SPM Biology 2014

Question

6 . Diagram 6.1 shows a plant in two different conditions M and N.

Rajah 6.1 menunjukkan suatu tumbuhan dalam dua keadaan yang berbeza, M dan N.Cher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution

(a)(i) Based on Diagram 6.1, explain what happens to the plant in condition M.
Berdasarkan Rajah 6.1, terangkan apa yang berlaku kepada tumbuhan itu dalam keadaan M.

(ii) Explain one way which enables the plant in condition M to be as in condition N.
Terangkan satu kaedah yang membolehkan tumbuhan dalam keadaan M menjadi seperti di dalam keadaan N.

Cher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution

(b) A student carries out an experiment to investigate the percentage of red blood cell undergoes haemolysis when immersed in different concentration of sodium chloride solution. The following graph shows the results of the experiment. Based on the graph, explain what happens to the red blood cells at R and S.

Seorang murid menjalankan eksperimen untuk menyiasat peartusan sel darah merah yang mengalami hemolisis apabila direndam ke dalam larutan natrium klorida berlainan kepekatan. Graf berikut menunjukkan keputusan eksperimen itu. Berdasarkan kepala graf, terangkan apakah yang berlaku kepada sel darah merah pada R dan S.Cher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution

 

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Answer ( 1 )

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    2021-02-28T17:48:37+08:00

    6.a)i) -The soil water is hypertonic to the cytoplasm of the plant cell.

    -Thus water diffuses out of the plant cell via osmosis.

    -This causes the vacuole to shrink and the cell membrane to pull away from the cell wall.

    -The plant cell has plasmolysed and becomes flaccid. The plant loses its turgidity and starts to wilt.

     

    ii)-The plant has to be watered.

    -By watering the plant and the surrounding soil, the soil water becomes less concentrated and hypotonic to the cytoplasm of the plant cell.

    -Thus water will diffuse into the plant cell via osmosis.

    -Water diffuses into the vacuole, this causes the vacuole to enlarge and swell up. The vacuole and cytoplasm expand outwards, pressing against the plasma membrane. Then the plasma membrane presses against the cell wall.

    -There is now turgor pressure within the cell.

    -The plant becomes turgid again, the process of deplasmolysis has occurred.

     

    b)-In R, the sodium chloride solution is less concentrated. The solution is hypotonic to the cytoplasm of the red blood cell.

    -Thus via osmosis, water diffuses into the red blood cell.

    -This causes the cell to swell and eventually as more water keeps entering the cell, the cell will eventually expand until it bursts.

    -Since the cell membrane of red blood cells are delicate and thin, they are not able to withstand the osmotic pressure created within the cell, thus the cell bursts.

    -Cell contents are released to the solution (haemolysis has occurred).

    -Since the solution is very hypotonic all the cells have undergone haemolysis (100%).

     

    -In S the sodium chloride solution is highly concentrated. The solution is hypertonic to the cytoplasm of the red blood cell.

    -Thus via osmosis, water will diffuse out of the red blood cell.

    -The cell will start to shrink and its cell membrane crinkles.

    -The cell has undergone crenation.

    -Since water doesn’t enter the cell, the cell doesn’t undergo haemolysis so percentage is near 0%.

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