AP State Syllabus 9th Class Biology Important Questions 4th Lesson Movement of Materials Across the Cell Membrane
9th Class Biology 4th Lesson Movement of Materials Across the Cell Membrane 1 Mark Important Questions and Answers
What is exosmosis?
The process in which water molecules leave the cell is called exosmosis.
What is endosmosis?
The process in which water molecules enter the cell is called endosmosis.
Who are the scientists that removed salt from sea water and how?
Freddie Mercury and David Bowie removed salt from sea water by using a semi permeable membrane by a process called desalination.
What happens if red blood cells are placed in distilled water?
The red blood cells placed in hypotonic solution like distilled water the cells swell and burst.
What is the better food during a journey?
The natural fruits with 80% to 90% water in them, not only quench our thirst but also reduce our hunger.
What is a saturated solution?
The solution that cannot takeup more solute to dissolve is called a saturated solution.
Name the principle involved in dialysis and reverse osmosis.
Name the principle involved in air freshners, mosquito repellents that are used in our daily life.
What is a hypotonic solution?
If the medium surrounding the cells has a higher water concentration than the cell, the cell will gain water by osmosis. Such type of solution is called hypotonic solution.
What is isotonic solution?
If the medium has exactly the same concentration as the cell there will be no net movement of water across the cell membrane. Such solution is called isotonic solution.
What is hypertonic solution?
If the medium has a lower water concentration, then the cell will loose water by osmosis. Such a solution is called hypertonic solution.
What is plasmolysis?
When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.
How do substances like CO2 and water move in and out of the cell?
CO2 moves by diffusion and water moves by osmosis through cell membrane.
What will happen to the size of the cell if it is placed in hypotonic solution?
When the cell is placed in hypotonic solution, water enters into the cell. Hence, the cell swell up.
What will happen to the size of the cell if it is placed in hypertonic solution?
Water leaves from the cell when we keep the cell in the hypertonic solution. Hence the swell will shrink.
Why does the skin of your finger shrinks when you wash your clothes for a long time?
A soap solution is a hypertonic solution. So, water moves out of your fingers by osmosis.
A person takes concentrated solution of salt. After sometime, he starts vomiting. What is the phenomenon responsible for such solution?
Exosmosis in intestine causes dehydration.
When you are cooking vegetables generally you add salt to vegetables during cooking. After adding salt, vegetables release water. What mechanism is responsible for this?
Exosmosis is responsible for the above mechanism.
9th Class Biology 4th Lesson Movement of Materials Across the Cell Membrane 2 Marks Important Questions and Answers
What is reverse osmosis ? What are its applications?
1) When heavy pressure is applied on salt solution which is separated from fresh water with semipermeable membrane, the water moves from salt solution into fresh water leaving the salt behind.
2) This process is known as reverse osmosis.
Home reverse osmosis machines are available in the market, which filter salt water through three membranes.
What is diffusion? Give example.
The process by which some materials when kept in a medium like air and water spread equally throughout it, it is called diffusion.
If a bottle of scent is opened in one corner of a room, the smell spreads in the entire room due to the diffusion of scent molecules.
What is Graham’s law?
- Thomas Graham, Scottish physical chemist, worked on diffusion of gases.
- He had infered that a more soluble substance in a medium diffuse faster than a less soluble substance.
- This is popularly known as Graham’s law.
What is dialysis? Who constructed dialysis machine? The machine works on which principle?
- Dialysis is the artificial method of removal of wastes from the blood.
- Dr. William Kolff a Dutch physician in the year 1947 constructed dialysis machine.
- Dialysis machine works on principle of diffusion and filtration across a semi permeable membrane.
Why did we feel thirstier, after eating 50 gms of potato chips in journey?
- After eating foods preserved like potato chips we feel thirstier because water is drawn from the body into the digestive system to maintain water balance.
- So we have to drink more water after eating salty food.
Why does CO2 can not enter the cell?
- This is due to diffusion of CO2 from the cell into the blood through semipermeable membrane or cell membrane.
- Due to respiration concentration of CO<sub>2</sub> increases in the cell than outside.
