Scientists measured the concentration of sodium ions and potassium ions in the red blood cells and in the blood plasma of a group of people. The results are shown in Table 1.1. Table 1.1 mean concentration of sodium ions / $\text{mmol dm}^{-3}$ mean concentration of potassium ions / $\text{mmol dm}^{-3}$ --- --- --- red blood cells 10 100 blood plasma 100 4 (i) Use the information in Table 1.1 to identify and describe the process by which potassium ions enter red blood cells…

Biology 9700/21 — October/November 2023

Cambridge AS Level · AS Level Structured Questions · worked solutions for every part, with the mark scheme

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Topics Biological Molecules · Cell Membranes and Transport · Nucleic Acids and Protein Synthesis · Immunity · Cell Structure · Transport in Plants · +5 more

Q1Free sample

Scientists measured the concentration of sodium ions and potassium ions in the red blood cells and in the blood plasma of a group of people. The results are shown in Table 1.1.

Table 1.1

	mean concentration of sodium ions / $\text{mmol dm}^{-3}$	mean concentration of potassium ions / $\text{mmol dm}^{-3}$
red blood cells	10	100
blood plasma	100	4

(a)

(i)

Use the information in Table 1.1 to identify and describe the process by which potassium ions enter red blood cells from the blood plasma.

(ii)

Sodium ions and oxygen molecules enter red blood cells.

State one similarity and one difference between the processes used by sodium ions and oxygen molecules to enter red blood cells.

similarity ______
difference ______

(iii)

Chloride ions move across the membrane of human red blood cells in a process called the chloride shift.

Explain why the chloride shift is important in the transport of carbon dioxide from respiring tissues.

(b)

Scientists studied the uptake of a substance, F, by human red blood cells.

The red blood cells were immersed in a solution of substance F for 30 minutes. After this time the scientists recorded two observations:

the cell surface membrane of the red blood cells showed infoldings (invaginations)
an increase in the number of vesicles in the cytoplasm.

Identify the process by which substance F entered the red blood cells.

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