4.1.3.3 Active Transport

Question 1

Active transport:

Answer 1

• The net movement of particles from an area of low concentration to an area of high concentration against a concentration gradient across a partially permeable membrane
• This is an active process so therefore requires energy from respiration therefore from mitochondria as they release energy throughout aerobic respiration

Question 2

Why is active transport needed?

Answer 2

Transport or carrier proteins are needed to get the molecules into the cells and these use energy

Question 3

What are some cell adaptations for active transport?

Answer 3

• Cells that do active transport contain large numbers of mitochondria. This means that they carry out lots of aerobic respiration to release energy (in the form of ATP (adenosine and triphosphate) to carry out active transport
• Lots of ribosomes as they are the site of protein synthesis and carrier proteins are needed to get these molecules into cells which uses energy.

Question 4

Biological examples of active transport: Marine fish

Answer 4

Have cells in their gills that can pump salt back into the salty sea water

Question 5

Biological examples of active transport: Thyroid gland

Answer 5

Cells in the thyroid gland take in iodine to use in the production of hormones

Question 6

Biological examples of active transport: kidney

Answer 6

Cells in the kidney re-absorb sodium ions from urine

Question 7

Biological examples of active transport: crocodiles

Answer 7

Have salt glands in their tongues that remove excess salt from their bodies

Question 8

Biological examples of active transport: villi

Answer 8

Villi in the small intestine absorb glucose and amino acids into the blood

Question 9

Biological examples of active transport: Active transport in the gut

Answer 9

• When there’s a higher concentration of glucose and amino acids in the gut they diffuse naturally into the blood
• But sometimes there’s a lower concentration of nutrients in the gut than there is in the blood
• Active transport allows nutrients to be taken into the blood, against the concentration gradient
• This is essential to stop us starving
• It means that glucose can be transported in the bloodstream when its concentration in the blood is already higher than in the gut

Question 10

Biological examples of active transport: Active transport of sugar molecules in the gut:

Answer 10

• Active transports allows sugar molecules to be transported from lower concentrations in the gut into the blood which has a higher sugar concentration
• The glucose can be transported into cells, where it’s used for respiration

Question 11

Biological examples of active transport: Root hair cells

Answer 11

• Plants need mineral elements from the soil for healthy growth
• It allows mineral ions to be absorbed into plant root hairs from a very dilute solution in the soil
• Minerals enter a plant through its roots
• When plants absorb nitrate ions through the root hairs from the soil water
• The concentration of nitrate ions in soil water is usually less than the concentration of nitrate ions inside the root hair cell
• Nitrate ions naturally diffuse down their concentration gradient, out of the cell and into the soil, but plants transport the nitrates into their soil using active transport which is the movement of particles from a low contraction to a high concentration against a concentration gradient across a partially permeable membrane

Question 12

Describe the ion concentration the root hair cell in relation to the soil (4). Predict which direction the ions will move (5/6). Suggest an explanation for this movement (7/8).

Answer 12

• There is a higher concentration in the root hair cell than in the soil
• The ions move from the soil into the root
• Plants need mineral ions to survive e.g. make chlorophyll
• They use energy to move against the concentration gradient by active transport (via carrier proteins)

Question 13

What happens in just diffusion?

Answer 13

How O2 leaves a leaf

Question 14

What happens in just osmosis?

Answer 14

• Involves water only
• How water keeps plant cells turgid

Question 15

What happens in just active transport?

Answer 15

• Requires energy
• Against a concentration gradient
• How minerals get into root hair cells

Question 16

What happens in diffusion and active transport?

Answer 16

Involves transport of solutes

Question 17

What happens in diffusion and osmosis?

Answer 17

• Is a passive process
• High to low concentration so down a concentration gradient

Question 18

What happens in osmosis and active transport?

Answer 18

Needs a partially permeable membrane

Question 19

What happens in diffusion, osmosis and active transport?

Answer 19

• Movement of particles
• Occurs in nature

Question 20

What are transport and carrier proteins needs for?

Answer 20

Transport or carrier proteins are needed to get the molecules into the cells and these use energy

Question 21

What does active transport allow in plants?

Answer 21

Allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil

Question 22

What does active transport allow in humans?

Answer 22

• Allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration
• Sugar molecules are used for cell respiration

Question 23

Diagram showing active transport in root hair cells:

Answer 23