Let's break down the problem step by step, using the given concentrations to answer each part of the question thoroughly.
(a) Complete the sentences.
Based on the concentrations given in the table:
- Chloride ions have a higher concentration outside the cell (116 units) than inside the cell (4 units).
- Potassium ions have a higher concentration inside the cell (120 units) than outside the cell (4 units).
Given the options (active transport, diffusion, osmosis):
- Chloride ions move into the cell by diffusion because they move from a higher concentration (outside) to a lower concentration (inside), and this movement is a passive process not requiring energy.
- Potassium ions move into the cell by active transport because they move from a lower concentration (outside) to a higher concentration (inside), which requires energy input and is not a passive process.
So, the completed sentences are:
- Chloride ions move into the cell by diffusion.
- Potassium ions move into the cell by active transport.
(b) Why do sodium ions move into the cell?
The concentration of sodium ions is higher outside the cell (145 units) compared to inside the cell (12 units).
Sodium ions move into the cell because their concentration outside the cell is higher than inside the cell, and they move down their concentration gradient. This means sodium ions naturally move from a region of higher concentration (outside) to a region of lower concentration (inside) by diffusion.
(c) Calculate how many times greater the potassium ion concentration is inside the cell compared with outside the cell.
The concentration of potassium ions inside the cell is 120 units, and the concentration outside is 4 units.
To find how many times greater the concentration inside the cell is compared to outside, we can use the ratio of inside concentration to outside concentration:
[tex]\[ \text{Number of times greater} = \frac{\text{Concentration inside the cell}}{\text{Concentration outside the cell}} = \frac{120}{4} = 30 \][/tex]
So, the potassium ion concentration inside the cell is 30 times greater than outside the cell.
In summary:
(a) Chloride ions move into the cell by diffusion. Potassium ions move into the cell by active transport.
(b) Sodium ions move into the cell because their concentration outside the cell is higher than inside the cell, and they move down their concentration gradient.
(c) The potassium ion concentration inside the cell is 30 times greater than outside the cell.
