1. Three strips labelled W, X and Y are cut from a herbaceous plant. The strips are then immersed in sucrose solutions of different concentrations and in distilled water. Diagram 6 shows the condition of each strip after being immersed for 30 minutes in each solution.Tiga jalur berlabel W, X, dan Y dipotong dari satu pokok renek. Jalur itu kemudiannya direndam di dalam larutan sukrosa yang berlainan kepekatan dan di dalam air suling. Rajah 6 menunjukkan keadaan setiap jalur selepas 30 minit direndam di dalam setiap larutan.

 

 DIAGRAM/RAJAH 

 (a) Explain what happens to each strip as shown in Diagram above.

Terangkan apakah yang berlaku pada setiap jalur seperti yang ditunjukkan pada Rajah di atas.[10 marks/10 markah]

 (b) Explain the structure of the plasma membrane based on the fluid mosaic model proposed by S.J

Singer and Nicholson.Terangkan struktur membran plasma berdasarkan model mozek cecair yang dicadangkan oleh S.J Singer dan Nicholson.

[10 marks/10 markah] 

  

2. Three strips labelled W, X and Y are cut from a herbaceous plant. The strips are then immersed in sucrose solutions of different concentrations and in distilled water. Diagram below shows the condition of each strip after being immersed for 30 minutes in each solution.Tiga jalur berlabel W, X, dan Y dipotong dari satu pokok renek. Jalur itu kemudiannya direndam di dalam larutan sukrosa yang berlainan kepekatan dan di dalam air suling. Rajah di bawah menunjukkan keadaan setiap jalur selepas 30 minit direndam di dalam setiap larutan.

DIAGRAM / RAJAH 

(a) Explain what happens to each strip as shown in Diagram above.Terangkan apakah yang berlaku pada setiap jalur seperti yang ditunjukkan pada Rajah di atas.

[10 marks/10 markah] 

(b) Explain the structure of the plasma membrane based on the fluid mosaic model proposed by S.J Singer and Nicholson.Terangkan struktur membran plasma berdasarkan model mozek cecair yang dicadangkan oleh S.J Singer dan Nicholson.

[10 marks/10 markah] 

3. Diagram below shows the condition of plant cells in solutions of different concentrations, P, Q and R.Rajah di bawah menunjukkan keadaan sel tumbuhan didalam larutan P, Q dan R yang berbeza kepekatannya.

Diagram/Rajah 

(a) Identify solutions P, Q and R.Kenalpasti larutan P, Q dan R.

[3 marks/markah](b) Explain the condition of each cell in solution P, solution Q, solution R.

Jelaskan keadaan sel didalam larutan P, Q dan R secara berasingan.[9 marks/markah]

(c) i. Explain what happens when the plant cell from solution P is immersed in solution R?Jelaskan apakah yang akan berlaku kepada sel tumbuhan apabila direndamkan dalam larutan P dan kemudiannya dalam larutan R.

 [4 marks/markah]ii. Explain what happens when a red blood cell is immersed into solution P and then into solution R.

Jelaskan apakah yang akan berlaku kepada sel darah merah apabila direndamkan dalam larutan P dan kemudiannya dalam larutan R.

 [4 marks/markah]

4. Diagram below shows a red blood cell.Rajah di bawah menunjukkan sel darah merah.

Diagram/Rajah 

(a)

What is the function of red blood cells?Apakah fungsi sel darah merah?

[1 mark/1 markah](b)

Explain what happens when red blood cells are immersed in...Huraikan apa yang berlaku apabila sel darah merah direndam dalam...(i) a hypotonic solution,

larutan hipotonik,[3 marks/3 markah]

(ii)

an isotonic solution,larutan isotonik,

[3 marks/3 markah](iii)

a hypertonic solution.larutan hipertonik.

[3 marks/3 markah]

 (c)

Diagram belowshows a plant cell.Rajah di bawah menunjukkan sel tumbuhan.

Diagram /Rajah 

Explain what happens when plant cells are immersed in...Huraikan apa yang berlaku apabila sel tumbuhan direndam dalam...(i) a hypotonik solution,

larutan hipotonik,[4 marks/4 markah]

(ii)

an isotonik solution,larutan isotonik,

[2 marks/2 markah](iii)

a hypertonik solution.larutan hipertonik.

[3 marks/3 markah]

 (d)

Why do red blood cells and plant cells behave differently when they are immersed in a hypotonic solution?Mengapakah sel merah darah dan sel tumbuhan berkelakuan berbeza apabila direndam dalam larutan hipotonik?

[1 mark/1 markah]

 1.

