Question 1: Define active transport in the context of cell biology.

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

Question 2: Explain why active transport requires energy and how this energy is supplied.

Answer: Active transport requires energy because it moves substances against their concentration gradient; this energy is supplied by ATP hydrolysis.

Question 3: Describe the role of protein carriers in active transport.

Answer: Protein carriers span the cell membrane and change shape to transport specific molecules or ions against their concentration gradient using energy.

Question 1: A cell transports 2.5 x 10^6 ions per second using active transport. If each ion requires 1 ATP molecule to be transported, calculate the total number of ATP molecules consumed in one minute.

Answer: Total ATP = (Number of ions per second) x (Seconds in a minute) = 2.5 x 10^6 x 60 = 1.5 x 10^8 molecules of ATP.

Question 2: If the energy cost per molecule of transported ion is 30 kJ/mol, estimate the total energy expenditure in kilojoules for transporting 1 x 10^8 ions.

Answer: Energy = (Number of moles) x (Energy per mole) = (1 x 10^8 ions / 6.022 x 10^23 ions/mol) x 30 kJ/mol ≈ 4.98 x 10^-16 kJ.

Question 1: Describe a simple experiment to investigate the effect of temperature on active transport in plant root hairs.

Answer: The experiment involves exposing identical plant root hair samples to different temperatures (e.g., 10°C, 20°C, 30°C), then measuring the rate of ion uptake using a suitable indicator or tracer. Variables include temperature (independent), rate of ion uptake (dependent), and type of plant (controlled). Safety precautions include handling equipment carefully and maintaining appropriate temperature ranges.

Question 2: Identify two variables that should be controlled in an experiment measuring active transport in animal cells.

Answer: The concentration of ions outside the cell and the duration of the experiment.

Question 1: A study measures the rate of sodium ion transport in kidney cells at different ATP concentrations. The data show that increasing ATP concentration from 1 mM to 5 mM increases the transport rate from 50 units to 250 units, then plateaus. Explain what this suggests about the active transport mechanism.

Answer: It suggests that active transport is facilitated by ATP-dependent carrier proteins, and that at higher ATP concentrations, the transport rate reaches a maximum (saturation point) where all carriers are occupied.

Question 1: Explain how active transport is essential in the absorption of nutrients in the small intestine.

Answer: Active transport allows the absorption of nutrients like glucose and amino acids against their concentration gradients, ensuring efficient uptake into blood capillaries.

Question 2: Describe how understanding active transport can contribute to the development of new medications or treatments.

Answer: Knowledge of active transport mechanisms enables the development of drugs that target specific carrier proteins, potentially improving treatments for conditions like drug resistance or nutrient absorption deficiencies.