TRANSPORT IN CELLS

Question 1

What is diffusion?

Answer 1

The net movement of particles from an area of high concentration to a low concentration through a partially permeable membrane

Question 2

What are the main factors affecting diffusion?

Answer 2

•Concentration gradient- larger gradient, faster diffusion
•Temperature- high temperature, faster diffusion
•Surface area- larger surface area, faster diffusion

Question 3

What are examples of diffusion in the body?

Answer 3

•Oxygen and Carbon Dioxide in the alveoli
•Urea from cells into the blood to be urinated

Question 4

How can organisms be adapted for diffusion?

Answer 4

•Large SA:Volume ration to maximise the rate of diffusion of molecules

Question 5

How is Surface Area to volume calculated?

Answer 5

SA= Number of sides x (side length x side width)
Volume= length x width x depth
Ratio= SA: Volume

Question 6

What four factors increase the effectiveness of a gas exchange surface?

Answer 6

•Large surface area
• Thin membrane
•rich blood supply
•Ventilation

Question 7

What is osmosis?

Answer 7

The movement of water from a high concentration to a low concentration through a partially permeable membrane

Question 8

What is meant when a solution is isotonic to the cell?

Answer 8

The concentrations of the external and internal solutions are the same

Question 9

What is meant when a solution is hypertonic to a cell?

Answer 9

The solution has a higher external concentration than internal

Question 10

What is meant when a solution is hypotonic to a cell?

Answer 10

The internal concentration is greater than the external concentration of the solution

Question 11

What happens when an animal cell is placed in a hypotonic solution?

Answer 11

Water moves into the cell and it bursts

Question 12

What happens when an animal cell is placed in a hypertonic solution?

Answer 12

Water moves out of the cell and it shrivels

Question 13

How do plant leaves and stems stay rigid?

Answer 13

•Turgor Pressure
•Water moves in by osmosis and the vacuole wells meaning the cytoplasm presses against the cell wall

Question 14

What is meant by plasmolysed?

Answer 14

When a plant cell wall has had the cell membrane detached from it after being placed in a hypertonic solution

Question 15

What is active transport?

Answer 15

The movement of particles from a low to high concentration through a partially permeable membrane against the concentration gradient

Question 16

How do plant root hair cells use active transport?

Answer 16

•Mineral ions taken up from soil
•Ions such as magnesium and nitrates are essential for a healthy plant growth

Question 17

How is active transport used in the human body?

Answer 17

•Active transport is used to transport glucose from a lower concentration in the gut to a higher concentration in the blood
•EG Small intestine into the blood so glucose can be used for respiration after transported to cells and tissues