- Hence CO2 diffuses out.
Water enters the root cells from the soil, why? Name the process involved in this.
Water enters the plant through root hairs, because the concentration of water in the soil arounds the roots is higher than that inside the root epidermis. This process is called osmosis.
Why do dry apricots placed in salt solution do not swell while they do so when kept in water?
Dry apricots swell up in water because their cells have a high osmotic concentration which causes passage of water into them. They do not swell up when placed in salt solution because the external solution is hypertonic.
What happens if plasma membrane ruptures or breaks?
If the plasma membrane ruptures or breaks down, the following may happen.
a) The cell will lose its shape.
b) Since plasma membrane is selectively permeable.
If it breaks all the useful substances also move out of the cell, all the metabolic activities of the cell will get effected and the cell may die.
What happens to the dry raisins when we put them in plain water for sometime? What happens if these raisins are now placed in concentrated solution?
i) When we put dry raisins in plain water, they gain water and the size of dry raisins will increase.
ii) When these swollen raisins are placed in concentrated salt solution, these loose water and shrink.
9th Class Biology 4th Lesson Movement of Materials Across the Cell Membrane 4 Marks Important Questions and Answers
What are the differences between diffusion and osmosis?
|1. Substance move from area of high concentration to area of low concentration.||Water moves from area of low concentration to area of higher concentration.|
|2. Semipermeable membrane is not necessary.||Semipermeable membrane is necessary.|
|3. Diffusion can takes place in solids, liquids and gases.||Osmosis occurs in liquid medium.|
|4. It is a physical process.||It is a physical, physiological process.|
What is osmosis? Explain with example.
The flow of water from a region of dilute solution to a more concentrated one through a semipermeable membrane.
Eg : Osmosis with kishmish / raisin.
- Dried kishmish are put in pure water and left for some time. Then these kishmish are placed in concentrated solution of sugar or salt.
- It is proved experimentally that kishmish gains water and swells and when placed in concentrated solution the kishmish loose water and shrink.
- In the above two situations water moved from low concentration to higher concen-tration due to osmosis.
What is cell membrane? What are its functions?
The outermost, extremely delicate elastic membranous covering of the cell that separate its contents from the external environment is called plasma membrane.
Functions of plasma membrane :
1. Shape :
Plasma membrane provides a definite shape to semi-fluid contents of the cell.
2. Mechanical barrier :
It functions as mechanical barrier that protects the internal contents of the cell,
3. Selectively permeable :
Plasma membrane determines what substances are to be allowed entry or exit from the cell.
4. Endocytosis :
It helps the cell to engulf food and other substances from its external environment by endocytosis.
5. Recognition :
The recognition centres of plasma membrane help in tissue formation, distinction of foreign substances and defense against microbes.
6. Flow of information :
Plasma membrane provides flow of information amongst different cells of the same organism.
7. Osmosis :
Osmosis occurs due to presence of tiny water channels in the plasma membrane.
8. Cell continuity :
At places plasma membrane of adjacent cells become continuous to form plasmodesmata and cell junctions.
9. Specialization :
Plasma membrane gets modified to perform different functions.
E.g. : absorption in microvilli.
Importance of osmosis to living organisms.
- Water enters into roots through osmosis.
- Water moves between the cells through osmosis.
- Osmosis helps in opening and closing of stomata.
- It bring about movement of water and minerals in certain plants.
- In our body waste materials are filtered from blood.
- In our body useful materials are absorbed along with water through osmosis.
Explain the process of reverse osmosis with a neat labelled diagram.
When salt water is separated from fresh water through a semi-permeable membrane, the filteration can be achieved by applying high pressure on salt water. Due to this pressure water moves from salt solution into fresh water leaving the salt behind. This phenomenon is widely used nowadays in water purifiers to filter salt water.