(a) – Strip W is placed in 5% sucrose solution. The 5% sucrose solution is isotonic to the cell sap of the plant cell. [1 m]     – There is no net movement of water by osmosis. [1 m]     – So the strip maintains its shape. [1 m]     – Strip X is placed in distilled water. Distilled water is hypotonic to the cell sap of the plant cells.[1 m]     – The cuticle layer of strip X is impermeable to water. [1 m]     – Therefore water molecules move into the cell sap by osmosis. [1 m]     – So the plant cells become turgid and expand and strip X curves outwards. [1 m]     – Strip Y is placed in 30% sucrose solution. The 30% sucrose solution is hypertonic to the cell sap of the plant cells. [1 m]     – Water molecules diffuse out from the plant cells by osmosis into the surrounding hypertonic solution. [1 m]     – The cells become flaccid. [1 m]                                                          ____________          – Flaccid cells pull the epidermis and the strip curves inwards. [1 m] maximum: 10 m

(b)

   – The basic unit of the plasma membrane is the phospholipid molecule. [1 m]   – Phospholipid molecule consists of a polar phosphate molecule head which is hydrophilic (attracted to water) and two non-polar fatty acid tails which are hydrophobic (repelled from water). [1 m]   – Phospholipid units attract each other and they group together side by side to form a layer of phospholipids. [1 m]   – One layer of phospholipids forms over one another to produce the phospholipid bilayer.[1 m]   – Phospholipid bilayer – hydrophilic heads point outwards, facing water molecules on both sides. [1 m]   – Hydrophobic tails point inwards, away from water molecules. [1 m]   – Other molecules present in the plasma membrane   – cholesterol, proteins, glycolipids and glycoproteins [1 m]   – Cholesterol – fit in between the phospholipid molecules to stabilise the membrane structure and regulate the membrane fluidity. [1 m]   – Carrier proteins and channel proteins – assist and control the movement of water.                            – Glycolipids and glycoproteins help cells to recognize each other. [1 m]   maximum: 10 m 

2.

(a) – Strip W is placed in 5% sucrose solution. The 5% sucrose solution is isotonic to the cell sap of the plant cell. [1 m]     – There is no net movement of water by osmosis. [1 m]     – So the strip maintains its shape. [1 m]     – Strip X is placed in distilled water. Distilled water is hypotonic to the cell sap of the plant cells.[1 m]     – The cuticle layer of strip X is impermeable to water. [1 m]     – Therefore water molecules move into the cell sap by osmosis. [1 m]     – So the plant cells become turgid and expand and strip X curves outwards. [1 m]     – Strip Y is placed in 30% sucrose solution. The 30% sucrose solution is hypertonic to the cell sap of the plant cells. [1 m]     – Water molecules diffuse out from the plant cells by osmosis into the surrounding hypertonic solution. [1 m]     – The cells become flaccid. [1 m]     – Flaccid cells pull the epidermis and the strip curves inwards. [1 m]maximum: 10 m

(b)

                                                                                             [1 m]      – The basic unit of the plasma membrane is the phospholipid molecule. [1 m]      – Phospholipid molecule consists of a polar phosphate molecule head which is hydrophilic (attracted to water) and two non-polar fatty acid tails which are hydrophobic (repelled from water). [1 m]      – Phospholipid units attract each other and they group together side by side to form a layer of phospholipids. [1 m]      – One layer of phospholipids forms over one another to produce the phospholipid bilayer.[1 m]      – Phospholipid bilayer – hydrophilic heads point outwards, facing water molecules on both sides. [1 m]      – Hydrophobic tails point inwards, away from water molecules. [1 m]      – Other molecules present in the plasma membrane      – cholesterol, proteins, glycolipids and glycoproteins [1 m]      – Cholesterol – fit in between the phospholipid molecules to stabilise the membrane structure and regulate the membrane fluidity. [1 m]      – Carrier proteins and channel proteins – assist and control the movement of water.      – Glycolipids and glycoproteins help cells to recognize each other. [1 m]maximum: 10 m

3.

(a) P is a hypotonic solution, Q is an isotonic solution and R is a hypertonic solution. [3 m]     P ialah larutan hipotonik. Q ialah larutan istonik dan R ialah larutan hipertonik.(b) • When a plant cell is immersed in a hypotonic solution, water diffuses into the vacuole by osmosis. [1 m]         Apabila sel tumbuhan direndam di dalam larutan hipotonik, air diresap ke dalam vakuol melalui osmosis.     • The vacuole expands and swells. The vacuole and cytoplasm press against the plasma membrane which in turn presses against the cell wall. [2 m]        Vakuol mengembang dan membengkak. Vakuol dan sitoplasma menekan melawan  membran plasma kemudian menekan sel dinding.     • The plant cell becomes turgid. [1 m]        Sel tumbuhan menjadi segah.     • When a plant cell is immersed in an isotonic solution, water diffuses in and out of the cells at the same rate. [1 m]        Apabila sel tumbuhan direndam di dalam larutan isotonic, air akan diserap masuk dan keluar daripada sel pada kadar yang sama.     • Thus, there is no net movement of water across the plasma membrane. [1 m]        Oleh itu, tiada pergerakan tetap air merentasi membran plasma.     • The cell retains its normal shape. [1 m]        Sel mengekalkan bentuk yang sama.     • When a plant cell is immersed in a hypertonic solution, water diffuses out of the vacuole by osmosis. [1 m]        Apabila sel tumbuhan direndam di dalam larutan hipotonik, air akan diserap keluar daripada vakuol oleh osmosis     • The vacuole and the cytoplasm lose water to the surroundings and shrink. The plasma membrane pulls away from the cell wall. This is known as plasmolysis. [1 m]        Vakuol dan sitoplasma kehilangan air kepada persekitaran dan mengecut. Membran plasma ditolak keluar daripada dinding sel. Ini dikenali sebagai plamolisis.     • The plant cell becomes flaccid. [1 m]

