Transport in Cells

Question 1

What is diffusion?

Answer 1

Diffusion is the net movement of particles from one area of high concentration to an area of low concentration down a concentration gradient. It is a passive process so no energy is needed and occurs until equilibrium.

Question 2

What can pass through the cell membrane by diffusion and what can’t?

Answer 2

CAN:oxygen, glucose, amino acids, water
CANT:starch, proteins

Question 3

What is a dilute solution?

Answer 3

When a solution has a HIGH water concentration

Question 4

What is a concentrated solution?

Answer 4

When a solution has a LOW water concentration

Question 5

What is osmosis?

Answer 5

The movement of water particles from a dilute region to a concentrated region down a concentration gradient across a partially permeable membrane

Question 6

What is a hypotonic solution?

Answer 6

When there is more water OUTSIDE the cell, water will move IN via osmosis.

Question 7

What is a hypertonic solution?

Answer 7

Less water OUTSIDE than inside cell so water LEAVES cell via osmosis

Question 8

What is an isotonic solution?

Answer 8

When there are equal amounts of water inside and outside solution so there is no NET MOVEMENT.

Question 9

What happens to an ANIMAL cell in a HYPERTONIC solution?

Answer 9

Water leaves cell so the red blood cell shrivels and becomes CRENATED.

Question 10

What happens to an ANIMAL cell in a HYPOTONIC solution?

Answer 10

Water moves IN but the red blood cell bursts as there is TOO MUCH water. This is called LYSIS.

Question 11

What happens to a PLANT cell in a HYPERTONIC solution?

Answer 11

Water leaves VACUOLE via osmosis but some water remains. Shape of cell is less rigid but as more water leaves vacuole becomes SMALLER and CYTOPLASM and CELL MEMBRANE fade away. The cell has PLASMOLYSED or become FLACCID

Question 12

What happens to a plant cell in a hypotonic solution?

Answer 12

Water moves IN so cell gains lots of water and expands. Cell will not BURST as it has a RIGID CELLULOSE WALL and animal cell doesn’t. The cell is TURGID.

Question 13

What can affect the rate of DIFFUSION?

Answer 13

Difference in concentrations
The temperature
The surface area

Question 14

What can increase the effectiveness of an exchange surface?

Answer 14

Having a large surface area
A membrane that is thin
having an efficient blood supply
being ventilated

Question 15

What is active transport?

Answer 15

Active transport moves substances from a more dilute solution to a more concentrated solution( AGAINST a concentration gradient). This requires energy in the form of ATP from respiration.

Question 16

What does active transport help with?

Answer 16

Allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soul. It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar is used for CELL RESPIRATION.

Question 17

How are lungs an effective EXCHANGE SURFACE?

Answer 17

Lungs have alveoli which have a LARGE SA and have very thin walls, capillaries surround alveoli ensuring GOOD BLOOD SUPPLY and lungs are WELL VENTILATED.

Question 18

Why is the small intestine an effective EXCHANGE SURFACE?

Answer 18

Projections called VILLI and MICROVILLI increase surface area for absorption.Blood capillaries inside maintain good blood flow and transport molecules away to maintain a concentration gradient.Villi also have a THIN PERMEABLE MEMBRANE for a shorter diffusion path.

Question 19

Why are gills an effective exchange surface?

Answer 19

Feather projections called filaments to increase SA for gas exchange. Water pumped over gills for a steep concentration gradient and for ventilation. Thin walls to provide short diffusion path and capillaries ensuring good blood supply.

Question 20

How are leaves an effective exchange surface?

Answer 20

FLATTENED SHAPE to increase surface area for gas exchange.Small holes that allow for movement of gases to keep ventilated. Very thin to ensure short diffusion path.