9th Class Biology 4th Lesson Movement of Materials Across the Cell Membrane Important Questions and Answers
What will happen if we keep deshelled raw egg in salt water?
i) Salt water is more concentrated than egg Yolk.
ii) When raw de-shelled egg placed in salt water, water from egg comes out through egg membrane. This called exosmosis.
iii) Due to exosmosis, the size of the egg decreases.
i) Pour sugar solution in the potato cup upto a level as shown by the pin in the figure.
ii) Keep the potato cup in the bowl filled with water upto half the height of the potato cup.
Answer the following questions based on the above experiment
i) What is the aim of the experiment?
ii) What will be the observation in this experiment?
iii) If the potato cup is filled with water and the beaker is filled with sugar solution, what will be the observation?
iv) What is the difference between this experiment when compared with dried grapes (kishmish) kept in water?
i) To prove osmosis in potato living cells.
ii) Sugar solution level rises in potato cup beyond the point where needle placed.
iii) Sugar solution level falls down in potato cup.
iv) In both experiments endosmosis is observed in the cells.
Latha dropped some crystals of KMnO<sub>4</sub> in a beaker of water and observing to know what happens. What is the phenomenon that occurs in the experiment?
Read and complete the following table according to the given information.
|Process / Function||Name of the Phenomenon|
|1. Plasma membrane determines what substances are to be allowed entry or exit from the cell.|
|2. The flexibility of membrane to engulf food and other substances.|
|3. Movements of water through tiny channels of plasma membrane (from lower concentration to higher concentration.)|
|4. Movement of molecules / substances from higher concentration to lower concentration.|
- Selective permeability
Observe the following substances and answer the following questions.
|Substance||Should go into the cell||Should go out of the cell|
a) Which substances should go into the cell?
b) Which substances should go out the cell?
c) Which is useful to transport the substances into the cell?
d) What is use of osmosis?
a) Oxygen, Glucose, Proteins, Fats, Vitamins.
b) Carbondioxide, Waste materials.
c) Plasma membrane.
d) Plasma membrane is a selectively permeable membrane. It allows entry of useful certain materials exit of some unuseful substances while preventing passage to remaining substances.
It helps in keeping the ceil alive.
Observe the diagram answer the following questions.
a) Which chemical material is used to made a semi permeable membrane from an egg?
b) Which precautions do you take to make a semipermeable membrane?
a) Dilute Hydrochloric Acid.
b) 1) Keep the raw eggs in dil HCl for 4 to 5 hours.
2) Wash the eggs under tap water.
3) Carefully pierce a pencil sized hole in the egg membrane and drain the contents.
4) Again wash the membrane with fresh water.
Two beakers, funnel, filter paper, retort stand, sugar, dye and wheat or rice flour and plastic bottle would be given to you. What experiment will you do with this? Write the procedure and precautions of that experiment.
- Arrange the filtering apparatus as shown in the figure.
- Prepare wheat or rice powder solution in a beaker by adding one tea spoon of powder in 100 ml of water.
- Add a drop of tincture iodine to the solution.
- Now pour the solution into the funnel.
- Filter paper allows water and dissolved rice powder to pass through it.
- Filter paper does not allow the undissolved powder precipitate through it.
- Ensure that the using filter paper should not have any damage or holes.
- Stir the powder solution continuously, while pouring it slowly through filter paper.
What happens if cells are not permeable
If cells are not permeable, they will not get the useful substances like minerals, water, nutrients and oxygen. Like this way, the waste products released during cellular activities will not be sent out. As a result the cell may die.
Rajesh conducted an experiment to know the movement of substances using potato and sugar solution.
a) What is the objective of Rajesh’s experiment?
b) Write the materials required by Rajesh to conduct this experiment.
c) Where does the level of solution increase?
d) What is your observation in this experiment?
a) To observe osmosis
b) One raw potato, one boiled potato, two beakers, bowls, two pins, water, sharp knife.
c) Increase in the level of sugar solution in potato.
d) Water always moves towards the sugar solution the movement of water from less concentration to high concentration through a membrane is called osmosis.
Give some examples for process that occurs through permeable membrane that you observed in your daily life.
Ex : 1. Water moves from one cell to another through osmosis.
Ex : 2. Movement of water from soil to roots.
Ex : 3. Waste materials in our blood are filtered.