3.2 Active Transport (Cambridge (CIE) O Level Biology): Flashcards
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Define active transport.
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Cards in this collection (20)
Define active transport.
The movement of particles across a cell membrane from a region of lower concentration to a region of higher concentration, using energy from respiration.
Give two examples of active transport in living organisms.
Uptake of glucose by epithelial cells in the villi of the small intestine (and by kidney tubules)
Uptake of ions from soil water by root hair cells in plants
Active transport moves particles the concentration gradient.
Active transport moves particles against the concentration gradient.
Why do root hair cells use active transport?
To absorb mineral ions from the soil, where the ions are at a lower concentration than inside the cell.
Where does the energy for active transport come from?
From respiration — energy is needed because particles are moved against the concentration gradient.
Where in the digestive system is glucose taken up by active transport?
By the epithelial cells of the villi in the small intestine.
True or False?
Active transport moves particles down the concentration gradient.
False.
Active transport moves particles against the gradient (from low to high concentration), which is why it needs energy.
Root hair cells absorb mineral from the soil by active transport.
Root hair cells absorb mineral ions from the soil by active transport.
How does active transport differ from diffusion?
Active transport moves particles against the concentration gradient and needs energy from respiration; diffusion is passive and moves particles down the gradient.
Why can't the small intestine rely only on diffusion to absorb all glucose?
When the glucose concentration in the gut becomes lower than in the blood, active transport is used to absorb the remaining glucose against the gradient.
Unlike diffusion, active transport requires from respiration.
Unlike diffusion, active transport requires energy from respiration.
True or False?
Glucose is reabsorbed in the kidney tubules by active transport.
True.
The kidney tubules (in the nephron) use active transport to reabsorb glucose.
Why does active transport require energy?
Because particles are moved against their concentration gradient — the opposite direction to diffusion.
Glucose is absorbed by active transport in the of the small intestine.
Glucose is absorbed by active transport in the villi of the small intestine.
Define a concentration gradient.
The difference in concentration of a substance between two regions; active transport moves substances against it.
Why is active transport described as a vital process?
It lets cells take up essential molecules and ions (such as glucose and minerals) even when they are at a lower external concentration.
True or False?
A cell carrying out a lot of active transport is likely to contain many mitochondria.
True.
Mitochondria release the energy from respiration needed to power active transport.
Active transport uses energy released during .
Active transport uses energy released during respiration.
In which direction are particles moved during active transport?
From a region of lower concentration to a region of higher concentration.
What would happen to ion uptake by root hair cells if the plant could not respire?
Ion uptake by active transport would stop, because there would be no energy from respiration to move ions against the gradient.
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