood is kept steady, so sometimes it is higher than the concentration if glucose in your gut. When this happens, active transport is used to move glucose from your gut into your blood against the concentration gradient.

Question 36

🟢 Why is Surface Area to Volume Ratio Important?

Answer 36

The surface area to volume ratio is important in biology. It makes a big difference to the way animals can exchange substances with the environment. Surface area to volume ratio is also important when you consider how energy is transferred by living organisms, and how water evaporates from the surfaces of plants and animals.

Question 37

🟢 What is Surface Area to Volume Ratio

Answer 37

The ratio of surface area to volume falls as objects get bigger. You can see this clearly in Figure 1. In a small object, the surface area to volume (SA:V) ratio is relatively large. This means that the diffusion distances are short and that simple diffuion is sufficient for the exchange of materials.

As organsisms get bigger, the surface area to volume ratio falls. As
the distances between the centre of the organism and the surface
get bigger, simple diffusion is no longer enough to exchange
materials between the cells and the environment

Question 38

🟢 What happens to the Surface Area to Volume Ratio as an Organism gets bigger?

Answer 38

As living organisms get bigger and more complex, their surface area
to volume ratio gets smaller. This makes it increasingly difficult to
exchange matrials quickly enough with the outside world:

• Gases and food molecules can no longer reach every cell inside the organism by simple diffusion.
• Metabolic waste cannot be removed fast enough to avoid poisoning the cells.

In many larger organisms, there are special surfaces where the exchange of materials takes place. These surfaces are adapted to be as effective as possible. You can find them in humans, un other animals, and in plants.

Question 39

🟢 The Adaptations For Exchanging Materials

Answer 39

There are various adaptations to make the process of exchange more efficient. The effectiveness of an exchange surface can be increased by:

• Having a large surface area of which exchange can take place.
• Having a thin membrsne or being thun to provide a shirt diffusion path.
• In animals, having an efficient blood supply moves the diffusing substances away from the exchange surfaces and maintakns a steep concentration (diffusion) gradient.
• In animals, being ventilated makes gas exchnage more efficient by maintaining steep concentration gradients.

Question 40

🟢 Osmosis Definition

Answer 40

Osmosis is the movement of water molecules through a partially permeable membrane, e.g cell membrane.

Question 41

🟢 What 2 Types Of Solutions Are There and How Water Is Affected In Them

Answer 41

Partially permeable membranes let water move across them. Remember:

• A dilute solution of sugar contains a high concentration of water (the solvent). It has a low concentration of sugar (the solute)
• A concentrated sugar solution contains a relatively low concentration of water and a high concentration of sugar.

Question 42

🟢 What is Osmosis and How Does It Work

Answer 42

The cytoplasm of a cell is made up of chemicals dissolved in water inside a partially permeable cell membrane. The cytoplasm contains a fairly concentrated solution of salts and sugars. Water moves from a dilute solution (with a high concentration of water molecules) to a concentrated solution (with fewer water molecules in a given volume) across the membrane of the cell.

This is a special type of diffusion, where only water moves across a partially permeable membrane from a dilute solution to a concetrated solution is called osmosis.

Question 43

🟢 How Can Concentration Affect Osmosis

Answer 43

The concentration if solutes inside your bodycells needs to stay at the same level for them to work properly. However, the concentration of the solutions outside your cells may be very different to the concentration inside of them. This concentration gradient can cause water to move into or out of the cells by osmosis.

• If the concentration of solutes in the solution outside the cell is the same as the internal concentration, the solution is isotonic to the cell.
• If the concentration of the solutes in the solution outside the cell is higher than the internal concentration, the solution is hypertonic to the cell.
• If the concentration of solutes in the solution outside the cell is lower than the internal concentration, the solution is hypotonic to the cell.

Question 44

🟢 How Does Osmosis Work In Animals And What Problems Can Arise?

Answer 44

If a cell uses up more water in its chemical reactions, the cytoplasm becomes more concetrated. The surrounding fluid become hypotonic to the cell and more water immidatley moves in by osmosis.

