Formative Practice 3.2 (Form 4 Biology Textbook Exercise and Answer)

Question 1:
Give some examples of substances that are able to pass through the phospholipid bilayer.

Oxygen, carbon dioxide, water.

Question 2:
Describe how sodium ions are transported out of the cell.

Three sodium ions bind to the carrier protein.
The ATP molecule is broken down to ADP and P.
The phosphate group binds to the carrier protein.
The phosphate bond provides energy and changes the shape of the carrier protein, which then transports the sodium ions out though the carrier protein.

Question 3:
A scientist conducts an experiment by soaking the roots of a plant in a solution which contains mineral salts at different levels of oxygen concentrations. Explain why the mineral salts concentration in the roots increased when the oxygen concentration in the solution increases by 10%.

The uptake of mineral salt ions by plant roots is through active transportat and involves the usage of energy.
More energy is generated when root cells carry out more cellular respiration using oxygen.
As such, the concentration of mineral salt ions in the root increases when the concentration of oxygen in the solute increases by 10%.

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