        Sel tumbuhan menjadi falsid.(c) i. • When a turgid plant cell from solution P is immersed into solution R (hypertonic solution), the cell becomes flaccid. [1 m]           Apabila sel tumbuhan segah daripada larutan P direndam ke dalam larutan R(larutan hipertonik), sel menjadi flasid.        • The concentration of substances in the cytoplasm of the cell is lower compared to solution R. Therefore, water diffuses out of the cell by osmosis. [2 m]           Kepekatan zat di dalam sitoplasma sel rendah berbanding larutan R. Oleh itu, air diserap keluar daripada sel melalui osmosis.        • The vacuole shrinks and the plasma membrane pulls away from the cell wall. [1 m]           Vakuol mengecut dan membran plasma berjauhan daripada dinding sel.        • The cell is plasmolysed. [1 m]           Sel telah plasmolisis.     ii. • When a red blood cell is immersed in solution P, it becomes swollen because water diffuses into the cell by osmosis. [1 m]           Apabila sel darah merah direndam di dalam larutan P, ia menjadi membengkak kerana air terserap masuk ke dalam sel melalui osmosis.        • The solution outside the cell is less concentrated than the cytoplasm in the cell. The cell gains water. The cell swells up and eventually bursts. [1 m]           Larutan di luar sel  berkepekatan rendah berbanding sitoplasma di dalam sel. Sel memperoleh air. Sel mengembang dan pecah.        • The plasma membrane of the red blood cell is too thin and cannot withstand the osmotic pressure in the cell, causing it to rupture and the contents of the cell are released into the surroundings. [1 m]           Membran plasma bagi sel darah merah terlalu nipis dan tidak tahan kepada tekanan osmosi pada sel menyebabkan pecah dan kandungan di dalam sel akan terlepas ke persekitaran.        • The cell is haemolysed. [1 m]           Sel menjadi hemolisis.

4.

(a) To transport oxygen to the body cells [1 m](b) (i) • When red blood cells are immersed in a hypotonic solution, water moves into the cells by osmosis              because the concentration of water is higher in the solution than in the cells. [1 m]           • The cells swell up and may eventually burst if they are placed in an extremely hypotonic solution              such as distilled water. [1 m]           • This condition of the red blood cells is known as haemolysis. [1 m]     (ii) • When red blood cells are immersed in an isotonic solution, water moves into and out of the cells at               the same rate. [1 m]           • There is no net movement of water into or out of the cells. [1 m]           • There is no change in the shape of the cells. [1 m]    (iii) • When red blood cells are immersed in a hypertonic solution, water moves faster out of the cells than               into the cells because the concentration of water is higher in the cells than in the solution. [1 m]           • This net movement of water out of the cells makes the cells shrivel. [1 m]           • This condition of the red blood cells is known as crenation. [1 m](c) (i) • When plant cells are immersed in a hypotonic solution, water moves into the cells by osmosis because              the concentration of water is higher in the solution than in the cells. [1 m]           • The vacuoles of the cells expand, causing the cells to swell. [1 m]           • The vacuoles and cytoplasm of the cells press outwards against the plasma membranes which in turn              press against the cell walls. [1 m]           • The cells are said to be turgid but they do not burst because the rigid cell walls are strong enough to               withstand the pressure inside the cells. [1 m]     (ii) • When plant cells are immersed in an isotonic solution, water moves into and out of the cells at              the same rate. [1 m]

           • Since there is no net movement of water into or out of the cells, the shape of the cells does not              change. [1 m]    (iii) • When plant cells are immersed in a hypertonic solution, water moves out of the cells because the               concentration of water is higher in the cells than in the solution. [1 m]           • The vacuoles and cytoplasm of the cells shrink and the plasma membranes pull away from the              cell walls. [1 m]          • This phenomenon is known as plasmolysis and the cells become fl accid. [1 m](d) Red blood cells may burst when they are immersed in a hypotonic solution because their plasma        membranes are too thin to withstand the osmotic pressure in the cells, but plant cells do not burst because      their rigid cell walls are strong enough to resist the osmotic pressure in the cells. [1 m]