If the cytoplasm becomes too dilute becuase more water is made in chemical reactions, the surrouding fluid becomes hypertonic to the cell and water leaves the cell by osmosis. Osmosis restores the balance in both cases.

Question 45

🟢 How Can You Use Plants To Measure Osmosis

Answer 45

Plant tissue reacts so strongly to the concentration of the external solution that you can use it as an osmometer - a way of measuring osmosis. There are lots of ways you can investigate the effect of osmosis on plant tissue, each with advantages and disadvantages.

The basis of many experiments is to put plant tissue into different concentrations of salt solutions or sugar solutions. If a plant tissue is placed in a hypotonic solution, water will move out by osmosis. These changes can be measured by the effect they have on the tissue sample.

Measuring changes in mass is a widely used method for investigating the uptake or loss of water from plant toddues by osmosis. You musy take care not to include any liquid left on the outside of the plant tissue in your measurements as this can have a big effect on your results.

Question 46

🟢 Describe and Explain how Osmosis can affect eggs when put in a 5% Sugar Solution, a 30% Sugar Solution, and a Fully Saturated Sugar Solution

Answer 46

Overtime, it is pretty evident that the more dilute the liquid surrounding the egg, the more the egg will increase in size, gaining water. On the other hand, if the egg is surrounded by liquid that is quite concentrated, then it will shrivel up and decrease in size, losing water.

For the 5% sugar solution for example, the water molecules will move from the more dilute water solution (more water in the solution), into the more concentrated egg (less water in the egg), through it’s partially permeable membrane, via the process of osmosis. This will cause the egg to increase in size/volume over time.

For the saturated solution, for example, the water molecules will move from the more dilute egg (more water in the egg), to the more concentrated sugar solution (less water in the solution), through the egg’s partially permeable membrane, via the process of osmosis. This will cause the egg to shrink and shrivel up in size and decrease in volume.

For a 30% solution for example (or one that is equal in concentration to the egg), there may be no net osmosis, however, that does not mean that there is no osmosis at all, as water molecules will still move between the partially permeable membrane, but overall there will not be a change in the concentration of the egg by the end.

Question 47

🟢 How can Red Blood Cells for example, be affected/damaged by osmosis

Answer 47

Osmosis can also cause big problems. If the solution outside the cell becomes much more dilute (hypotonic) than the cell contents, water will move by osmosis. The cell will swell and may burst (undergo lysis). If the solution outside the cell becomes much more concentrated (hypertonic) than the cell contents, water will move out the cell by osmosis. The cytoplasm will become too concentrated and the cell wil shrivel up (crenate) and can no longer survive. Once you understand the effect osmosis can have on cells, the importance of maintaining constant internal conditions becomes clear.

Question 48

🟢 What happens when water moves into plant cells by osmosis

Answer 48

Plants rely on osmosis to support their stems and leaves. Water moves into plant cells by osmosis. This causes the vacuole to swell, which presses the cytoplasm against the plant cell wall. The pressure builds up until no more water can physically enter the cell - this pressure is known as turgor. Turgor pressure makes the cells hard and ridged, which in turn keeps the leaves and stems of the plant rigid and firm.

Question 48

🟢 What happens when the concentration of solution surrounding plants changes from hypotonic (less concentrated) to hypertonic (more cencentrated)

Answer 48

Plants need the fluid surrounding the cells to always be hypotonic to the cytoplasm, with a lower concentration of solutes and a higher concentration of water than the plant cells themselves. This keeps water moving by osmosis in the right direction and the cells are turgid. If the solution surrounding the plant cells in hypertonic to (more concentrated than) the cell contents, water will leave the cells by osmosis. The cells will no longer be firm and swollen - they become flaccid (soft) as there is no pressure on the cell walls. At this point, the plants wilts as turgor no longer supports the plant tissues.

Question 49

🟢 What happens when water starts to be lost by plants by osmosis (+ What is plasmolysis)

Answer 49

If more water is lost by osmosis, the vacuole and cytoplasm shrink, and eventually the cell membrane pulls away from the cell wall. This is plasmolysis. Plasmolysis is usually only seen in laboratory experiments. Plasmolysed cells die quickly unless the is osmotic balance is restored.