Question 1: Define active transport in the context of cellular processes.

Answer: Active transport is the process by which cells move molecules or ions against their concentration gradient using energy, often from ATP.

Question 2: Describe the main difference between passive transport and active transport.

Answer: Passive transport does not require energy and moves substances along their concentration gradient, whereas active transport requires energy to move substances against their concentration gradient.

Question 3: Explain how ATP is utilised in active transport mechanisms.

Answer: ATP provides the energy needed to change the shape of carrier proteins in the cell membrane, allowing ions or molecules to be transported against their concentration gradient.

Question 1: If a cell uses 1.2 × 10⁻⁹ joules of energy to transport 1000 ions across the membrane, what is the energy cost per ion in joules?

Answer: 1.2 × 10⁻¹² joules

Question 2: Calculate the power in watts used if the energy transfer occurs over 10 seconds when transporting 500 molecules, given that each molecule requires 2 × 10⁻¹⁸ joules.

Answer: 1 × 10⁻¹⁴ watts

Question 1: Describe an experimental setup to investigate the effect of temperature on active transport in plant root cells.

Answer: Use a sample of plant roots in solutions at different temperatures, measure the uptake of a dye or ion over time, and compare the rates of transport at each temperature, ensuring all other variables are controlled.

Question 2: Identify two safety precautions that should be observed during the experiment.

Answer: Wear gloves and safety goggles to protect against chemical spills and ensure proper handling of equipment and solutions.

Question 1: A scientist measures the rate of sodium ion uptake in cells at different energy levels. When ATP supply is low, the rate is 50 units; when ATP supply is high, the rate increases to 200 units. Explain how ATP influences active transport based on this data.

Answer: The data indicates that higher ATP availability increases active transport rates, as ATP provides the energy necessary for carrier proteins to move ions against their concentration gradient.

Question 1: Describe the role of carrier proteins in active transport. (6 marks)

Answer: Carrier proteins are specialised proteins embedded in the cell membrane that bind to specific ions or molecules. They change shape using energy from ATP to transport substances against their concentration gradient, enabling cells to maintain necessary internal conditions such as ion balances and nutrient uptake.

Question 1: Explain how active transport is essential in kidney function, particularly in the reabsorption of glucose and ions.

Answer: Active transport allows kidney cells to reabsorb glucose and ions from the filtrate back into the blood, maintaining proper nutrient and electrolyte balance, which is vital for homeostasis.

Question 2: Discuss how advances in understanding active transport can lead to the development of new medical treatments.

Answer: Understanding active transport mechanisms can help develop drugs that target transporter proteins, improving treatments for conditions like cystic fibrosis, hypertension, and certain neurological disorders by enhancing or inhibiting specific transport processes.